Clinical course of hospitalizations with Influenza, SARS-CoV-2 and respiratory syncytial virus (RSV) infections in the season 2024/2025 in a large German primary care centre and comparison with the previous two years

Clinical course of hospitalizations with Influenza, SARS-CoV-2 and respiratory syncytial virus (RSV) infections in the season 2024/2025 in a large German primary care centre and comparison with the previous two years | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Clinical course of hospitalizations with Influenza, SARS-CoV-2 and respiratory syncytial virus (RSV) infections in the season 2024/2025 in a large German primary care centre and comparison with the previous two years Benno Trautwein, Rudolf A. Jörres, Sebastian Engelhardt, Peter Alter, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8402845/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 12 You are reading this latest preprint version Abstract Background Respiratory viruses including influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 continue to cause morbidity and mortality, particularly in older adults and young children. We aimed to assess their clinical impact and outcomes in the 2024/25 season in comparison with the past two seasons, using data from the same primary care hospital in Southern Germany. Methods Retrospective analysis of patients hospitalized with PCR-confirmed SARS-CoV-2, Influenza A/B, or RSV infection between August 2024 and April 2025 in the internal, neurological and paediatric departments. Clinical characteristics including comorbidities, symptoms, laboratory parameters and outcomes were analyzed, with focus on the need/type of respiratory support, admission to intensive care, and death. Results Of 723 patients included, 714 had mono infections with SARS-CoV-2 (40.0%), influenza A (35.7%) or B (8.2%), or RSV (14.8%), with high frequency in young children and older adults. Among patients ≥ 18 years of age (n = 514, 48.3% SARS-CoV-2, 41.3% Influenza A, 3.1% Influenza B, 6.6% RSV), admission to the intensive care unit (ICU) was required in 42 patients (8.1% SARS-CoV-2, 8.5% Influenza A, 6.3% Influenza B, 8.8% RSV), and 51 patients died (13.3% of SARS-CoV-2, 6.1% Influenza A, 6.3% Influenza B, 11.8% RSV). The highest demand for oxygen therapy and mechanical invasive ventilation occurred with RSV. Among patients < 18 years of age (n = 209, 19.6% SARS-CoV-2, 22.0% Influenza A, 21.1% Influenza B, 34.9% RSV), 5 were admitted to the ICU (4.8% of SARS-CoV-2, 0.0% Influenza A, 4.5% Influenza B, 1.5% RSV), and none died. Compared to the two preceding seasons, there were variations but no statistically significant changes in prevalence and outcome. Mortality in adults tended to increase for SARS-CoV-2 and decrease for RSV. Moreover, Influenza A and RSV activity shifted toward later months, and Influenza B emerged prominently only in 2024/25. Conclusions During the 2024/25 season, the distribution of viral respiratory tract infections showed no major differences compared to the two previous seasons; however, Influenza B re-emerged in substantial numbers. Overall, infections with SARS-CoV-2 were still most frequent, and in adult patients mortality tended to be twice as high as in patients with influenza. Figures Figure 1 Figure 2 Introduction Seasonal respiratory viruses such as influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 continue to pose a significant public health burden, particularly in older adults and small children and predominately during the winter months, contributing to the number of hospitalizations and mortality [ 1 ]. Subsequent to the COVID-19 pandemic, the epidemiological characteristics of these infections have changed with regard to their prevalence, outcomes and risk profiles [ 1 ], [ 2 ]. In two previous studies [ 3 ], [ 4 ] we utilized data from a large German primary care hospital, to assess the characteristics and outcomes of patients hospitalized with influenza A, SARS-CoV-2, or RSV during the 2022/23 and 2023/24 seasons, with the aim to enable longitudinal comparisons through consistent methodology and data collection. The first study addressed the dynamics after the end of the dominance of SARS-CoV-2 and the re-emergence of “classical” respiratory viruses such as influenza A and RSV [ 4 ]. The second study extended this investigation to the following season, seeking to identify whether and in which way the situation had changed within one year [ 3 ]. Both analyses provided valuable data on the prevalence and relevance of respiratory viral infections after the COVID-19 pandemic. The present study continues this line of research by examining the 2024/25 season, based on the fact that trajectories of respiratory virus activity remain unpredictable and either new trends may have emerged or previously observed patterns may have become stable. To further ensure comparability, patient characteristics and clinical outcomes were assessed using the same methodology as in the previous two seasons. However, the observation period was extended to the time from August 2024 to April 2025, corresponding to the surveillance window used by the German Robert Koch-Institute (RKI) for 2024/25. According to its reports, influenza and RSV activity persisted beyond February, whereby the influenza wave was terminated only in week 14/2025 and the RSV wave in week 15/2025 [ 5 ], [ 6 ]. To facilitate comparisons with previous seasons, we performed sub-analyses with shorter time windows as used in our previous studies [ 3 ], [ 4 ]. Moreover, the RSV immunization in infants and vaccination in adults as recently established in Germany introduced a new factor that may have influenced the clinical outcome [ 7 ]. Based on these considerations, the present study assessed the clinical characteristics and outcomes of patients of all ages hospitalized due to acute respiratory viral infections in a large primary care hospital in southern Germany in 2024/25 and compared the results with those of the previous two seasons. Materials and methods Study population This retrospective analysis used data of hospitalized patients of all ages collected at the RoMed Hospital Rosenheim, Bavaria, Germany, between August 1st, 2024, and April 30th, 2025. This primary-care hospital covers a population of approximately 320.000 inhabitants. If there was any clinical suspicion on the presence of a viral infection, a multiplex PCR test for SARS-CoV-2, Influenza A/B, and RSV was performed. Consequently, patients with confirmed PCR-positive results for SARS-CoV-2, Influenza A/B, RSV, or co-infections involving these viruses were included. If patients were re-admitted within 4 weeks for the same infection, only the first admission was chosen. This resulted in 825 patients. In the next step, we aimed to exclude patients in whom the likelihood that the infection was incidental and not causally related to hospitalization was high. Thus, based on previous experience [ 8 ] and in agreement with our previous analyses [ 3 ], [ 4 ], specialties such as gynaecology, surgery, and urology were excluded (n = 102), and we selected only patients admitted to the departments of internal medicine, neurology and paediatrics. This resulted in a final study population of 723 patients. Approval for this retrospective study was obtained from the Ethics Committee of the University Hospital of Regensburg (Number 25-4131-104) which served as an Institutional Review Board. Moreover, the study was in full accordance with the Declaration of Helsinki. According to the Institutional Review Board, there was no need for patients’ consent to participate in this retrospective analysis of anonymized data. Clinical trial number: not applicable . Assessments The presence and type of infection were determined by PCR (polymerase chain reaction) testing, conducted either upon hospital admission or during the inpatient stay. For the 2024/25 season, the PCR assays employed were the STANDARD™ M10 SARS-CoV-2 and STANDARD™ M10 FLU/RSV/SARS-CoV-2 kits (SD BIOSENSOR, INC., Suwon, Republic of Korea) that covered all infections addressed in the present study. In case of invalid or inconclusive results, confirmation was achieved through repeated testing, either using the same multiplex assay or its virus-specific version. Clinical and laboratory data were extracted using the KIS Medico software package (Version 29, CGM Clinical Europe GmbH, Koblenz, Germany), and additional information was taken from the written clinical reports of each patient. The collected data included age, sex, body mass index (BMI), and a range of comorbidities comprising hypertension, coronary artery disease, diabetes mellitus type 2, COPD, asthma and other common diseases from internal medicine, similar as in the previous studies [ 3 ], [ 4 ]. Symptoms upon admission encompassed cough, dyspnea, fatigue, fever, diarrhea, and nausea. Vital signs included systolic and diastolic blood pressure, respiratory rate, heart rate, body temperature, and peripheral oxygen saturation (SpO 2 ). Laboratory analyses on admission were based on peripheral venous blood samples and comprised estimated glomerular filtration rate (eGFR) computed from creatinine, C-reactive protein (CRP), and D-dimers. Blood gas parameters included pH, as well as arterial partial pressures of oxygen (pO 2 ) and carbon dioxide (pCO 2 ). All of these variables referred to the patients’ state upon admission. Furthermore, the application of antiviral treatment and the presence of RSV immunization in infants were assessed. Outcomes The primary outcomes selected for the comparison between infection types were ICU (intensive care unit) admission and in-hospital mortality. Secondary outcomes were respiratory support including the administration of invasive mechanical ventilation, non-invasive ventilation (NIV), as well as high-flow and low-flow oxygen therapy. High-flow oxygen therapy (HFNC, high flow nasal cannula) was delivered via cannula or Venturi mask with flow rates ranging from 30 to 60 L/min, whereas low-flow oxygen therapy was provided at flow rates between 2 and 6 L/min using either a simple face mask or nasal cannula. In addition, length of hospital and intensive care unit stay, and antiviral treatment were assessed. Data analysis Descriptive statistics are presented as counts and percentages, or as median values with quartiles, depending on the data type. To compare infection categories, either the (exact) Fisher-Freeman-Halton test or the Kruskal-Wallis analysis of variance was applied, as appropriate. If the Kruskal-Wallis test indicated significant differences, post hoc pairwise comparisons were conducted using the Mann-Whitney U-test with Bonferroni corrections to adjust for multiple testing. The Fisher-Freeman-Halton test was also used to compare data between the three seasons. Correspondingly, Fisher’s exact test for 2x2 tables was used to reveal potential effects of RSV immunization in infants. Logistic regression analysis was employed to determine whether the associations of symptoms or comorbidities with infection type were influenced by patients’ age and sex. In addition, logistic regression analyses were performed to identify and quantify potential associations between primary outcomes and patient characteristics and infection types. A two-sided p-value < 0.05 was considered statistically significant. All statistical analyses were conducted using the SPSS software (version 31; IBM Corporation, Armonk, NY, USA). Results Anthropometric data and distribution of infections Out of 825 patients across all departments, 723 patients from the departments of internal medicine, paediatrics or neurology remained for analyses (337 women (46.6%), 386 men (53.4%)). Median (quartiles) age and BMI were 69.0 (6.0; 81.0) years and 25.3 (22.5, 29.7) kg/m², respectively (Table 1 ). Table 1 Baseline characteristics of each type of viral infection Number * N (< 18 years)** n (≥ 18 years)** Sex (m/f) Age (years) BMI (kg/m 2 ) a Total 723 209 (28.9%) 514 (71.1%) 386/337 (53.4%/46.6%) 69.0 (6.0; 81.0) 25.3 (22.5; 29.7) SARS-CoV-2 289 (40.0%) 41 (19.6%) 248 (48.3%) 157/132 (54.3%/45.7%) 75.0 (61.0; 84.0) 24.6 (22.0; 30.0) Influenza A 258 (35.7%) 46 (22.0%) 212 (41.3%) 137/121 (53.1%/46.9%) 72.0 (54.0; 82.0) 26.5 (23.3; 30.0) Influenza B 60 (8.2%) 44 (21.1%) 16 (3.1%) 30/30 (50.0%/50.0%) 6.0 (0.25; 29.0) 22.1 (16.0; 27.3) RSV 107 (14.8%) 73 (34.9%) 34 (6.6%) 57/50 (53.3%/46.7%) 2.0 (0.0; 76.0) 24.2 (21.7; 27.5) RSV + Influenza A 6 (0.8%) 2 (1.0%) 4 (0.8%) 4/2 (66.6%/33.3%) 64.0 (13.0; 87.75) 37.0 (22.1; n.d.) RSV + Influenza B 1 (0.1%) 1 (0.5%) 0 (0.0%) 0/1 (0%/100%) n.d n.d. RSV + SARS 1 (0.1%) 1 (0.5%) 0 (0.0%) 0/1 (0%/100%) n.d. n.d. Influenza A + Influenza B 1 (0.1%) 1 (0.5%) 0 (0.0%) 1/0 (100%/0%) n.d. n.d. Numbers and percentages, or median values and quartiles (in parentheses) are given. n.d. = not determined; BMI = body mass index; a available only in patients of age ≥ 18 years; *percentages refer to the total cohort of 723 patients; **percentages refer to the total number of each age group The majority of patients (40.0%) were infected with SARS-CoV-2, followed by Influenza A (35.7%). RSV infections were less common, accounting for 14.8% of patients, while Influenza B appeared in 8.2%. Co-infections were rare (Table 1 ), so the subsequent statistical analyses were limited to the 714 patients involving single infections with SARS-CoV-2, Influenza A, Influenza B, or RSV. There was no statistically significant difference regarding sex between the four infection groups, however, age showed a difference (p < 0.001). Pairwise, Bonferroni-corrected post hoc comparisons revealed that age differed significantly (p < 0.05 each) between Influenza B versus both, Influenza A and SARS-CoV-2, as well as between RSV versus both, Influenza A and SARS-CoV-2. Figure 1 illustrates the age distribution, showing two distinct peaks at very young and older ages, a pattern already observed in the 2022/23 and 2023/24 seasons [ 3 ], [ 4 ]. In patients of age ≥ 18 years, age again differed between the four infection groups (p < 0.001), median values (quartiles) being 77 (68; 85) years for SARS-CoV-2, 76 (65; 84) years for Influenza A, 52 (32; 77) years for Influenza B, and 84 (76; 87) years for RSV. Post hoc pairwise comparisons with Bonferroni correction indicated significant differences in age (p < 0.05 each) between the four virus types, with the exception of SARS-CoV-2 versus Influenza A. Among patients of age < 18 years, age also showed significant differences between infection groups (p < 0.001). Median values were lowest for SARS-CoV-2, followed by RSV and Influenza A, and highest for Influenza B at 4.5 years. Bonferroni-adjusted pairwise comparisons revealed that only SARS-CoV-2 differed from both, Influenza A and Influenza B (p < 0.05 each). The time course of infections (Supplemental Figure S1 ) showed a peak of SARS-CoV-2 in September and October 2024, when no other infections were present, while Influenza A/B and RSV recognizably started only in the early months of 2025. Influenza A had its peak incidence in January, Influenza B in February, and RSV in March. In the subgroup of patients ≥ 18 years of age, the pattern was similar, and this was also true in patients of age < 18 years, however, the relative frequency of RSV and Influenza B was much larger than in adults. Prevalence of symptoms Analysis was limited to patients aged ≥ 18 years, as symptoms in this group were self-reported and not derived from third-party information as regularly in children. Across the four viral infections, statistically significant differences occurred in the prevalence of cough (p = 0.002), nausea (p = 0.042), and fatigue (p < 0.001) (Supplemental Table S1 ). Cough was most frequently reported with Influenza A (79.7%) and RSV (79.4%), while nausea was most prevalent among patients with Influenza B (31.3%) and fatigue reported most often with SARS-CoV-2 (87.9%). Regarding dyspnoea, fever and diarrhoea, no statistically significant differences between infection groups were found. Logistic regression analyses with symptoms as dependent variable and the confounders age and sex revealed that cough and fatigue remained significantly different between the four infections, while nausea was no more significantly different but dependent on sex, with more symptoms in women. Comorbidities Among the patients aged ≥ 18 years, significant overall differences between the four virus groups were observed only regarding the prevalence of active malignancy within the past five years (p = 0.004) and the presence of immunosuppression (p = 0.004, Table 2 ). Active malignancies were most frequent in patients with Influenza B, whereas immunosuppression was most common in patients with SARS-CoV-2 infection. The number (sum) of comorbidities did not differ significantly between the four groups. Table 2 Prevalence of comorbidities in adult patients ≥ 18 years of age SARS-CoV-2 Influenza A Influenza B RSV P value n 248 212 16 34 - Hypertension 162 (65.3%) 129 (60.8%) 7 (43.8%) 24 (70.6%) 0.234 Peripheral artery disease (PAD) 18 (7.3%) 19 (9.0%) 1 (6.3%) 3 (8.8%) 0.918 Heart failure (HF) 76 (30.6%) 53 (25.0%) 3 (18.8%) 13 (38.2%) 0.256 Coronary artery disease (CAD) 59 (23.8%) 47 (22.2%) 4 (25.0%) 8 (23.5%) 0.958 Diabetes mellitus Type 2 58 (23.4%) 56 (26.4%) 3 (18.8%) 13 (38.2%) 0.279 COPD 30 (12.1%) 41 (19.3%) 1 (6.3%) 3 (8.8%) 0.097 Asthma 13 (5.2%) 24 (11.3%) 2 (12.5%) 4 (11.8%) 0.051 Other lung disease* 15 (6.0%) 7 (3.3%) 2 (12.5%) 0 (0%) 0.111 Chronic kidney disease (CKD) 65 (26.2%) 50 (23.6%) 2 (12.5%) 8 (23.5%) 0.685 Active malignant disease** 60 (24.2%) 25 (11.8%) 4 (25.0%) 5 (14.7%) 0.004 Rheumatic disease 17 (6.9%) 7 (3.3%) 2 (12.5%) 1 (2.9%) 0.144 Depression 10 (4.0%) 9 (4.2%) 0 (0%) 0 (0%) 0.818 Dementia 29 (11.7%) 18 (8.5%) 1 (6.3%) 7 (20.6%) 0.173 State of Immunosuppression 41 (17.3%) 14 (6.6%) 2 (12.5%) 3 (8.8%) 0.004 Number of Comorbidities*** 2.5 (1;4) 2.0 (1;3) 2.0 (0.25;3.75) 3.0 (1;4) 0.235 Given are numbers and percentages, for the sum of comorbidities median values and quartiles. *except malignant lung disease, **within the last 5 years, *** sum of comorbidities from this list. COPD = Chronic obstructive pulmonary disease. Statistical comparisons between the infection