Burden, Risk Factors, and Outcomes of RSV Infection in Pediatric ICUs Across Türkiye: RSVP Study

Burden, Risk Factors, and Outcomes of RSV Infection in Pediatric ICUs Across Türkiye: RSVP Study | 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 Burden, Risk Factors, and Outcomes of RSV Infection in Pediatric ICUs Across Türkiye: RSVP Study Yasemin Coban, Gultac Evren, Dincer Yildizdas, Neslihan Zengin, and 40 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7691297/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Respiratory syncytial virus (RSV) is one of the leading causes of requiring a pediatric intensive care unit (PICU). This study aimed to characterize the clinical features, complications, co-infections, and risk factors associated with RSV-related morbidity and mortality in a large PICU cohort over five years. Methods This is a retrospective multicenter study to evaluate patients with RSV infection admitted to the PICUs in Türkiye between 2020 and 2024, including the COVID-19 pandemic. Results Medical records of 646 children (360 boys, 286 girls, 70% younger than 12 months; 70.6% previously healthy) have been evaluated. Underlying disease was identified in 190 children (29.4%), and congenital heart disease in 58 (9%). Complications included pleural effusion (n = 8), pneumothorax (n = 8), central nervous system involvement (n = 19), apnea (n = 10), and myocarditis (n = 5). Respiratory co-pathogens were detected in 169 patients (26.2%). During PICU admission, 165 patients (25.5%) required IMV. The mortality rate was 5.4% due to RSV infection. Logistic regression revealed that the presence of an underlying disease significantly increased mortality risk (OR 3.15, p < 0.01) and this association remained significant in infants under one year (OR 3.57, p < 0.01). Conclusion Most children admitted to the PICU due to RSV infection were under one year of age and previously healthy, while mortality was associated with underlying conditions. Monitoring RSV cases in the PICU can be used as a probe for determining the burden of disease and economic cost in the country and for potential treatment and prevention strategies. respiratory syncytial virus RSV pARDS Figures Figure 1 Figure 2 1. INTRODUCTION Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory infections and associated hospitalizations in infants and children globally. 1 In 2019, there were 33 million RSV-associated cases of acute lower respiratory airway infection, 3.6 million RSV-associated hospital admissions, and 101,400 RSV-attributable deaths in children under 5 years of age. 2 Initial RSV infection often occurs in the first year of life, with almost all children infected by their second birthday . 3 More than 97% of pediatric RSV-related deaths occurred in low- and middle-income countries. 1 In Türkiye, there is limited data available for RSV hospitalization and PICU requirements, representing the whole country. To understand the full clinical impact of potential RSV prevention, insight into the yet unseen burden of severe RSV disease will be helpful. The aim of this study was to evaluate the distribution of age and risk factors among patients admitted to the pediatric intensive care unit due to RSV from 2020 to 2024 and define the clinical course in the PICU. 2. PATIENTS AND METHOD 2.1. Study Design and Setting: This study is a retrospective, multicenter cohort analysis conducted in PICUs across Türkiye. Data were collected from children diagnosed with laboratory-confirmed RSV infection who were admitted to participating PICUs between January 1, 2020, and December 31, 2024 . The study included data from multiple tertiary hospitals located in various regions of Türkiye. This retrospective study was conducted in accordance with the Declaration of Helsinki (1964 and its later amendments). The study was approved by the Local Ethical Committee of the Mugla Sıtkı Kocman University Faculty of Medicine on 13.01.2025, decision number 5. Following authorization from the local ethical committee, we collected medical records of patients diagnosed with RSV from 23 centers in 14 different cities. Human Ethics and Participation Consent statements: not applicable’ as it is retrospective. 2.2. Patient Selection Patients were eligible for inclusion if they met the following criteria: · Age between 1 month and 18 years at the time of PICU admission. · Confirmed RSV infection via polymerase chain reaction (PCR) · Admitted to a participating PICU during the study period. Patients hospitalized in the newborn intensive care unit have not been evaluated. Cases with incomplete medical records or uncertain RSV diagnoses were also excluded. 