groups were performed with the exact test according to Fisher-Freeman-Halton, for the sum using the Kruskal–Wallis test Again, logistic regression analysis was used to clarify, whether the differences in the prevalence of comorbidities were influenced by the confounders age and sex. The differences regarding active malignancy and immunosuppression remained significant and additionally showed a dependence on age (p < 0.01 each) but not on sex. Vital parameters, arterial blood gas and laboratory parameters upon admission Vital signs and laboratory parameters upon admission were analyzed only in patients aged ≥ 18 years (Supplemental Table S3). Among vital signs, only respiratory rate and diastolic blood pressure showed statistically significant differences between the four groups (p < 0.05 each). In blood gas analysis, a significant difference was observed only for pCO₂ (p = 0.023), whereby Bonferroni-adjusted post hoc analysis revealed a difference between SARS-CoV-2 and Influenza A (p < 0.05). Other blood parameters such as CRP, D-dimers and eGFR showed no significant differences between groups. Primary Outcomes ICU admission and in-hospital mortality were compared between viral infections separately for patients aged ≥ 18 years and < 18 years (Table 3 ). Among patients ≥ 18 years of age, there were no statistically significant differences regarding ICU admission (p = 0.976, Fisher-Freeman-Halton test) or mortality (p = 0.059) between the four groups in a 4x2 table. It is noteworthy that mortality was highest for SARS-CoV-2 followed by RSV and about half as high for Influenza A and B (Table 3 ); correspondingly, there was a difference in mortality (p = 0.018) when specifically asking for SARS-CoV-2 and tentatively comparing SARS-CoV-2 with the pooled other infections in a 2x2 table by Fisher’s exact test. In patients of age < 18 years, the number of ICU admissions was low, and no deaths occurred. The low numbers did not allow a meaningful comparison of infection groups. Table 3 ICU admission and mortality stratified according to age group < 18 years ≥ 18 years n ICU admission Mortality n ICU admission Mortality Total Number 204 5 (2.5%) 0 (0.0%) 510 42 (8.2%) 51 (10.0%) SARS-CoV-2 41 2 (4.8%) 0 (0.0%) 248 20 (8.1%) 33 (13.3%) Influenza A 46 0 (0.0%) 0 (0.0%) 212 18 (8.5%) 13 (6.1%) Influenza B 44 2 (4.5%) 0 (0.0%) 16 1 (6.3%) 1 (6.3%) RSV 73 1 (1.5%) 0 (0.0%) 34 3 (8.8%) 4 (11.8%) Numbers and percentages are shown. Mortality refers to in-hospital mortality. ICU = Intensive Care Unit In the study covering the 2022/23 season, data was collected from October to February [ 4 ], and in the 2023/24 study from August to February [ 3 ]. To assess whether the longer observation time of the present study influenced the results, ICU and mortality were additionally analyzed using these shorter time windows (Supplemental Table S2 ). The extension of the observation period was not associated with marked changes regarding ICU admission rate and mortality due to SARS-CoV-2, and similarly for Influenza A. There were small numerical differences regarding RSV which were, however, based on very low case numbers. Secondary endpoints and treatment characteristics Regarding patients aged ≥ 18 years, a tendency for the length of hospital stay being lowest for Influenza B and highest for SARS-CoV-2 was observed but without statistically significant difference (p = 0.050; Table 4 ). Moreover, the length of ICU stay did not differ between infections. Similarly, the rates and durations of mechanical invasive ventilation and non-invasive ventilation (NIV), as well as high-flow and low-flow oxygen supplementation or LTOT upon admission were not significantly different (Table 4 ). However, regarding the presence of any oxygen therapy, i. e. considering any of the aforementioned options, a significant difference was observed (p = 0.046), with the highest proportion observed in RSV and the lowest in Influenza B. Antiviral therapy administration also differed significantly between groups (p < 0.001), with the by far highest proportion seen in Influenza A infections. Table 4 Secondary Endpoints with details of clinical treatment in adult patients ≥ 18 years of age SARS-CoV-2 Influenza A Influenza B RSV P value n 248 212 16 34 - Length of hospital stay, days 7.1 (3.8; 12.4) 5.5 (3.6; 10.0) 3.1 (2.1; 9.2) 6.2 (3.6; 9.3) 0.050 Intensive Care Unit Frequency 20 (8.1%) 18 (8.5%) 1 (6.3%) 3 (8.8%) 0.976 Length of stay, days 5.6 (2.0; 15.2) 4.0 (1.8; 7.4) n.d. 3.0 (1.7; n.d.) 0.300 Mechanical invasive ventilation Frequency 7 (2.8%) 6 (2.8%) 1 (6.3%) 3 (8.8%) 0.073 Duration, days 15.3 (9.7; 21.0) 10.2 (2.3; 35.6) n.d. 1.7 (1.6; n.d.) 0.064 NIV Frequency 8 (3.2%) 8 (3.8%) 0 (0.0%) 0 (0.0%) 0.833 Duration, days 19 (0.4; 4.0) 2.2 (1.5; 3.1) n.d. n.d. 0.792 Oxygen supplementation High-flow during stay 5 (2.0%) 3 (1.4%) 0 (0.0%) 0 (0.0%) 0.883 Low-flow during stay 87 (35.1%) 88 (41.5%) 3 (18,8%) 18 (52,9%) 0.054 LTOT upon admission 22 (8.9%) 13 (6.1%) 1 (6.3%) 2 (5.9%) 0.738 Any oxygen therapy during stay 107 (43.1%) 105 (49.5%) 4 (25.0%) 21 (61.8%) 0.046 Antiviral therapy* 36 (14.5%) 152 (71.7%) 4 (25.0%) n.a. < 0.001 Shown are numbers and percentages, or median values and quartiles (in parentheses). Statistical comparisons between the infection groups were performed with the exact test according to Fisher-Freeman-Halton, for length and duration using the Kruskal–Wallis test. n.d. = not determined; n.a. = not applicable; NIV = non-invasive ventilation; LTOT = long-term oxygen therapy. *Antiviral treatment was used only in Influenza and SARS-CoV-2 infections Slightly different results were observed in patients of age < 18 years (Table 5 ). The length of hospital stay differed significantly across the four groups (p < 0.001), whereby Bonferroni-corrected post hoc analysis revealed significant differences between RSV versus both, SARS-CoV-2 and Influenza B (p ≤ 0.02 each). The longest median stay occurred for RSV. It should be noted, however, that in general stays were short. No statistically significant differences were observed for the length of ICU stay or the use of invasive or non-invasive ventilation. Oxygen therapy showed marked variation regarding both, high-flow and low-flow, oxygen supplementation during hospitalization, as well as any oxygen administration, which were most frequent for RSV (p < 0.001 each). Table 5 Secondary Endpoints with details of clinical treatment in patients < 18 of age SARS-CoV-2 Influenza A Influenza B RSV P value n 41 46 44 73 - Length of hospital stay, days 1.5 (1.1; 2.1) 2.3 (1.7; 3.9) 2.0 (1.1; 3.0) 3.0 (1.9; 4.2) < 0.001 Intensive Care Unit Frequency 2 (4.9%) 0 (0.0%) 2 (4.5%) 1 (1.4%) 0.337 Length of stay, days 1.6 (0.3; n.d.) n.d. 4.3 (0.5; n.d.) n.d. 0.819 Mechanical invasive ventilation Frequency 0 (0.0%) 0 (0.0%) 2 (4.5%) 0 (0.0%) 0.200 Duration, days n.d. n.d. 4.1 (0.5; n.d.) n.d. n.d. NIV Frequency 0 (0.0%) 0 (0.0%) 0 (0.0%) 1 (1.4%) 1.000 Duration, days n.d. n.d. n.d. n.d. n.d. Oxygen supplementation High-flow during stay 2 (4.9%) 0 (0.0%) 1 (2.3%) 14 (19.2%) < 0.001 Low-flow during stay 0 (0.0%) 7 (15.2%) 6 (13.6%) 36 (49.3%) < 0.001 LTOT upon admission 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%) n.d. Any oxygen therapy during stay 2 (4.9%) 7 (15.2%) 9 (20.5%) 51 (69.9%) < 0.001 Antiviral therapy* 0 (0.0%) 2 (4.3%) 2 (4.5%) n.a. 0.116 Shown are numbers and percentages, or median values and quartiles (in parentheses). Statistical comparisons between the infection groups were performed with the exact test according to Fisher-Freeman-Halton, for length and duration using the Kruskal–Wallis test. n.d. = not determined; n.a. = not applicable; NIV = non-invasive ventilation; LTOT = long-term oxygen therapy. *Antiviral treatment was used only in Influenza and SARS-CoV-2 infections RSV immunization of infants The drop of RSV numbers in 2024/25 compared to the two previous years could have been partially due to the recently introduced immunization (Nirsevimab) of infants. To get hints on this possibility, we compared the proportion of immunized infants between RSV and non-RSV infections, expecting that RSV immunization would be less prevalent in infants with RSV infection. Among 27 RSV-infected infants, 25 would have been eligible for immunization and 10 of these (40%) had received the treatment. Among 58 infants with non-RSV infections (Influenza A/B, SARS-CoV-2), 37 would have been eligible and 16 (43%) had undergone immunization. Specifically, for Influenza A/B, 15 of 28 eligible infants (54%), and for SARS-CoV-2, 1 of 9 (11%) had been immunized, whereby the low number for SARS-CoV-2 was due to its high prevalence early after the introduction of immunization. These proportions were not significantly different, thus an effect of RSV immunization on the type of infection in infants was not apparent in our data. Adult RSV vaccination was not consistently documented in our clinical records and therefore could not be assessed. Risk factors for ICU admission and in-hospital death As mentioned above, mortality was highest in adults with SARS-CoV-2 followed closely by RSV infection but the differences did not reach statistical significance (p = 0.059, see above) in unadjusted comparisons of all four infection groups with each other, despite the difference when using pooled values. To reveal whether the inclusion of risk factors as confounders would yield different results, multiple logistic regression analyses were performed. The predictors taken into account included age and sex, CRP, leukocytes, body temperature and blood pressure, and additionally the requirement for oxygen therapy, dyspnoea, fatigue and as comorbidity immunosuppression, in addition to the four types of infections. This choice was based on clinical considerations and the results of the previous analyses (see Tables 2 , 4 and Supplementary Tables S1, S3). The analysis for mortality did still not yield significant associations with the type of infection, however, associations (p < 0.05 each) with dyspnoea, fatigue, systolic blood pressure, body temperature and CRP emerged. Similarly, ICU admission remained un-associated with the type of infection but there were significant relationships to dyspnoea, systolic blood pressure and CRP (p < 0.05 each). Thus, even taking into account multiple patient characteristics as confounders, the observed differences in ICU admission rates and mortality were not statistically associated with specific infections. Transfer of patients During the major phase of COVID-19, inter-hospital transfer rates in the RoMed hospitals were high, placing significant stress on the healthcare system [ 9 ]. To determine whether this persisted, we examined the frequency and underlying reasons for inter-hospital transfers. There were only 16 such transfers attributable to viral infections; 13 transfers occurred from peripheral level 1 care facilities to the level 2 care RoMed Hospital in Rosenheim, of which 5 were due to the requirement for ICU treatment. Additionally, 3 transfers from the level 2 care RoMed Hospital to a Paediatric University Hospital were performed for paediatric intensive care. Compared to the previous data [ 9 ] transfer numbers were much lower, and particularly no transfers due to capacity reasons occurred. Comparison with data from previous seasons As data from three seasons obtained under comparable conditions were available [ 3 ], [ 4 ], a comparison was possible. The Supplemental Figure S2 shows the total number of infections with SARS-CoV-2, Influenza A/B, or RSV as recorded in the seasons 2022/23, 2023/24 and 2024/25. Influenza B appeared in appreciable numbers, especially in the lower age group only in 2024/25. While Influenza A numbers in adults increased, the proportion and number of both RSV in children and SARS-CoV-2 in adults declined over the three years, particularly when taking into account that the present study involved the largest observation window. Of further interest was the time course of infections over the past three seasons, to reveal whether their dynamics had changed (Fig. 2 ). In 2024/25, SARS-CoV-2 had its peak in September/October 2024 and gradually declined, while in 2023/24 numbers were still high in December and in 2022/23 stayed high until February. In contrast, Influenza A and in particular RSV peaks appeared to have shifted towards the spring months over the three years. We also compared mortality in adults between seasons, taking account of the different time windows (Supplemental Table S4). It increased over time for SARS-CoV-2, accompanied by a decrease for Influenza A. In case of RSV, percent mortality was high in 2023/24 but it has to be taken into account that the number was low and thus uncertainty high. When comparing mortality between the three seasons using 3x2 contingency tables for each infection, with or without adjusting the time window, no statistically significant differences were found. We also compared the number and proportion of RSV in infants of age less than 1 year. In 2024/25, among 70 infants, 27 (39%) showed RSV infection, in 2023/24 among 157 infants 86 (55%), and in 2022/23 among 145 infants 102 (70%). This showed a decline in the percentage of RSV already prior to the introduction of immunization that occurred in the autumn of 2024 (p < 0.001). Discussion In the present study, we assessed the prevalence, clinical features and outcomes of patients hospitalized with SARS-CoV-2, Influenza A or B, or RSV infections between August 2024 and April 2025 and compared these findings with data from the previous two seasons. The analysis included patients from all ages admitted to the internal medicine, neurology and paediatrics wards. Compared to the previous two seasons [ 3 ], [ 4 ], the distribution of infection types slightly changed in 2024/25. SARS-CoV-2 (about 40%) and RSV (about 15%) had become less frequent, and Influenza A more frequent (about 36%). Notable numbers of Influenza B (8%) were detected only in 2024/25. As in the previous two seasons, age distribution showed peaks in young children and older adults, whereby infection-specific age differences persisted; RSV was most prevalent below 18 years of age and SARS-CoV-2 at age ≥ 18 years. Cough was most common for Influenza A and RSV, nausea for Influenza B, fatigue for SARS-CoV-2. In adults, ICU admission rates (6–9%) were similar between SARS-CoV-2, Influenza A/B and RSV, while mortality was highest for SARS-CoV-2 (13.3%) and lowest for Influenza A (6.1%) but without significant difference (p = 0.059) when comparing all four infections with each other. Oxygen supplementation, mechanical ventilation and non-invasive ventilation were most frequent for RSV. In patients < 18 years of age, no deaths occurred. ICU admission was most frequent for SARS-CoV-2 and oxygen supplementation for RSV, with low absolute numbers. The distribution of infections showed no major differences compared to the two previous seasons, except that Influenza B re-emerged in substantial numbers. In summary, in the season 2024/25, infections with SARS-CoV-2 were still most frequent in adults, and mortality from SARS-CoV-2 tended to be twice as high as for influenza. When comparing the three years, the proportion and number of SARS-CoV-2 infections in adults and of RSV infections in young patients declined over time. In contrast, Influenza A cases increased among adults (see Supplemental Figure S2 ). The reductions regarding RSV and SARS-CoV-2 occurred despite the extension of the observation period. Influenza B appeared in notable numbers in 2024/25 for the first time over the past three seasons, and in young patients its number was in the range of Influenza A and SARS-CoV-2. These variations compared to the previous years are in line with data from the Germany national registry [ 10 ]. It is of great interest to compare the time course of infections between the three years. The 2024/25 season was characterized by SARS-CoV-2 dominance in early autumn (September–October 2024), followed by peaks of influenza A (January 2025), influenza B (February), and RSV (March) (see Supplemental Figure S1 ). Therefore, the prolongation of the data collection period ensured the acquisition of the peak month of RSV, as well as the temporal decline in Influenza A and B. Compared to the preceding seasons [ 3 ], [ 4 ], SARS-CoV-2 frequency decreased earlier, with almost no new cases being detected after January 2025. In contrast, the Influenza A onset occurred later than previously, roughly in coincidence with Influenza B, while RSV activity progressively shifted to a later period of time. These observations (see Fig. 2 ) demonstrate that the temporal dynamics of infections markedly changed from year to year. It is noteworthy that similar shifts of peak occurrences over three consecutive seasons can also be observed in the reports by the Robert Koch institute [ 11 ], [ 12 ], [ 13 ]. The age distribution was similar to that observed in 2022/23 and 2023/24, showing high numbers in children under 5 years of age and in older individuals, peaking around 85 years of age. Median age was highest in SARS-CoV-2 patients, being 75 years, followed by Influenza A at 72 years. In contrast, RSV and Influenza B predominantly affected younger individuals, with median ages of 2 years and 6 years, respectively. These patterns were consistent with those of the previous two analyses [ 3 ], [ 4 ], [ 14 ], [ 15 ] and international findings [ 3 ], [ 4 ], [ 14 ], [ 15 ] suggesting that probably the characteristics of the viruses did not markedly change over time. Despite many similarities, clinical characteristics showed some differences across infections. As previously [ 3 ], [ 4 ], cough was common with RSV (79%). However, in 2024/25 Influenza A reached the same level (80%). Dyspnea still showed at least a tendency of being most often associated with RSV. These observations are consistent with reports by other investigators [ 16 ], [ 17 ]. Fatigue was frequent across all four viral infections but most prevalent for SARS-CoV-2 (88%). This aligns with the 2022/23 data [ 4 ] but contrasts with the lower rates of only about 10% in 2023/24 [ 3 ] and international studies [ 3 ], [ 16 ]. To which extent such differences are attributable to differences in risk profiles or viral characteristics, cannot be determined from our data. Compared to previous years [ 3 ], [ 4 ], the pattern of comorbidities and their associations with infection types showed differences. Noteworthy, immunosuppression was the only entity associated with a higher risk of infection across all three seasons. However, different viruses played a role, specifically Influenza B in 2024/25, Influenza A in 2023/24, and RSV in 2022/23. In adults, there were no major differences in therapy, although the demand of any oxygen therapy was highest for RSV and least for Influenza B, in concordance with previous data [ 17 ],[ 18 ]. In line with this, the requirement for mechanical invasive ventilation was highest in RSV, again consistent with the previous findings [ 3 ], [ 4 ], despite the lack of statistical significance. Mortality in adults was highest for SARS-CoV-2 and RSV and about half as high for Influenza A and B but due to the low numbers of deceased patients, the differences were not statistically significant at least when comparing all four infections with each other (p = 0.059). This seems of interest since COVID-19 is frequently regarded as having mortality risk comparable to Influenza, as confirmed by us for 2023/24 [ 3 ]. It is noteworthy that data from the Robert Koch Institute for the 2024/25 season indicated in-hospital mortality rates of 18 % or SARS-CoV-2 and 17 % or Influenza [ 10 ] that are higher than in our study. Therefore, potential perceptions considering SARS-CoV-2 infection as a disease of lower importance, either per se or in comparison to Influenza, might be misguided. Mortality was not markedly dependent on the length of the time window chosen for analysis (see Supplemental Table S2 ). The comparison with previous seasons (Supplemental Table S4) indicated that mortality from SARS-CoV-2 even increased over time, while that from Influenza A decreased. In case of RSV, it has to be taken into account that numbers were low and thus uncertainty was high. When varying observation windows, there were also no marked changes regarding ICU admission rate (Supplemental Table S2 ). However, admission rates in 2024/25 were about half the rates of the previous two seasons or even lower [ 3 ], [ 4 ]. Our findings are in line with a large Spanish study conducted between 2021 and 2024, which was, however, limited to people aged ≥ 65 years [ 19 ]. Taken together, they suggest annual changes in mortality and ICU admission rate, which were, however, of the magnitude of previously known variations. The present observations do not allow to decide to which extent there might have been associations with virus variants or protective measures such as the recently established RSV vaccination for older or comorbid patients in Germany. To identify virus-specific risk factors for ICU admission or mortality in the presence of a complex pattern of potential confounders, multiple logistic regression analyses were employed, however, they did not reveal such risk factors. This suggests that with a multiplicity of infections, virus-specific risk factors become more difficult to identify compared to the more homogeneous COVID-19 situation, in which strong risk factors such as renal function could be clearly identified [ 20 ], [ 21 ]. We considered it important to cover the whole spectrum of patients’ ages and therefore included children into our analysis. As in the previous two seasons [ 3 ], [ 4 ], no deaths occurred in this group and the absolute number and rate of ICU admissions was low, without significant differences between infections. ICU admission due to RSV tended to become less frequent but the need for oxygen supplementation remained highest for RSV, in line with other data [ 22 ], [ 23 ], [ 24 ]. Compared to a Hungarian study [ 25 ], however, the rate of oxygen supplementation was much higher in our cohort. Irrespective of these differences, our findings confirm that in young patients RSV has re-appeared in notable numbers, while in 2020 to early 2022 clearly SARS-CoV-2 was dominant [ 8 ]. It also seems noteworthy that the peak of RSV incidence showed a steady shift in time from December in 2022 to March in 2025 (see Fig. 2 and Supplemental Figure S1 ). Since autumn 2024, RSV immunization in Germany includes vaccination for adults aged ≥ 75 years and at-risk individuals aged ≥ 60 years, as well as maternal vaccination and monoclonal antibody prophylaxis for infants [ 7 ]. Based on this, RSV-associated morbidity may be reduced in infants and older adults [ 26 ]. We did not have complete documentation regarding vaccination against RSV, SARS-CoV-2 and Influenza in adults, in contrast to RSV immunization in infants introduced in the autumn of 2024. When comparing the percentages of RSV immunization with RSV versus non-RSV infections, the analysis did not point towards detectable effects of immunization. This does not invalidate the effect of immunization in infants, as the analysis might have occurred too early to detect relevant effects. On the other hand, compared to our previous data [ 3 ], [ 4 ], the number of hospitalized infants (age < 1 year) with RSV infection declined from 102 and 86 to only 27 cases in 2022/23, 2023/24 and 2024/25, respectively, in line with reductions observed in recent analyses of German Registry data [ 27 ]. These analyses also indicated no major changes of RSV infection frequencies in children of age 1 year and older, again in line with our data, as we observed 44, 67, and 37 hospitalized children of age 1–3 years in the three consecutive seasons. Taken together, these observations might be considered as indicating the effectiveness of immunization in infants. A great concern in the COVID-19 pandemic was the stress on the health-care system as reflected in a high rate of inter-hospital transfers, as demonstrated in a previous study [ 9 ]. In the season 2024/25, however, only 16 inter-hospital transfers linked to respiratory viral infections occurred, and no signs of capacity problems requiring transfer were observed. This suggests a return to usual conditions regarding the stress on the health-care system after waning of the COVID-19 pandemic. A key strength is the comparability of data over three consecutive seasons using identical methodology in a single center, while including all age groups and multiple respiratory viruses. All data came from the same primary care hospital, ensuring that patients’ population, medical staff, diagnostic standards and treatment were similar. Compared to the previous two years [ 3 ], [ 4 ], we extended the data collection period to cover the entire season of infections [ 5 ], [ 6 ]. By accounting for the different time periods, comparisons regarding the number, mortality and course of infections could be adjusted. On the other hand, the fact that this investigation was monocentric may limit the generalisability of its findings. Information on vaccination status in adults was not available in a consistent and complete manner. In paediatric patients, symptoms were only documented through third parties, which we deemed as unsuitable for analysis. In a number of paediatric cases, no blood samples were obtained, thus laboratory data were only analyzed in adults. Finally, we had to rely on diagnoses extracted from discharge letters based on ICD-10 coding, in which misclassification due to coding errors cannot be entirely excluded, although it is unlikely. Conclusion The comparison of hospitalizations due to infections with SARS-CoV-2, Influenza A/B, or RSV during the season 2024/25 with the previous two seasons showed that the proportion of SARS-CoV-2 had declined but remained high at 40%. Absolute and relative numbers of RSV infections had decreased in adults as well as young patients including infants. Remarkably, the peak incidence of RSV shifted from December 2022 to March 2025. Moreover, Influenza B re-appeared in significant numbers, particularly in younger patients. SARS-CoV-2, followed by RSV, showed the highest mortality in adults, while that for Influenza was half as high. None of the young patients died. The need for oxygen supplementation was highest with RSV infection. The results not only underline the occurrence and clinical relevance of known respiratory viral infections but also emphasize the ongoing burden from SARS-CoV-2, with variations but no systematic changes of frequency and mortality over three consecutive years. Abbreviations BMI Body Mass Index CAD Coronary artery disease CKD Chronic kidney disease COPD Chronic obstructive pulmonary disease CRP C-reactive protein eGFR Estimated glomerular filtration rate ICU Intensive Care Unit LTOT Long-term oxygen therapy MIV Invasive mechanical ventilation n.d. not determined NIV Non-invasive ventilation PAD Peripheral arterial disease pCO 2 Arterial pressure of carbon dioxide PCR Polymerase Chain Reaction pO 2 Arterial pressures of oxygen RSV Respiratory Syncytial Virus SpO 2 Peripheral oxygen saturation Declarations Ethics approval and consent to participate Approval for this retrospective study was obtained from the Ethics Committee of the University Hospital of Regensburg (Number 25-4131-104) which served as an Institutional Review Board. Moreover, the study was in full accordance with the Declaration of Helsinki. According to the Institutional Review Board, there was no need for patients’ consent to participate in this retrospective analysis of anonymized data. Clinical trial number: not applicable. Consent for publication Not applicable. Availability of data and materials The data set is owned by the authors and not publicly available. It can be shared only by agreement with the authors and consent of the Institutional Review Board (Ethics Committee of the University Hospital of Regensburg). Competing interests The authors declare that they have no competing interests. Funding The study was performed by available resources without specific funding. Authors’ contributions B.T.: Writing and revision of the manuscript, data collection, quality control and analysis; R.A.J.: Writing and revision of the manuscript, data analysis; S.E.: Revision of the manuscript, support in data acquisition; P.A.: Revision of the manuscript, interpretation of the data; K.K.: Revision of the manuscript, interpretation of the data; S.B.: Writing and revision of the manuscript, design of the study, interpretation of the data. Acknowledgements We would like to thank the administration of the RoMed Hospital for their support in the data collection from the files. Authors’ details including first names Benno Trautwein (B.T.) 1 Rudolf A. Jörres (R.A.J.) 2 Sebastian Engelhardt (S.E.) 1 Peter Alter (P.A.) 3 Kathrin Kahnert (K.K.) 4,5 Stephan Budweiser (S.B.) 1,6 1 Department of Internal Medicine III, Division of Pneumology and Respiratory Medicine, RoMed Hospital Rosenheim, Ellmaierstraße 23, 83022 Rosenheim, Germany 2 Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, LMU Hospital, Comprehensive Pneumology Center Munich (CPC-M), Member of the German Center for Lung Research (DZL), Ziemssenstraße 1, 80336 Munich, Germany 3 Department of Medicine, Pulmonary and Critical Care Medicine, University of Marburg (UMR), Germany, Member of the German Center for Lung Research (DZL), Baldingerstraße, 35043 Marburg, Germany 4 MediCenterGermering, Hartstraße 53, 82110 Germering 5 Department of Medicine V, LMU University Hospital, LMU Munich, Comprehensive Pneumology Center Munich (CPC-M), German Center for Lung Research (DZL), Marchioninstraße 15, 81377 München, Germany 6 Department of Internal Medicine II, University Hospital Regensburg, 93053 Regensburg, Germany References Hanage WP, Schaffner W. Burden of Acute Respiratory Infections Caused by Influenza Virus, Respiratory Syncytial Virus, and SARS-CoV-2 with Consideration of Older Adults: A Narrative Review. Infect Dis Ther. Jan. 2025;14:5–37. 10.1007/s40121-024-01080-4 . Feldman C, Anderson R. RSV: an overview of infection in adults. Pneumonia. Jun. 2025;17(1):15. 10.1186/s41479-025-00165-z . Wiechert L, et al. Characteristics and outcomes of patients hospitalized for infection with Influenza A, SARS-CoV-2 or respiratory syncytial virus in the season 2023/2024 in a large German primary care centre. Eur J Med Res. Oct. 2024;29(1):509. 10.1186/s40001-024-02096-9 . Quarg C, Jörres RA, Engelhardt S, Alter P, Budweiser S. Characteristics and outcomes of patients hospitalized for infection with influenza, SARS-CoV-2 or respiratory syncytial virus in the season 2022/2023 in a large German primary care centre. Eur J Med Res. Dec. 2023;28(1). 10.1186/s40001-023-01482-z . Tolksdorf K, et al. Robert Koch-Institut: ARE-Wochenbericht KW 15/2025. Apr. 2025. 10.25646/13099 . Tolksdorf K, et al. Robert Koch-Institut: ARE-Wochenbericht KW 14/2025. Apr. 2025. 10.25646/13091 . Insitute RK. Schutzimpfung und Immunisierung gegen Respiratorische Synzytial-Viren (RSV). Heiland LM, et al. Retrospektive klinisch-kausale Bewertung einer positiven PCR für SARS-CoV-2 bei hospitalisierten Patienten des gesamten Altersspektrums in einem Krankenhaus der Schwerpunktversorgung. Pneumologie. Feb. 2024;78(02):100–6. 10.1055/a-2161-5866 . Suski P, et al. Period of hospitalization and mortality in transferred versus non-transferred COVID-19 patients: results from Germany. Sci Rep. Dec. 2024;14(1). 10.1038/s41598-024-57272-y . Staat D, Tolksdorf K, Schuler E. Krankheitslast von schweren akuten Atemwegserkrankungen (SARI) in der Saison 2024/25 im stationären Bereich, 2025. 10.25646/13338 Buda S et al. Robert Koch-Institut: ARE-Wochenbericht KW 23/2023, 2023. 10.25646/11535 Buda S et al. Robert Koch-Institut: ARE-Wochenbericht KW 23/2024, 2024. 10.25646/12144 Tolksdorf K et al. Robert Koch-Institut: ARE-Monatsbericht KW 21–23/2025, 2025. 10.25646/13175 Korsun N, et al. Resurgence of respiratory syncytial virus with dominance of RSV-B during the 2022–2023 season. Front Microbiol. Apr. 2024;15. 10.3389/fmicb.2024.1376389 . Chauvel C, et al. Community and Hospital-Based Laboratory Surveillance for Influenza, Respiratory Syncytial Virus, and SARS-CoV-2 During the 2023–2024 Season, Lyon, France. J Med Virol. Sep. 2025;97(9):e70549. 10.1002/jmv.70549 . Haeberer M, et al. RSV Risk Profile in Hospitalized Adults and Comparison with Influenza and COVID-19 Controls in Valladolid, Spain, 2010–2022. Infect Dis Ther. Sep. 2024;13(9):1983–99. 10.1007/s40121-024-01021-1 . Surie D, et al. Severity of Respiratory Syncytial Virus vs COVID-19 and Influenza Among Hospitalized US Adults. JAMA Netw Open. Apr. 2024;7(4):e244954. 10.1001/jamanetworkopen.2024.4954 . Clausen CL, et al. Clinical Manifestations and Outcomes in Adults Hospitalized With Respiratory Syncytial Virus and Influenza a/B: A Multicenter Observational Cohort Study. Open Forum Infect Dis. Sep. 2024;11(10). 10.1093/ofid/ofae513 . Vega-Piris L, et al. Severity of respiratory syncytial virus compared with SARS-CoV-2 and influenza among hospitalised adults ≥ 65 years. J Infect. Nov. 2024;89(5):106292. 10.1016/j.jinf.2024.106292 . Kurzeder L et al. Oct., A simple risk score for mortality including the PCR Ct value upon admission in patients hospitalized due to COVID-19., Infection , vol. 50, no. 5, pp. 1155–1163, 2022, 10.1007/s15010-022-01783-1 Budweiser S, et al. Patients’ treatment limitations as predictive factor for mortality in COVID-19: results from hospitalized patients of a hotspot region for SARS-CoV-2 infections. Respir Res. Jun. 2021;22(1):168. 10.1186/s12931-021-01756-2 . K. M. Andersen et al., Clinical Outcomes in Children <5 Years of Age Hospitalized for Respiratory Syncytial Virus, COVID-19 or Influenza in the United States, Pediatric Infectious Disease Journal , May 2025, doi: 10.1097/INF.0000000000004866. Kurz H, et al. Respiratory Syncytial Virus and Influenza During the COVID-19 Pandemic: A Two-center Experience. Pediatr Infect Dis J. May 2024;43(5):410–4. 10.1097/INF.0000000000004260 . Kurz H, Hoffmann H, Oeser R, Resch B. Burden of disease and seasonal data of children hospitalized due to RSV and Influenza infection before, during and after the COVID-19 pandemic. Eur J Pediatr. Jun. 2025;184(7):459. 10.1007/s00431-025-06289-0 . Orosz N, Gömöri G, Battamir U, Nagy AC. Hospital-based cross-sectional study on the clinical characteristics of children with severe acute respiratory infections in Hungary. BMC Infect Dis. Nov. 2024;24(1):1268. 10.1186/s12879-024-10186-6 . Krauer F, et al. Effectiveness and efficiency of immunisation strategies to prevent RSV among infants and older adults in Germany: a modelling study. BMC Med. Oct. 2024;22(1):478. 10.1186/s12916-024-03687-3 . Schönfeld V, Rau C, Cai W, Wichmann O, Harder T. The incidence of RSV infection since the introduction of monoclonal antibody prophylaxis. Dtsch Arztebl Int Aug. 2025. 