2.3. Data Collection Data were obtained from electronic and paper-based medical records. Extracted variables included: demographics (age, sex, birth history, and neonatal intensive care unit (NICU) admission history, p rematurity was defined as 37 weeks), clinical history (presence of prematurity, congenital heart disease, chronic respiratory or neurological conditions, genetic syndromes (e.g., Down syndrome), or other underlying illnesses. · RSV-related diagnosis : bronchiolitis, pneumonia, pediatric acute respiratory distress syndrome (pARDS) and complications such as pleural effusion, pneumothorax, apnea, myocarditis, and seizures. · Treatment modalities : type of respiratory support. · Outcomes : PICU length of stay, total hospital stay, and in-hospital mortality. 2.4. Outcomes Primary outcome - Distribution of age and risk factors among patients admitted to the pediatric intensive care unit due to RSV from 2020 to 2024. Secondary outcomes - Characteristics of patients who develop pARDS, comparison of patients who develop pARDS and those who do not develop - Determining the characteristics of patients death due to RSV infection and comparing them with surviving patients - The early period of the pandemic, the easing restrictions period, and the evaluation of changes in the number of RSV infection cases and seasonality after the pandemic 2.5. Statistical analysis Statistical analysis was performed using the JASP statistical program. 3. RESULTS The study included 646 children (360 boys, 286 girls) admitted to intensive care units with RSV infection between January 1, 2020, and December 31,2024. Patient ages ranged from 1 to 214 months (median: 5 months). Of these, 149 were aged 1-2 months, 358 were younger than 6 months, and 465 were younger than 1 year. In total, 492 cases were under 2 years and 577 were under 5 years. Seventy patients were between 6 and 18 years of age (Figure 1). The distribution of cases was 73 in 2020, 48 in 2021, 130 in 2022, 227 in 2023, and 168 in 2024. In Türkiye, the first COVID-19 patient detected in March 2020, and restriction policies started at this date. There are limited cases that have been seen from March 2020 to September 2022. Since September 2022, in 2022-2023 and 2024, resurgences of RSV infection have been noted, peaking at November to January (Figure 2). Of the cases, 388 were delivered via C-section, while 258 were delivered vaginally. Of the cases, 139 were preterm (21.5%), whereas 507 were term births (78.5%). The gestational week in cases with a history of premature birth was 32.9 ± 2.96 weeks (ranging from 23 to 36 weeks). A total of 174 cases (26.9%) were previously monitored in the neonatal intensive care unit. In 190 instances (29.4%), a history of underlying disease was noted, while 58 instances involved congenital heart disease (Table 1). None of the patients received palivizumab prophylaxis. Table 1. Presence of underlying condition in patients with RSV infection in PICU. Underlying Condition Congenital Heart Disease Type N=58 VSD 12 ASD 13 ASD/VSD 9 PDA 7 ASD/VSD/PDA 2 Aortic Coarctation 2 TOF (Tetralogy of Fallot) 3 VSD + PDA 1 ASD + PS (Pulmonary Stenosis) 1 Bicuspid Aortic Valve 1 Cardiomyopathy 1 Double Aortic Arch 1 ASD + VSD + Aortic Coarctation 1 ASD + PDA 1 Transposition of great arteries 1 Epilepsy / Epileptic Syndrome 22 Cerebral Palsy with Epilepsy 21 Bronchopulmonary Dysplasia (BPD) 20 Down Syndrome 15 Hematologic / Oncologic Disease 12 Genetic Syndromes 12 Neuromotor Retardation 10 Immunodeficiency 8 Spinal Muscular Atrophy (SMA) 7 Asthma 6 Metabolic Disease 6 Allergic Disorders 4 Diabetes Mellitus 3 Esophageal Atresia 3 Chronic Lung Disease/Cystic fibrosis 4 Congenital Infection 2 Cleft Lip and Palate 1 Osteogenesis Imperfecta 1 Congenital Muscular Dystrophy 1 Other 19 Congenital heart disease have been isolated cardiac defects of associated with other underling disorders Of the 646 cases, 246 (38.1%) were hospitalized for bronchiolitis, 386 (59.8%) for pneumonia, and 14 for other reasons. Complications included pleural effusion ( n=8), pneumothorax (n=8), central nervous system findings and convulsions (n=19), apnea (n=10) and myocarditis (n=5). pARDS was established in 82 cases (12.7%) and 2 required ECMO. Overall, 35 patients died (mortality: 5.4%). The median length of stay in PICU was 6 days (range: 1-155 days), and median hospital stay was 9 days (range: 1-155 days). On PICU admission, 102 patients received oxygen therapy, 381 patients received HFNC, 