10.3238/arztebl.m2025.0111 . Acknowledgements We would. like to thank the administration of the RoMed Hospital for their support in data collection from the files. Authors' contributions BT. Writing and revision of the manuscript, data collection, quality control and analysis; RAJ: Writing and revision of the manuscript, data analysis; SE: Revision of the manuscript, support in data acquisition; PA: Revision of the manuscript, interpretation of the data; KK: Revision of the manuscript, interpretation of the data; SB: Writing and revision of the manuscript, design of the study, interpretation of the data. Additional Declarations No competing interests reported. Supplementary Files SupplementalTablesfinal.docx SupplementalFiguresFinal.pptx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 13 Apr, 2026 Reviews received at journal 10 Apr, 2026 Reviewers agreed at journal 02 Apr, 2026 Reviewers agreed at journal 09 Mar, 2026 Reviews received at journal 03 Mar, 2026 Reviewers agreed at journal 09 Feb, 2026 Reviewers agreed at journal 08 Jan, 2026 Reviewers invited by journal 06 Jan, 2026 Editor invited by journal 26 Dec, 2025 Editor assigned by journal 22 Dec, 2025 Submission checks completed at journal 22 Dec, 2025 First submitted to journal 19 Dec, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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07:19:17","extension":"docx","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":17277,"visible":true,"origin":"","legend":"","description":"","filename":"Table5Trautwein.docx","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/4353dd55c6aa346bd2a7e727.docx"},{"id":100357743,"identity":"33df4cca-f206-40bd-8284-3abccfaecf4c","added_by":"auto","created_at":"2026-01-16 07:20:16","extension":"json","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":8693,"visible":true,"origin":"","legend":"","description":"","filename":"c06fe4528094440d86194c565b8d2291.json","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/a18183bb4d4a290fb80266f1.json"},{"id":100357460,"identity":"980fa578-72f0-4920-a9d6-e171c69c3456","added_by":"auto","created_at":"2026-01-16 07:19:53","extension":"pptx","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":128011,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementalFiguresFinal.pptx","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/d4b45bb9907d7cf808095bea.pptx"},{"id":99859122,"identity":"d55eaa65-27ce-48cc-b8f9-b9196a451cd0","added_by":"auto","created_at":"2026-01-09 06:37:41","extension":"docx","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":63601,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementalTablesfinal.docx","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/255fe90fff38594c44a81165.docx"},{"id":100357771,"identity":"d59e51bb-6460-4ddd-b2ce-66b963466b72","added_by":"auto","created_at":"2026-01-16 07:20:18","extension":"xml","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":143437,"visible":true,"origin":"","legend":"","description":"","filename":"c06fe4528094440d86194c565b8d22911enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/05b1927d3bd22e0f38fe06a3.xml"},{"id":100357681,"identity":"48365341-765b-47c5-9d57-1b53816a3617","added_by":"auto","created_at":"2026-01-16 07:20:10","extension":"pptx","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":100480,"visible":true,"origin":"","legend":"","description":"","filename":"Figure1Trautwein.pptx","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/3135a406eb2eb5a932c01f45.pptx"},{"id":99859121,"identity":"e3e7e717-1c16-479b-8074-7115c17b179a","added_by":"auto","created_at":"2026-01-09 06:37:41","extension":"pptx","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":52222,"visible":true,"origin":"","legend":"","description":"","filename":"Figure2Trautwein.pptx","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/a885129b8817fdd56aa074fb.pptx"},{"id":99859124,"identity":"03495f0e-739c-4f46-b044-284b2dae7df3","added_by":"auto","created_at":"2026-01-09 06:37:41","extension":"xml","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":145645,"visible":true,"origin":"","legend":"","description":"","filename":"c06fe4528094440d86194c565b8d22911structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/19df0eeae3f879e9303ddcad.xml"},{"id":100357360,"identity":"be092f35-95e8-4ac9-8555-510b572b0622","added_by":"auto","created_at":"2026-01-16 07:19:45","extension":"html","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":157107,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/402723aabc86a7e41db42aa4.html"},{"id":99859109,"identity":"09218985-d6d9-465b-95d4-d38a1662b20b","added_by":"auto","created_at":"2026-01-09 06:37:41","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":197510,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of age in hospitalized patients stratified for infection type. Absolute numbers are shown for each age category comprising a 5 years interval. The numbers refer to the whole observation period from August 1\u003csup\u003est\u003c/sup\u003e, 2024 to April 30\u003csup\u003eth\u003c/sup\u003e, 2025\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/0e2debb0b3daf61b1110ae09.jpg"},{"id":99859110,"identity":"8dc50b92-1a43-436c-a764-9d904193c951","added_by":"auto","created_at":"2026-01-09 06:37:41","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":89580,"visible":true,"origin":"","legend":"\u003cp\u003eTime course of infections over the last three seasons [3], [4]. Number of admitted patients versus month, comparing each type of infection in the last three years. Absolute numbers are shown. Please note the different observation windows: 2022/23 October – February; 2023/24 August – February; 2024/25 August – April\u003c/p\u003e","description":"","filename":"Figure2Trautwein.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/61cbb5fbdbdabc4675d05e43.jpg"},{"id":100377018,"identity":"95c54671-89fb-4eb0-92d1-df4aab965c66","added_by":"auto","created_at":"2026-01-16 08:46:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1762115,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/ee51ed63-6a6c-49b3-a3e5-30de134ce86b.pdf"},{"id":100357721,"identity":"a8e5aefa-af94-4a7c-9310-640e9812556e","added_by":"auto","created_at":"2026-01-16 07:20:15","extension":"docx","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":63601,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementalTablesfinal.docx","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/1708ba522555d02c753dd9b7.docx"},{"id":100357210,"identity":"400f4fbe-2058-42e2-a9a8-63030e9dea57","added_by":"auto","created_at":"2026-01-16 07:19:19","extension":"pptx","order_by":6,"title":"","display":"","copyAsset":false,"role":"supplement","size":128011,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementalFiguresFinal.pptx","url":"https://assets-eu.researchsquare.com/files/rs-8402845/v1/37029884c8254e31e0315333.pptx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Clinical course of hospitalizations with Influenza, SARS-CoV-2 and respiratory syncytial virus (RSV) infections in the season 2024/2025 in a large German primary care centre and comparison with the previous two years","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSeasonal respiratory viruses such as influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 continue to pose a significant public health burden, particularly in older adults and small children and predominately during the winter months, contributing to the number of hospitalizations and mortality [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Subsequent to the COVID-19 pandemic, the epidemiological characteristics of these infections have changed with regard to their prevalence, outcomes and risk profiles [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In two previous studies [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] we utilized data from a large German primary care hospital, to assess the characteristics and outcomes of patients hospitalized with influenza A, SARS-CoV-2, or RSV during the 2022/23 and 2023/24 seasons, with the aim to enable longitudinal comparisons through consistent methodology and data collection.\u003c/p\u003e \u003cp\u003eThe first study addressed the dynamics after the end of the dominance of SARS-CoV-2 and the re-emergence of \u0026ldquo;classical\u0026rdquo; respiratory viruses such as influenza A and RSV [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The second study extended this investigation to the following season, seeking to identify whether and in which way the situation had changed within one year [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Both analyses provided valuable data on the prevalence and relevance of respiratory viral infections after the COVID-19 pandemic.\u003c/p\u003e \u003cp\u003eThe present study continues this line of research by examining the 2024/25 season, based on the fact that trajectories of respiratory virus activity remain unpredictable and either new trends may have emerged or previously observed patterns may have become stable. To further ensure comparability, patient characteristics and clinical outcomes were assessed using the same methodology as in the previous two seasons.\u003c/p\u003e \u003cp\u003eHowever, the observation period was extended to the time from August 2024 to April 2025, corresponding to the surveillance window used by the German Robert Koch-Institute (RKI) for 2024/25. According to its reports, influenza and RSV activity persisted beyond February, whereby the influenza wave was terminated only in week 14/2025 and the RSV wave in week 15/2025 [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. To facilitate comparisons with previous seasons, we performed sub-analyses with shorter time windows as used in our previous studies [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Moreover, the RSV immunization in infants and vaccination in adults as recently established in Germany introduced a new factor that may have influenced the clinical outcome [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBased on these considerations, the present study assessed the clinical characteristics and outcomes of patients of all ages hospitalized due to acute respiratory viral infections in a large primary care hospital in southern Germany in 2024/25 and compared the results with those of the previous two seasons.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy population\u003c/h2\u003e \u003cp\u003eThis retrospective analysis used data of hospitalized patients of all ages collected at the RoMed Hospital Rosenheim, Bavaria, Germany, between August 1st, 2024, and April 30th, 2025. This primary-care hospital covers a population of approximately 320.000 inhabitants. If there was any clinical suspicion on the presence of a viral infection, a multiplex PCR test for SARS-CoV-2, Influenza A/B, and RSV was performed. Consequently, patients with confirmed PCR-positive results for SARS-CoV-2, Influenza A/B, RSV, or co-infections involving these viruses were included. If patients were re-admitted within 4 weeks for the same infection, only the first admission was chosen. This resulted in 825 patients. In the next step, we aimed to exclude patients in whom the likelihood that the infection was incidental and not causally related to hospitalization was high. Thus, based on previous experience [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] and in agreement with our previous analyses [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], specialties such as gynaecology, surgery, and urology were excluded (n\u0026thinsp;=\u0026thinsp;102), and we selected only patients admitted to the departments of internal medicine, neurology and paediatrics. This resulted in a final study population of 723 patients.\u003c/p\u003e \u003cp\u003e Approval for this retrospective study was obtained from the Ethics Committee of the University Hospital of Regensburg (Number 25-4131-104) which served as an Institutional Review Board. Moreover, the study was in full accordance with the Declaration of Helsinki. According to the Institutional Review Board, there was no need for patients\u0026rsquo; consent to participate in this retrospective analysis of anonymized data. \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eClinical trial number: not applicable\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eAssessments\u003c/h3\u003e\n\u003cp\u003eThe presence and type of infection were determined by PCR (polymerase chain reaction) testing, conducted either upon hospital admission or during the inpatient stay. For the 2024/25 season, the PCR assays employed were the STANDARD\u0026trade; M10 SARS-CoV-2 and STANDARD\u0026trade; M10 FLU/RSV/SARS-CoV-2 kits (SD BIOSENSOR, INC., Suwon, Republic of Korea) that covered all infections addressed in the present study. In case of invalid or inconclusive results, confirmation was achieved through repeated testing, either using the same multiplex assay or its virus-specific version. Clinical and laboratory data were extracted using the KIS Medico software package (Version 29, CGM Clinical Europe GmbH, Koblenz, Germany), and additional information was taken from the written clinical reports of each patient.\u003c/p\u003e \u003cp\u003eThe collected data included age, sex, body mass index (BMI), and a range of comorbidities comprising hypertension, coronary artery disease, diabetes mellitus type 2, COPD, asthma and other common diseases from internal medicine, similar as in the previous studies [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Symptoms upon admission encompassed cough, dyspnea, fatigue, fever, diarrhea, and nausea. Vital signs included systolic and diastolic blood pressure, respiratory rate, heart rate, body temperature, and peripheral oxygen saturation (SpO\u003csub\u003e2\u003c/sub\u003e). Laboratory analyses on admission were based on peripheral venous blood samples and comprised estimated glomerular filtration rate (eGFR) computed from creatinine, C-reactive protein (CRP), and D-dimers. Blood gas parameters included pH, as well as arterial partial pressures of oxygen (pO\u003csub\u003e2\u003c/sub\u003e) and carbon dioxide (pCO\u003csub\u003e2\u003c/sub\u003e). All of these variables referred to the patients\u0026rsquo; state upon admission. Furthermore, the application of antiviral treatment and the presence of RSV immunization in infants were assessed.\u003c/p\u003e\n\u003ch3\u003eOutcomes\u003c/h3\u003e\n\u003cp\u003eThe primary outcomes selected for the comparison between infection types were ICU (intensive care unit) admission and in-hospital mortality. Secondary outcomes were respiratory support including the administration of invasive mechanical ventilation, non-invasive ventilation (NIV), as well as high-flow and low-flow oxygen therapy. High-flow oxygen therapy (HFNC, high flow nasal cannula) was delivered via cannula or Venturi mask with flow rates ranging from 30 to 60 L/min, whereas low-flow oxygen therapy was provided at flow rates between 2 and 6 L/min using either a simple face mask or nasal cannula. In addition, length of hospital and intensive care unit stay, and antiviral treatment were assessed.\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eData analysis\u003c/h2\u003e \u003cp\u003eDescriptive statistics are presented as counts and percentages, or as median values with quartiles, depending on the data type. To compare infection categories, either the (exact) Fisher-Freeman-Halton test or the Kruskal-Wallis analysis of variance was applied, as appropriate. If the Kruskal-Wallis test indicated significant differences, post hoc pairwise comparisons were conducted using the Mann-Whitney U-test with Bonferroni corrections to adjust for multiple testing. The Fisher-Freeman-Halton test was also used to compare data between the three seasons. Correspondingly, Fisher\u0026rsquo;s exact test for 2x2 tables was used to reveal potential effects of RSV immunization in infants.\u003c/p\u003e \u003cp\u003eLogistic regression analysis was employed to determine whether the associations of symptoms or comorbidities with infection type were influenced by patients\u0026rsquo; age and sex. In addition, logistic regression analyses were performed to identify and quantify potential associations between primary outcomes and patient characteristics and infection types. A two-sided p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant. All statistical analyses were conducted using the SPSS software (version 31; IBM Corporation, Armonk, NY, USA).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eAnthropometric data and distribution of infections\u003c/h2\u003e \u003cp\u003eOut of 825 patients across all departments, 723 patients from the departments of internal medicine, paediatrics or neurology remained for analyses (337 women (46.6%), 386 men (53.4%)). Median (quartiles) age and BMI were 69.0 (6.0; 81.0) years and 25.3 (22.5, 29.7) kg/m\u0026sup2;, respectively (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBaseline characteristics of each type of viral infection\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNumber *\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN (\u0026lt;\u0026thinsp;18 years)**\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003en (\u0026ge;\u0026thinsp;18 years)**\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSex (m/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e )\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTotal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e723\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e209 (28.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e514 (71.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e386/337 (53.4%/46.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e69.0 (6.0; 81.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e25.3 (22.5; 29.7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSARS-CoV-2\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e289 (40.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e41 (19.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e248 (48.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e157/132 (54.3%/45.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e75.0 (61.0; 84.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e24.6 (22.0; 30.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInfluenza A\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e258 (35.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e46 (22.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e212 (41.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e137/121 (53.1%/46.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e72.0 (54.0; 82.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e26.5 (23.3; 30.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInfluenza B\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60 (8.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e44 (21.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e16 (3.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30/30 (50.0%/50.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6.0 (0.25; 29.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e22.1 (16.0; 27.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRSV\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e107 (14.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e73 (34.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e34 (6.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e57/50 (53.3%/46.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.0 (0.0; 76.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e24.2 (21.7; 27.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRSV\u0026thinsp;+\u0026thinsp;Influenza A\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6 (0.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2 (1.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4 (0.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4/2 (66.6%/33.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e64.0 (13.0; 87.75)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e37.0 (22.1; n.d.)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRSV\u0026thinsp;+\u0026thinsp;Influenza B\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (0.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1 (0.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0/1 (0%/100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003en.d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRSV\u0026thinsp;+\u0026thinsp;SARS\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (0.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1 (0.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0/1 (0%/100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInfluenza A\u0026thinsp;+\u0026thinsp;Influenza B\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (0.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1 (0.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1/0 (100%/0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003eNumbers and percentages, or median values and quartiles (in parentheses) are given. n.d. = not determined; BMI\u0026thinsp;=\u0026thinsp;body mass index; \u003csup\u003ea\u003c/sup\u003e available only in patients of age\u0026thinsp;\u0026ge;\u0026thinsp;18 years; *percentages refer to the total cohort of 723 patients; **percentages refer to the total number of each age group\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe majority of patients (40.0%) were infected with SARS-CoV-2, followed by Influenza A (35.7%). RSV infections were less common, accounting for 14.8% of patients, while Influenza B appeared in 8.2%. Co-infections were rare (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), so the subsequent statistical analyses were limited to the 714 patients involving single infections with SARS-CoV-2, Influenza A, Influenza B, or RSV.\u003c/p\u003e \u003cp\u003eThere was no statistically significant difference regarding sex between the four infection groups, however, age showed a difference (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Pairwise, Bonferroni-corrected post hoc comparisons revealed that age differed significantly (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 each) between Influenza B versus both, Influenza A and SARS-CoV-2, as well as between RSV versus both, Influenza A and SARS-CoV-2. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e illustrates the age distribution, showing two distinct peaks at very young and older ages, a pattern already observed in the 2022/23 and 2023/24 seasons [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn patients of age\u0026thinsp;\u0026ge;\u0026thinsp;18 years, age again differed between the four infection groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), median values (quartiles) being 77 (68; 85) years for SARS-CoV-2, 76 (65; 84) years for Influenza A, 52 (32; 77) years for Influenza B, and 84 (76; 87) years for RSV. Post hoc pairwise comparisons with Bonferroni correction indicated significant differences in age (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 each) between the four virus types, with the exception of SARS-CoV-2 versus Influenza A.\u003c/p\u003e \u003cp\u003eAmong patients of age\u0026thinsp;\u0026lt;\u0026thinsp;18 years, age also showed significant differences between infection groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Median values were lowest for SARS-CoV-2, followed by RSV and Influenza A, and highest for Influenza B at 4.5 years. Bonferroni-adjusted pairwise comparisons revealed that only SARS-CoV-2 differed from both, Influenza A and Influenza B (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 each).\u003c/p\u003e \u003cp\u003eThe time course of infections (Supplemental Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e) showed a peak of SARS-CoV-2 in September and October 2024, when no other infections were present, while Influenza A/B and RSV recognizably started only in the early months of 2025. Influenza A had its peak incidence in January, Influenza B in February, and RSV in March. In the subgroup of patients\u0026thinsp;\u0026ge;\u0026thinsp;18 years of age, the pattern was similar, and this was also true in patients of age\u0026thinsp;\u0026lt;\u0026thinsp;18 years, however, the relative frequency of RSV and Influenza B was much larger than in adults.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePrevalence of symptoms\u003c/h3\u003e\n\u003cp\u003eAnalysis was limited to patients aged\u0026thinsp;\u0026ge;\u0026thinsp;18 years, as symptoms in this group were self-reported and not derived from third-party information as regularly in children. Across the four viral infections, statistically significant differences occurred in the prevalence of cough (p\u0026thinsp;=\u0026thinsp;0.002), nausea (p\u0026thinsp;=\u0026thinsp;0.042), and fatigue (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) (Supplemental Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). Cough was most frequently reported with Influenza A (79.7%) and RSV (79.4%), while nausea was most prevalent among patients with Influenza B (31.3%) and fatigue reported most often with SARS-CoV-2 (87.9%). Regarding dyspnoea, fever and diarrhoea, no statistically significant differences between infection groups were found.\u003c/p\u003e \u003cp\u003eLogistic regression analyses with symptoms as dependent variable and the confounders age and sex revealed that cough and fatigue remained significantly different between the four infections, while nausea was no more significantly different but dependent on sex, with more symptoms in women.\u003c/p\u003e\n\u003ch3\u003eComorbidities\u003c/h3\u003e\n\u003cp\u003eAmong the patients aged\u0026thinsp;\u0026ge;\u0026thinsp;18 years, significant overall differences between the four virus groups were observed only regarding the prevalence of active malignancy within the past five years (p\u0026thinsp;=\u0026thinsp;0.004) and the presence of immunosuppression (p\u0026thinsp;=\u0026thinsp;0.004, Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Active malignancies were most frequent in patients with Influenza B, whereas immunosuppression was most common in patients with SARS-CoV-2 infection. The number (sum) of comorbidities did not differ significantly between the four groups.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePrevalence of comorbidities in adult patients\u0026thinsp;\u0026ge;\u0026thinsp;18 years of age\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSARS-CoV-2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eInfluenza A\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eInfluenza B\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRSV\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003en\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e248\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e212\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHypertension\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e162 (65.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e129 (60.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (43.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e24 (70.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.234\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePeripheral artery disease (PAD)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18 (7.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19 (9.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (6.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3 (8.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.918\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHeart failure (HF)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e76 (30.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53 (25.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 (18.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13 (38.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.256\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCoronary artery disease (CAD)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59 (23.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e47 (22.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4 (25.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8 (23.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.958\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDiabetes mellitus Type 2\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e58 (23.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e56 (26.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 (18.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13 (38.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.279\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCOPD\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30 (12.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41 (19.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (6.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3 (8.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.097\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAsthma\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13 (5.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24 (11.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (12.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4 (11.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.051\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOther lung disease*\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15 (6.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (3.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (12.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.111\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eChronic kidney disease (CKD)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e65 (26.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50 (23.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (12.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8 (23.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.685\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eActive malignant disease**\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60 (24.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25 (11.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4 (25.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5 (14.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRheumatic disease\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17 (6.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (3.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (12.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1 (2.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.144\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDepression\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (4.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9 (4.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.818\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDementia\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29 (11.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18 (8.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (6.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7 (20.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.173\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eState of Immunosuppression\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41 (17.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14 (6.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (12.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3 (8.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNumber of Comorbidities***\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.5 (1;4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.0 (1;3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.0 (0.25;3.75)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.0 (1;4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.235\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eGiven are numbers and percentages, for the sum of comorbidities median values and quartiles. *except malignant lung disease, **within the last 5 years, *** sum of comorbidities from this list. COPD\u0026thinsp;=\u0026thinsp;Chronic obstructive pulmonary disease. Statistical comparisons between the infection groups were performed with the exact test according to Fisher-Freeman-Halton, for the sum using the Kruskal\u0026ndash;Wallis test\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAgain, logistic regression analysis was used to clarify, whether the differences in the prevalence of comorbidities were influenced by the confounders age and sex. The differences regarding active malignancy and immunosuppression remained significant and additionally showed a dependence on age (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01 each) but not on sex.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eVital parameters, arterial blood gas and laboratory parameters upon admission\u003c/h2\u003e \u003cp\u003eVital signs and laboratory parameters upon admission were analyzed only in patients aged\u0026thinsp;\u0026ge;\u0026thinsp;18 years (Supplemental Table S3). Among vital signs, only respiratory rate and diastolic blood pressure showed statistically significant differences between the four groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 each). In blood gas analysis, a significant difference was observed only for pCO₂ (p\u0026thinsp;=\u0026thinsp;0.023), whereby Bonferroni-adjusted post hoc analysis revealed a difference between SARS-CoV-2 and Influenza A (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Other blood parameters such as CRP, D-dimers and eGFR showed no significant differences between groups.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003ePrimary Outcomes\u003c/h2\u003e \u003cp\u003eICU admission and in-hospital mortality were compared between viral infections separately for patients aged\u0026thinsp;\u0026ge;\u0026thinsp;18 years and \u0026lt;\u0026thinsp;18 years (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Among patients\u0026thinsp;\u0026ge;\u0026thinsp;18 years of age, there were no statistically significant differences regarding ICU admission (p\u0026thinsp;=\u0026thinsp;0.976, Fisher-Freeman-Halton test) or mortality (p\u0026thinsp;=\u0026thinsp;0.059) between the four groups in a 4x2 table. It is noteworthy that mortality was highest for SARS-CoV-2 followed by RSV and about half as high for Influenza A and B (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e); correspondingly, there was a difference in mortality (p\u0026thinsp;=\u0026thinsp;0.018) when specifically asking for SARS-CoV-2 and tentatively comparing SARS-CoV-2 with the pooled other infections in a 2x2 table by Fisher\u0026rsquo;s exact test. In patients of age\u0026thinsp;\u0026lt;\u0026thinsp;18 years, the number of ICU admissions was low, and no deaths occurred. The low numbers did not allow a meaningful comparison of infection groups.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eICU admission and mortality stratified according to age group\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;18 years\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c8\" namest=\"c5\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;18 years\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eICU admission\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eMortality\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eICU admission\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMortality\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTotal Number\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e204\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (2.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e510\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e42 (8.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e51 (10.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSARS-CoV-2\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (4.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e248\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e20 (8.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e33 (13.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInfluenza A\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e212\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e18 (8.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e13 (6.1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInfluenza B\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (4.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1 (6.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1 (6.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRSV\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (1.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3 (8.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e4 (11.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"8\"\u003eNumbers and percentages are shown. Mortality refers to in-hospital mortality. ICU\u0026thinsp;=\u0026thinsp;Intensive Care Unit\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn the study covering the 2022/23 season, data was collected from October to February [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], and in the 2023/24 study from August to February [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. To assess whether the longer observation time of the present study influenced the results, ICU and mortality were additionally analyzed using these shorter time windows (Supplemental Table \u003cspan refid=\"MOESM2\" class=\"InternalRef\"\u003eS2\u003c/span\u003e). The extension of the observation period was not associated with marked changes regarding ICU admission rate and mortality due to SARS-CoV-2, and similarly for Influenza A. There were small numerical differences regarding RSV which were, however, based on very low case numbers.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eSecondary endpoints and treatment characteristics\u003c/h2\u003e \u003cp\u003eRegarding patients aged\u0026thinsp;\u0026ge;\u0026thinsp;18 years, a tendency for the length of hospital stay being lowest for Influenza B and highest for SARS-CoV-2 was observed but without statistically significant difference (p\u0026thinsp;=\u0026thinsp;0.050; Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Moreover, the length of ICU stay did not differ between infections. Similarly, the rates and durations of mechanical invasive ventilation and non-invasive ventilation (NIV), as well as high-flow and low-flow oxygen supplementation or LTOT upon admission were not significantly different (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). However, regarding the presence of any oxygen therapy, i. e. considering any of the aforementioned options, a significant difference was observed (p\u0026thinsp;=\u0026thinsp;0.046), with the highest proportion observed in RSV and the lowest in Influenza B. Antiviral therapy administration also differed significantly between groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), with the by far highest proportion seen in Influenza A infections.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSecondary Endpoints with details of clinical treatment in adult patients\u0026thinsp;\u0026ge;\u0026thinsp;18 years of age\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSARS-CoV-2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eInfluenza A\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eInfluenza B\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRSV\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e248\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e212\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLength of hospital stay, days\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.1 (3.8; 12.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.5 (3.6; 10.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.1 (2.1; 9.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.2 (3.6; 9.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.050\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIntensive Care Unit\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFrequency\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20 (8.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18 (8.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (6.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3 (8.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.976\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLength of stay, days\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.6 (2.0; 15.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.0 (1.8; 7.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.0 (1.7; n.d.)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.300\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMechanical invasive ventilation\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFrequency\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (2.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (2.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (6.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3 (8.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.073\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDuration, days\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15.3 (9.7; 21.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.2 (2.3; 35.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.7 (1.6; n.d.)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.064\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNIV\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFrequency\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8 (3.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (3.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.833\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDuration, days\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19 (0.4; 4.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.2 (1.5; 3.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.792\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOxygen supplementation\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHigh-flow during stay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 (2.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (1.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.883\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLow-flow during stay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e87 (35.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e88 (41.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 (18,8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e18 (52,9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.054\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLTOT upon admission\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (8.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13 (6.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (6.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.738\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAny oxygen therapy during stay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e107 (43.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e105 (49.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4 (25.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e21 (61.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.046\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAntiviral therapy*\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e36 (14.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e152 (71.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4 (25.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003en.a.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eShown are numbers and percentages, or median values and quartiles (in parentheses). Statistical comparisons between the infection groups were performed with the exact test according to Fisher-Freeman-Halton, for length and duration using the Kruskal\u0026ndash;Wallis test. n.d. = not determined; n.a. = not applicable; NIV\u0026thinsp;=\u0026thinsp;non-invasive ventilation; LTOT\u0026thinsp;=\u0026thinsp;long-term oxygen therapy. *Antiviral treatment was used only in Influenza and SARS-CoV-2 infections\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eSlightly different results were observed in patients of age\u0026thinsp;\u0026lt;\u0026thinsp;18 years (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The length of hospital stay differed significantly across the four groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), whereby Bonferroni-corrected post hoc analysis revealed significant differences between RSV versus both, SARS-CoV-2 and Influenza B (p\u0026thinsp;\u0026le;\u0026thinsp;0.02 each). The longest median stay occurred for RSV. It should be noted, however, that in general stays were short. No statistically significant differences were observed for the length of ICU stay or the use of invasive or non-invasive ventilation. Oxygen therapy showed marked variation regarding both, high-flow and low-flow, oxygen supplementation during hospitalization, as well as any oxygen administration, which were most frequent for RSV (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001 each).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSecondary Endpoints with details of clinical treatment in patients\u0026thinsp;\u0026lt;\u0026thinsp;18 of age\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSARS-CoV-2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eInfluenza A\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eInfluenza B\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRSV\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLength of hospital stay, days\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.5 (1.1; 2.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.3 (1.7; 3.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.0 (1.1; 3.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.0 (1.9; 4.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIntensive Care Unit\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFrequency\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (4.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (4.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1 (1.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.337\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLength of stay, days\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.6 (0.3; n.d.)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.3 (0.5; n.d.)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.819\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMechanical invasive ventilation\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFrequency\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (4.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.200\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDuration, days\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.1 (0.5; n.d.)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNIV\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFrequency\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1 (1.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDuration, days\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOxygen supplementation\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHigh-flow during stay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (4.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (2.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14 (19.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLow-flow during stay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (15.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6 (13.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e36 (49.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLTOT upon admission\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003en.d.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAny oxygen therapy during stay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (4.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (15.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9 (20.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e51 (69.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAntiviral therapy*\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (4.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (4.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003en.a.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.116\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eShown are numbers and percentages, or median values and quartiles (in parentheses). Statistical comparisons between the infection groups were performed with the exact test according to Fisher-Freeman-Halton, for length and duration using the Kruskal\u0026ndash;Wallis test. n.d. = not determined; n.a. = not applicable; NIV\u0026thinsp;=\u0026thinsp;non-invasive ventilation; LTOT\u0026thinsp;=\u0026thinsp;long-term oxygen therapy. *Antiviral treatment was used only in Influenza and SARS-CoV-2 infections\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eRSV immunization of infants\u003c/h2\u003e \u003cp\u003eThe drop of RSV numbers in 2024/25 compared to the two previous years could have been partially due to the recently introduced immunization (Nirsevimab) of infants. To get hints on this possibility, we compared the proportion of immunized infants between RSV and non-RSV infections, expecting that RSV immunization would be less prevalent in infants with RSV infection. Among 27 RSV-infected infants, 25 would have been eligible for immunization and 10 of these (40%) had received the treatment. Among 58 infants with non-RSV infections (Influenza A/B, SARS-CoV-2), 37 would have been eligible and 16 (43%) had undergone immunization. Specifically, for Influenza A/B, 15 of 28 eligible infants (54%), and for SARS-CoV-2, 1 of 9 (11%) had been immunized, whereby the low number for SARS-CoV-2 was due to its high prevalence early after the introduction of immunization. These proportions were not significantly different, thus an effect of RSV immunization on the type of infection in infants was not apparent in our data. Adult RSV vaccination was not consistently documented in our clinical records and therefore could not be assessed.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eRisk factors for ICU admission and in-hospital death\u003c/h2\u003e \u003cp\u003eAs mentioned above, mortality was highest in adults with SARS-CoV-2 followed closely by RSV infection but the differences did not reach statistical significance (p\u0026thinsp;=\u0026thinsp;0.059, see above) in unadjusted comparisons of all four infection groups with each other, despite the difference when using pooled values. To reveal whether the inclusion of risk factors as confounders would yield different results, multiple logistic regression analyses were performed. The predictors taken into account included age and sex, CRP, leukocytes, body temperature and blood pressure, and additionally the requirement for oxygen therapy, dyspnoea, fatigue and as comorbidity immunosuppression, in addition to the four types of infections. This choice was based on clinical considerations and the results of the previous analyses (see Tables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e and Supplementary Tables S1, S3).\u003c/p\u003e \u003cp\u003eThe analysis for mortality did still not yield significant associations with the type of infection, however, associations (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 each) with dyspnoea, fatigue, systolic blood pressure, body temperature and CRP emerged. Similarly, ICU admission remained un-associated with the type of infection but there were significant relationships to dyspnoea, systolic blood pressure and CRP (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 each). Thus, even taking into account multiple patient characteristics as confounders, the observed differences in ICU admission rates and mortality were not statistically associated with specific infections.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eTransfer of patients\u003c/h2\u003e \u003cp\u003eDuring the major phase of COVID-19, inter-hospital transfer rates in the RoMed hospitals were high, placing significant stress on the healthcare system [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. To determine whether this persisted, we examined the frequency and underlying reasons for inter-hospital transfers. There were only 16 such transfers attributable to viral infections; 13 transfers occurred from peripheral level 1 care facilities to the level 2 care RoMed Hospital in Rosenheim, of which 5 were due to the requirement for ICU treatment. Additionally, 3 transfers from the level 2 care RoMed Hospital to a Paediatric University Hospital were performed for paediatric intensive care. Compared to the previous data [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] transfer numbers were much lower, and particularly no transfers due to capacity reasons occurred.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eComparison with data from previous seasons\u003c/h2\u003e \u003cp\u003eAs data from three seasons obtained under comparable conditions were available [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], a comparison was possible. The Supplemental Figure \u003cspan refid=\"MOESM2\" class=\"InternalRef\"\u003eS2\u003c/span\u003e shows the total number of infections with SARS-CoV-2, Influenza A/B, or RSV as recorded in the seasons 2022/23, 2023/24 and 2024/25. Influenza B appeared in appreciable numbers, especially in the lower age group only in 2024/25. While Influenza A numbers in adults increased, the proportion and number of both RSV in children and SARS-CoV-2 in adults declined over the three years, particularly when taking into account that the present study involved the largest observation window.\u003c/p\u003e \u003cp\u003eOf further interest was the time course of infections over the past three seasons, to reveal whether their dynamics had changed (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). In 2024/25, SARS-CoV-2 had its peak in September/October 2024 and gradually declined, while in 2023/24 numbers were still high in December and in 2022/23 stayed high until February. In contrast, Influenza A and in particular RSV peaks appeared to have shifted towards the spring months over the three years.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWe also compared mortality in adults between seasons, taking account of the different time windows (Supplemental Table S4). It increased over time for SARS-CoV-2, accompanied by a decrease for Influenza A. In case of RSV, percent mortality was high in 2023/24 but it has to be taken into account that the number was low and thus uncertainty high. When comparing mortality between the three seasons using 3x2 contingency tables for each infection, with or without adjusting the time window, no statistically significant differences were found.\u003c/p\u003e \u003cp\u003eWe also compared the number and proportion of RSV in infants of age less than 1 year. In 2024/25, among 70 infants, 27 (39%) showed RSV infection, in 2023/24 among 157 infants 86 (55%), and in 2022/23 among 145 infants 102 (70%). This showed a decline in the percentage of RSV already prior to the introduction of immunization that occurred in the autumn of 2024 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn the present study, we assessed the prevalence, clinical features and outcomes of patients hospitalized with SARS-CoV-2, Influenza A or B, or RSV infections between August 2024 and April 2025 and compared these findings with data from the previous two seasons. The analysis included patients from all ages admitted to the internal medicine, neurology and paediatrics wards. Compared to the previous two seasons [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], the distribution of infection types slightly changed in 2024/25. SARS-CoV-2 (about 40%) and RSV (about 15%) had become less frequent, and Influenza A more frequent (about 36%). Notable numbers of Influenza B (8%) were detected only in 2024/25. As in the previous two seasons, age distribution showed peaks in young children and older adults, whereby infection-specific age differences persisted; RSV was most prevalent below 18 years of age and SARS-CoV-2 at age\u0026thinsp;\u0026ge;\u0026thinsp;18 years. Cough was most common for Influenza A and RSV, nausea for Influenza B, fatigue for SARS-CoV-2. In adults, ICU admission rates (6\u0026ndash;9%) were similar between SARS-CoV-2, Influenza A/B and RSV, while mortality was highest for SARS-CoV-2 (13.3%) and lowest for Influenza A (6.1%) but without significant difference (p\u0026thinsp;=\u0026thinsp;0.059) when comparing all four infections with each other. Oxygen supplementation, mechanical ventilation and non-invasive ventilation were most frequent for RSV. In patients\u0026thinsp;\u0026lt;\u0026thinsp;18 years of age, no deaths occurred. ICU admission was most frequent for SARS-CoV-2 and oxygen supplementation for RSV, with low absolute numbers. The distribution of infections showed no major differences compared to the two previous seasons, except that Influenza B re-emerged in substantial numbers. In summary, in the season 2024/25, infections with SARS-CoV-2 were still most frequent in adults, and mortality from SARS-CoV-2 tended to be twice as high as for influenza.\u003c/p\u003e \u003cp\u003eWhen comparing the three years, the proportion and number of SARS-CoV-2 infections in adults and of RSV infections in young patients declined over time. In contrast, Influenza A cases increased among adults (see Supplemental Figure \u003cspan refid=\"MOESM2\" class=\"InternalRef\"\u003eS2\u003c/span\u003e). The reductions regarding RSV and SARS-CoV-2 occurred despite the extension of the observation period. Influenza B appeared in notable numbers in 2024/25 for the first time over the past three seasons, and in young patients its number was in the range of Influenza A and SARS-CoV-2. These variations compared to the previous years are in line with data from the Germany national registry [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIt is of great interest to compare the time course of infections between the three years. The 2024/25 season was characterized by SARS-CoV-2 dominance in early autumn (September\u0026ndash;October 2024), followed by peaks of influenza A (January 2025), influenza B (February), and RSV (March) (see Supplemental Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). Therefore, the prolongation of the data collection period ensured the acquisition of the peak month of RSV, as well as the temporal decline in Influenza A and B. Compared to the preceding seasons [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], SARS-CoV-2 frequency decreased earlier, with almost no new cases being detected after January 2025. In contrast, the Influenza A onset occurred later than previously, roughly in coincidence with Influenza B, while RSV activity progressively shifted to a later period of time. These observations (see Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) demonstrate that the temporal dynamics of infections markedly changed from year to year. It is noteworthy that similar shifts of peak occurrences over three consecutive seasons can also be observed in the reports by the Robert Koch institute [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe age distribution was similar to that observed in 2022/23 and 2023/24, showing high numbers in children under 5 years of age and in older individuals, peaking around 85 years of age. Median age was highest in SARS-CoV-2 patients, being 75 years, followed by Influenza A at 72 years. In contrast, RSV and Influenza B predominantly affected younger individuals, with median ages of 2 years and 6 years, respectively. These patterns were consistent with those of the previous two analyses [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] and international findings [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] suggesting that probably the characteristics of the viruses did not markedly change over time.\u003c/p\u003e \u003cp\u003eDespite many similarities, clinical characteristics showed some differences across infections. As previously [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], cough was common with RSV (79%). However, in 2024/25 Influenza A reached the same level (80%). Dyspnea still showed at least a tendency of being most often associated with RSV. These observations are consistent with reports by other investigators [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Fatigue was frequent across all four viral infections but most prevalent for SARS-CoV-2 (88%). This aligns with the 2022/23 data [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] but contrasts with the lower rates of only about 10% in 2023/24 [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] and international studies [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. To which extent such differences are attributable to differences in risk profiles or viral characteristics, cannot be determined from our data. Compared to previous years [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], the pattern of comorbidities and their associations with infection types showed differences. Noteworthy, immunosuppression was the only entity associated with a higher risk of infection across all three seasons. However, different viruses played a role, specifically Influenza B in 2024/25, Influenza A in 2023/24, and RSV in 2022/23.\u003c/p\u003e \u003cp\u003eIn adults, there were no major differences in therapy, although the demand of any oxygen therapy was highest for RSV and least for Influenza B, in concordance with previous data [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e],[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. In line with this, the requirement for mechanical invasive ventilation was highest in RSV, again consistent with the previous findings [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], despite the lack of statistical significance.\u003c/p\u003e \u003cp\u003eMortality in adults was highest for SARS-CoV-2 and RSV and about half as high for Influenza A and B but due to the low numbers of deceased patients, the differences were not statistically significant at least when comparing all four infections with each other (p\u0026thinsp;=\u0026thinsp;0.059). This seems of interest since COVID-19 is frequently regarded as having mortality risk comparable to Influenza, as confirmed by us for 2023/24 [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. It is noteworthy that data from the Robert Koch Institute for the 2024/25 season indicated in-hospital mortality rates of 18 % or SARS-CoV-2 and 17 % or Influenza [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] that are higher than in our study. Therefore, potential perceptions considering SARS-CoV-2 infection as a disease of lower importance, either per se or in comparison to Influenza, might be misguided.\u003c/p\u003e \u003cp\u003eMortality was not markedly dependent on the length of the time window chosen for analysis (see Supplemental Table \u003cspan refid=\"MOESM2\" class=\"InternalRef\"\u003eS2\u003c/span\u003e). The comparison with previous seasons (Supplemental Table S4) indicated that mortality from SARS-CoV-2 even increased over time, while that from Influenza A decreased. In case of RSV, it has to be taken into account that numbers were low and thus uncertainty was high. When varying observation windows, there were also no marked changes regarding ICU admission rate (Supplemental Table \u003cspan refid=\"MOESM2\" class=\"InternalRef\"\u003eS2\u003c/span\u003e). However, admission rates in 2024/25 were about half the rates of the previous two seasons or even lower [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Our findings are in line with a large Spanish study conducted between 2021 and 2024, which was, however, limited to people aged\u0026thinsp;\u0026ge;\u0026thinsp;65 years [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Taken together, they suggest annual changes in mortality and ICU admission rate, which were, however, of the magnitude of previously known variations. The present observations do not allow to decide to which extent there might have been associations with virus variants or protective measures such as the recently established RSV vaccination for older or comorbid patients in Germany.\u003c/p\u003e \u003cp\u003eTo identify virus-specific risk factors for ICU admission or mortality in the presence of a complex pattern of potential confounders, multiple logistic regression analyses were employed, however, they did not reveal such risk factors. This suggests that with a multiplicity of infections, virus-specific risk factors become more difficult to identify compared to the more homogeneous COVID-19 situation, in which strong risk factors such as renal function could be clearly identified [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWe considered it important to cover the whole spectrum of patients\u0026rsquo; ages and therefore included children into our analysis. As in the previous two seasons [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], no deaths occurred in this group and the absolute number and rate of ICU admissions was low, without significant differences between infections. ICU admission due to RSV tended to become less frequent but the need for oxygen supplementation remained highest for RSV, in line with other data [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Compared to a Hungarian study [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], however, the rate of oxygen supplementation was much higher in our cohort. Irrespective of these differences, our findings confirm that in young patients RSV has re-appeared in notable numbers, while in 2020 to early 2022 clearly SARS-CoV-2 was dominant [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. It also seems noteworthy that the peak of RSV incidence showed a steady shift in time from December in 2022 to March in 2025 (see Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and Supplemental Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSince autumn 2024, RSV immunization in Germany includes vaccination for adults aged\u0026thinsp;\u0026ge;\u0026thinsp;75 years and at-risk individuals aged\u0026thinsp;\u0026ge;\u0026thinsp;60 years, as well as maternal vaccination and monoclonal antibody prophylaxis for infants [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Based on this, RSV-associated morbidity may be reduced in infants and older adults [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. We did not have complete documentation regarding vaccination against RSV, SARS-CoV-2 and Influenza in adults, in contrast to RSV immunization in infants introduced in the autumn of 2024. When comparing the percentages of RSV immunization with RSV versus non-RSV infections, the analysis did not point towards detectable effects of immunization. This does not invalidate the effect of immunization in infants, as the analysis might have occurred too early to detect relevant effects. On the other hand, compared to our previous data [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], the number of hospitalized infants (age\u0026thinsp;\u0026lt;\u0026thinsp;1 year) with RSV infection declined from 102 and 86 to only 27 cases in 2022/23, 2023/24 and 2024/25, respectively, in line with reductions observed in recent analyses of German Registry data [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. These analyses also indicated no major changes of RSV infection frequencies in children of age 1 year and older, again in line with our data, as we observed 44, 67, and 37 hospitalized children of age 1\u0026ndash;3 years in the three consecutive seasons. Taken together, these observations might be considered as indicating the effectiveness of immunization in infants.\u003c/p\u003e \u003cp\u003eA great concern in the COVID-19 pandemic was the stress on the health-care system as reflected in a high rate of inter-hospital transfers, as demonstrated in a previous study [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. In the season 2024/25, however, only 16 inter-hospital transfers linked to respiratory viral infections occurred, and no signs of capacity problems requiring transfer were observed. This suggests a return to usual conditions regarding the stress on the health-care system after waning of the COVID-19 pandemic.\u003c/p\u003e \u003cp\u003eA key strength is the comparability of data over three consecutive seasons using identical methodology in a single center, while including all age groups and multiple respiratory viruses. All data came from the same primary care hospital, ensuring that patients\u0026rsquo; population, medical staff, diagnostic standards and treatment were similar. Compared to the previous two years [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], we extended the data collection period to cover the entire season of infections [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. By accounting for the different time periods, comparisons regarding the number, mortality and course of infections could be adjusted.\u003c/p\u003e \u003cp\u003eOn the other hand, the fact that this investigation was monocentric may limit the generalisability of its findings. Information on vaccination status in adults was not available in a consistent and complete manner. In paediatric patients, symptoms were only documented through third parties, which we deemed as unsuitable for analysis. In a number of paediatric cases, no blood samples were obtained, thus laboratory data were only analyzed in adults. Finally, we had to rely on diagnoses extracted from discharge letters based on ICD-10 coding, in which misclassification due to coding errors cannot be entirely excluded, although it is unlikely.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe comparison of hospitalizations due to infections with SARS-CoV-2, Influenza A/B, or RSV during the season 2024/25 with the previous two seasons showed that the proportion of SARS-CoV-2 had declined but remained high at 40%. Absolute and relative numbers of RSV infections had decreased in adults as well as young patients including infants. Remarkably, the peak incidence of RSV shifted from December 2022 to March 2025. Moreover, Influenza B re-appeared in significant numbers, particularly in younger patients. SARS-CoV-2, followed by RSV, showed the highest mortality in adults, while that for Influenza was half as high. None of the young patients died. The need for oxygen supplementation was highest with RSV infection. The results not only underline the occurrence and clinical relevance of known respiratory viral infections but also emphasize the ongoing burden from SARS-CoV-2, with variations but no systematic changes of frequency and mortality over three consecutive years.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eBMI\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Body Mass Index\u003c/p\u003e\n\u003cp\u003eCAD\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Coronary artery disease\u003c/p\u003e\n\u003cp\u003eCKD\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Chronic kidney disease\u003c/p\u003e\n\u003cp\u003eCOPD\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Chronic obstructive pulmonary disease\u003c/p\u003e\n\u003cp\u003eCRP \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;C-reactive protein\u003c/p\u003e\n\u003cp\u003eeGFR\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Estimated glomerular filtration rate\u003c/p\u003e\n\u003cp\u003eICU\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Intensive Care Unit\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLTOT\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Long-term oxygen therapy\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMIV\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Invasive mechanical ventilation\u003c/p\u003e\n\u003cp\u003en.d. \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;not determined\u003c/p\u003e\n\u003cp\u003eNIV \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Non-invasive ventilation\u003c/p\u003e\n\u003cp\u003ePAD\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Peripheral arterial disease\u003c/p\u003e\n\u003cp\u003epCO\u003csub\u003e2\u003c/sub\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Arterial pressure of carbon dioxide\u003c/p\u003e\n\u003cp\u003ePCR\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Polymerase Chain Reaction\u003c/p\u003e\n\u003cp\u003epO\u003csub\u003e2\u003c/sub\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Arterial pressures of oxygen\u003c/p\u003e\n\u003cp\u003eRSV\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Respiratory Syncytial Virus\u003c/p\u003e\n\u003cp\u003eSpO\u003csub\u003e2\u003c/sub\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Peripheral oxygen saturation\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003cbr\u003e\u003c/strong\u003eApproval for this retrospective study was obtained from the Ethics Committee of the University Hospital of Regensburg (Number 25-4131-104) which served as an Institutional Review Board. Moreover, the study was in full accordance with the Declaration of Helsinki. According to the Institutional Review Board, there was no need for patients\u0026rsquo; consent to participate in this retrospective analysis of anonymized data. Clinical trial number: not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003cbr\u003e\u003c/strong\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data set is owned by the authors and not publicly available. It can be shared only by agreement with the authors and consent of the Institutional Review Board (Ethics Committee of the University Hospital of Regensburg).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;The authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003cbr\u003e\u003c/strong\u003eThe study was performed by available resources without specific funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003cbr\u003e\u003c/strong\u003eB.T.: Writing and revision of the manuscript, data collection, quality control and analysis; R.A.J.: Writing and revision of the manuscript, data analysis; S.E.: Revision of the manuscript, support in data acquisition; P.A.: Revision of the manuscript, interpretation of the data; K.K.: Revision of the manuscript, interpretation of the data; S.B.: Writing and revision of the manuscript, design of the study, interpretation of the data.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003cbr\u003e\u003c/strong\u003eWe would like to thank the administration of the RoMed Hospital for their support in the data collection from the files.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; details including first names\u003cbr\u003e\u003c/strong\u003eBenno Trautwein (B.T.)\u003csup\u003e1\u003c/sup\u003e\u003cbr\u003eRudolf A. J\u0026ouml;rres (R.A.J.)\u003csup\u003e2\u003c/sup\u003e\u003cbr\u003eSebastian Engelhardt (S.E.)\u003csup\u003e1\u003c/sup\u003e\u003cbr\u003ePeter Alter (P.A.)\u003csup\u003e3\u003c/sup\u003e\u003cbr\u003eKathrin Kahnert (K.K.)\u003csup\u003e4,5\u003c/sup\u003e\u003cbr\u003eStephan Budweiser (S.B.)\u003csup\u003e1,6\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e1\u003c/sup\u003eDepartment of Internal Medicine III, Division of Pneumology and Respiratory Medicine, RoMed Hospital Rosenheim, Ellmaierstra\u0026szlig;e 23, 83022 Rosenheim, Germany\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e2\u003c/sup\u003eInstitute and Outpatient Clinic for Occupational, Social and Environmental Medicine, LMU Hospital, Comprehensive Pneumology Center Munich (CPC-M), Member of the German Center for Lung Research (DZL), Ziemssenstra\u0026szlig;e 1, 80336 Munich, Germany\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e3\u003c/sup\u003eDepartment of Medicine, Pulmonary and Critical Care Medicine, University of Marburg (UMR), Germany, Member of the German Center for Lung Research (DZL), Baldingerstra\u0026szlig;e, 35043 Marburg, Germany\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e4\u003c/sup\u003eMediCenterGermering, Hartstra\u0026szlig;e 53, 82110 Germering\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e5\u003c/sup\u003eDepartment of Medicine V, LMU University Hospital, LMU Munich, Comprehensive Pneumology Center Munich (CPC-M), German Center for Lung Research (DZL), Marchioninstra\u0026szlig;e 15, 81377 M\u0026uuml;nchen, Germany\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e6\u003c/sup\u003eDepartment of Internal Medicine II, University Hospital Regensburg, 93053 Regensburg, Germany\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eHanage WP, Schaffner W. Burden of Acute Respiratory Infections Caused by Influenza Virus, Respiratory Syncytial Virus, and SARS-CoV-2 with Consideration of Older Adults: A Narrative Review. Infect Dis Ther. Jan. 2025;14:5\u0026ndash;37. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40121-024-01080-4\u003c/span\u003e\u003cspan address=\"10.1007/s40121-024-01080-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFeldman C, Anderson R. RSV: an overview of infection in adults. Pneumonia. Jun. 2025;17(1):15. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s41479-025-00165-z\u003c/span\u003e\u003cspan address=\"10.1186/s41479-025-00165-z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWiechert L, et al. Characteristics and outcomes of patients hospitalized for infection with Influenza A, SARS-CoV-2 or respiratory syncytial virus in the season 2023/2024 in a large German primary care centre. Eur J Med Res. Oct. 2024;29(1):509. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s40001-024-02096-9\u003c/span\u003e\u003cspan address=\"10.1186/s40001-024-02096-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQuarg C, J\u0026ouml;rres RA, Engelhardt S, Alter P, Budweiser S. Characteristics and outcomes of patients hospitalized for infection with influenza, SARS-CoV-2 or respiratory syncytial virus in the season 2022/2023 in a large German primary care centre. Eur J Med Res. Dec. 2023;28(1). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s40001-023-01482-z\u003c/span\u003e\u003cspan address=\"10.1186/s40001-023-01482-z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTolksdorf K, et al. Robert Koch-Institut: ARE-Wochenbericht KW 15/2025. Apr. 2025. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.25646/13099\u003c/span\u003e\u003cspan address=\"10.25646/13099\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTolksdorf K, et al. Robert Koch-Institut: ARE-Wochenbericht KW 14/2025. Apr. 2025. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.25646/13091\u003c/span\u003e\u003cspan address=\"10.25646/13091\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eInsitute RK. Schutzimpfung und Immunisierung gegen Respiratorische Synzytial-Viren (RSV).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHeiland LM, et al. Retrospektive klinisch-kausale Bewertung einer positiven PCR f\u0026uuml;r SARS-CoV-2 bei hospitalisierten Patienten des gesamten Altersspektrums in einem Krankenhaus der Schwerpunktversorgung. Pneumologie. Feb. 2024;78(02):100\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1055/a-2161-5866\u003c/span\u003e\u003cspan address=\"10.1055/a-2161-5866\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSuski P, et al. Period of hospitalization and mortality in transferred versus non-transferred COVID-19 patients: results from Germany. Sci Rep. Dec. 2024;14(1). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41598-024-57272-y\u003c/span\u003e\u003cspan address=\"10.1038/s41598-024-57272-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStaat D, Tolksdorf K, Schuler E. Krankheitslast von schweren akuten Atemwegserkrankungen (SARI) in der Saison 2024/25 im station\u0026auml;ren Bereich, 2025. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.25646/13338\u003c/span\u003e\u003cspan address=\"10.25646/13338\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBuda S et al. Robert Koch-Institut: ARE-Wochenbericht KW 23/2023, 2023. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.25646/11535\u003c/span\u003e\u003cspan address=\"10.25646/11535\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBuda S et al. Robert Koch-Institut: ARE-Wochenbericht KW 23/2024, 2024. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.25646/12144\u003c/span\u003e\u003cspan address=\"10.25646/12144\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTolksdorf K et al. Robert Koch-Institut: ARE-Monatsbericht KW 21\u0026ndash;23/2025, 2025. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.25646/13175\u003c/span\u003e\u003cspan address=\"10.25646/13175\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKorsun N, et al. Resurgence of respiratory syncytial virus with dominance of RSV-B during the 2022\u0026ndash;2023 season. Front Microbiol. Apr. 2024;15. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fmicb.2024.1376389\u003c/span\u003e\u003cspan address=\"10.3389/fmicb.2024.1376389\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChauvel C, et al. Community and Hospital-Based Laboratory Surveillance for Influenza, Respiratory Syncytial Virus, and SARS-CoV-2 During the 2023\u0026ndash;2024 Season, Lyon, France. J Med Virol. Sep. 2025;97(9):e70549. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/jmv.70549\u003c/span\u003e\u003cspan address=\"10.1002/jmv.70549\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHaeberer M, et al. RSV Risk Profile in Hospitalized Adults and Comparison with Influenza and COVID-19 Controls in Valladolid, Spain, 2010\u0026ndash;2022. Infect Dis Ther. Sep. 2024;13(9):1983\u0026ndash;99. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40121-024-01021-1\u003c/span\u003e\u003cspan address=\"10.1007/s40121-024-01021-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSurie D, et al. Severity of Respiratory Syncytial Virus vs COVID-19 and Influenza Among Hospitalized US Adults. JAMA Netw Open. Apr. 2024;7(4):e244954. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1001/jamanetworkopen.2024.4954\u003c/span\u003e\u003cspan address=\"10.1001/jamanetworkopen.2024.4954\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eClausen CL, et al. Clinical Manifestations and Outcomes in Adults Hospitalized With Respiratory Syncytial Virus and Influenza a/B: A Multicenter Observational Cohort Study. Open Forum Infect Dis. Sep. 2024;11(10). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1093/ofid/ofae513\u003c/span\u003e\u003cspan address=\"10.1093/ofid/ofae513\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVega-Piris L, et al. Severity of respiratory syncytial virus compared with SARS-CoV-2 and influenza among hospitalised adults\u0026thinsp;\u0026ge;\u0026thinsp;65 years. J Infect. Nov. 2024;89(5):106292. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jinf.2024.106292\u003c/span\u003e\u003cspan address=\"10.1016/j.jinf.2024.106292\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKurzeder L et al. Oct., A simple risk score for mortality including the PCR Ct value upon admission in patients hospitalized due to COVID-19., \u003cem\u003eInfection\u003c/em\u003e, vol. 50, no. 5, pp. 1155\u0026ndash;1163, 2022, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s15010-022-01783-1\u003c/span\u003e\u003cspan address=\"10.1007/s15010-022-01783-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBudweiser S, et al. Patients\u0026rsquo; treatment limitations as predictive factor for mortality in COVID-19: results from hospitalized patients of a hotspot region for SARS-CoV-2 infections. Respir Res. Jun. 2021;22(1):168. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12931-021-01756-2\u003c/span\u003e\u003cspan address=\"10.1186/s12931-021-01756-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eK. M. Andersen et al., Clinical Outcomes in Children \u0026lt;5 Years of Age Hospitalized for Respiratory Syncytial Virus, COVID-19 or Influenza in the United States, \u003cem\u003ePediatric Infectious Disease Journal\u003c/em\u003e, May 2025, doi: 10.1097/INF.0000000000004866.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKurz H, et al. Respiratory Syncytial Virus and Influenza During the COVID-19 Pandemic: A Two-center Experience. Pediatr Infect Dis J. May 2024;43(5):410\u0026ndash;4. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/INF.0000000000004260\u003c/span\u003e\u003cspan address=\"10.1097/INF.0000000000004260\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKurz H, Hoffmann H, Oeser R, Resch B. Burden of disease and seasonal data of children hospitalized due to RSV and Influenza infection before, during and after the COVID-19 pandemic. Eur J Pediatr. Jun. 2025;184(7):459. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00431-025-06289-0\u003c/span\u003e\u003cspan address=\"10.1007/s00431-025-06289-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOrosz N, G\u0026ouml;m\u0026ouml;ri G, Battamir U, Nagy AC. Hospital-based cross-sectional study on the clinical characteristics of children with severe acute respiratory infections in Hungary. BMC Infect Dis. Nov. 2024;24(1):1268. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12879-024-10186-6\u003c/span\u003e\u003cspan address=\"10.1186/s12879-024-10186-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKrauer F, et al. Effectiveness and efficiency of immunisation strategies to prevent RSV among infants and older adults in Germany: a modelling study. BMC Med. Oct. 2024;22(1):478. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12916-024-03687-3\u003c/span\u003e\u003cspan address=\"10.1186/s12916-024-03687-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSch\u0026ouml;nfeld V, Rau C, Cai W, Wichmann O, Harder T. The incidence of RSV infection since the introduction of monoclonal antibody prophylaxis. Dtsch Arztebl Int Aug. 2025. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3238/arztebl.m2025.0111\u003c/span\u003e\u003cspan address=\"10.3238/arztebl.m2025.0111\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAcknowledgements We would. like to thank the administration of the RoMed Hospital for their support in data collection from the files.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAuthors' contributions BT. Writing and revision of the manuscript, data collection, quality control and analysis; RAJ: Writing and revision of the manuscript, data analysis; SE: Revision of the manuscript, support in data acquisition; PA: Revision of the manuscript, interpretation of the data; KK: Revision of the manuscript, interpretation of the data; SB: Writing and revision of the manuscript, design of the study, interpretation of the data.\u003c/span\u003e\u003c/li\u003e \u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-infectious-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"infd","sideBox":"Learn more about [BMC Infectious Diseases](http://bmcinfectdis.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/infd","title":"BMC Infectious Diseases","twitterHandle":"#bmcinfectdis","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8402845/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8402845/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eRespiratory viruses including influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 continue to cause morbidity and mortality, particularly in older adults and young children. We aimed to assess their clinical impact and outcomes in the 2024/25 season in comparison with the past two seasons, using data from the same primary care hospital in Southern Germany.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eRetrospective analysis of patients hospitalized with PCR-confirmed SARS-CoV-2, Influenza A/B, or RSV infection between August 2024 and April 2025 in the internal, neurological and paediatric departments. Clinical characteristics including comorbidities, symptoms, laboratory parameters and outcomes were analyzed, with focus on the need/type of respiratory support, admission to intensive care, and death.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOf 723 patients included, 714 had mono infections with SARS-CoV-2 (40.0%), influenza A (35.7%) or B (8.2%), or RSV (14.8%), with high frequency in young children and older adults. Among patients\u0026thinsp;\u0026ge;\u0026thinsp;18 years of age (n\u0026thinsp;=\u0026thinsp;514, 48.3% SARS-CoV-2, 41.3% Influenza A, 3.1% Influenza B, 6.6% RSV), admission to the intensive care unit (ICU) was required in 42 patients (8.1% SARS-CoV-2, 8.5% Influenza A, 6.3% Influenza B, 8.8% RSV), and 51 patients died (13.3% of SARS-CoV-2, 6.1% Influenza A, 6.3% Influenza B, 11.8% RSV). The highest demand for oxygen therapy and mechanical invasive ventilation occurred with RSV. Among patients\u0026thinsp;\u0026lt;\u0026thinsp;18 years of age (n\u0026thinsp;=\u0026thinsp;209, 19.6% SARS-CoV-2, 22.0% Influenza A, 21.1% Influenza B, 34.9% RSV), 5 were admitted to the ICU (4.8% of SARS-CoV-2, 0.0% Influenza A, 4.5% Influenza B, 1.5% RSV), and none died. Compared to the two preceding seasons, there were variations but no statistically significant changes in prevalence and outcome. Mortality in adults tended to increase for SARS-CoV-2 and decrease for RSV. Moreover, Influenza A and RSV activity shifted toward later months, and Influenza B emerged prominently only in 2024/25.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eDuring the 2024/25 season, the distribution of viral respiratory tract infections showed no major differences compared to the two previous seasons; however, Influenza B re-emerged in substantial numbers. Overall, infections with SARS-CoV-2 were still most frequent, and in adult patients mortality tended to be twice as high as in patients with influenza.\u003c/p\u003e","manuscriptTitle":"Clinical course of hospitalizations with Influenza, SARS-CoV-2 and respiratory syncytial virus (RSV) infections in the season 2024/2025 in a large German primary care centre and comparison with the previous two years","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-09 06:37:32","doi":"10.21203/rs.3.rs-8402845/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-13T06:14:58+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-10T12:44:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"228103426672387761017910373988787336517","date":"2026-04-02T10:35:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"255939913746389408690954491820362836409","date":"2026-03-09T08:51:54+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-03T11:49:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"202667300925249886057706777104738711684","date":"2026-02-09T15:01:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"42096059449040942350835300451286355370","date":"2026-01-08T13:24:17+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-06T13:03:23+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-26T06:04:22+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-22T23:47:14+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-22T23:45:57+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Infectious Diseases","date":"2025-12-19T08:46:43+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-infectious-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"infd","sideBox":"Learn more about [BMC Infectious Diseases](http://bmcinfectdis.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/infd","title":"BMC Infectious Diseases","twitterHandle":"#bmcinfectdis","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"14f12d19-4302-430a-9056-91dbbe08ac4f","owner":[],"postedDate":"January 9th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-03T14:23:11+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-09 06:37:32","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8402845","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8402845","identity":"rs-8402845","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}