57 patients received NIV-ST, and 106 patients required invasive mechanical ventilation. During the follow-up, 377 required HFNC, 96 required NIV-ST, and 165 (25.5%) required invasive mechanical ventilation. RSV co-infections were identified in 169 patients. The most frequent were rhinovirus/enterovirus (n=57), influenza A (n=23), coronaviruses N63/OC43/HKU (n= 17), adenovirus (n=15), SARS-CoV-2 (n=12). Less common agents included parainfluenza, bocavirus, parechovirus, and multi-virus combinations (Supplementary Table 1). These findings underscore the clinical impact of viral co-infections in RSV cases. A total of 82 patients were diagnosed with pARDS ( 32 girls, 50 boys; median age: 6 months, range: 1-151 months). Cases occurred most frequently in December (n=30) and January (n=24). Cesarean delivery was reported in 62.2 %, incuding 20 preterm and 62 term births. Underlying diseases were present in 39 patients (47.6%), including 16 with congenital heart disease. Overall, 56 had mild/moderate and 26 severe pARDS. Eight patients died, yielding a mortality rate of 9.8%. Secondary infections were identified in 49 RSV cases. The most common pathogens were Streptococcus pneumoniae and Pseudomonas aeruginosa (10 cases each), followed by Haemophilus influenzae (7) and Staphylococcus aureus (5). Less frequent pathogens included Klebsiella pneumoniae, Acinetobacter spp., Candida spp ., and various other bacteria, such as Stenotrophomonas maltophilia, Streptococcus pyogenes, and E. coli (Supplementary Table 2). Only the presence of underlying disease (OR 3.149; 0.787-3.383, p<0.01). When we checked below one year of age, again only the presence of underlying disease (OR 3.567; p<0.01). Among the 35 deceased patients, 15 were male and 20 were female. Twenty-one cases were delivered via cesarean section, while fourteen cases were delivered vaginally. Ten cases were classified as premature, while twenty-five cases were categorized as term. Thirteen cases exhibited a history of admission to the neonatal intensive care unit. Among the deceased cases, 27 exhibited a history of underlying disease, while 5 cases involved congenital heart disease. The mortality risk in patients with underlying diseases was significantly higher than in those without such conditions (OR 2.22; 95% CI 1.38-3.17; p< .001). 4. DISCUSSION This is one of the largest clinical studies, including 646 children with RSV in PICUs across Türkiye. In the present study, 76.1% of the patients are below two years of age, 72% are below one year of age, and 55.4% were below 6 months of age. 23% of the patients are 1–2 months of age, and this age period is the peak of PICU stay. In our PICU cohort, 21.5% were preterm births, 8.7% had congenital heart disease, and 70.6% were previously healthy. Our findings are consistent with global patterns, particularly the high burden among infants < 12 months. Halasa et al. 4 showed that 65% of children requiring PICU stay are below 1 year of age, 5–10% have congenital heart disease, and 20% were prematurely born in the US. Another study from United States showed that 63% of patients were below 1 year old, 8% had congenital heart disease, 15–20% were preterm. 5 Regarding the Brick Study, a nationwide, prospective, observational, multicenter study which was performed in the Netherlands, of 423 patients, median age was 46 days, 72.9% were term born and 69% had no comorbidities. 6 Young age (< 6 months) is an independent risk factor even without comorbidities. 7 In our study neurological disorders are important underlying conditions for RSV infection requiring PICU. BPD and other chronic pulmonary disorders, Down syndrome, and immune deficiencies are important risk factors. The presence of underlying disorders 3-fold increased the pARDS and also 2.2-fold increased the mortality. A study analyzing data from England estimated RSV hospitalization rates in infants up to 24 months old, highlighting higher rates among those with risk factors such as chronic lung disease and congenital heart disease. 8 While underlying disorders are important for the severity and mortality of the disease, 70.6% of children with RSV who required PICU stays were previously healthy. Preventive strategies are essential for healthy infants as well as infants with underlying disorders. No specific treatment exists for RSV disease. Infants with RSV disease require supportive treatment. 1 In our study, on PICU admission, 58.9% of patients received HFNC, 8.8% of patients NIV-ST, and 16.5% of patients required invasive mechanical ventilation. During the follow-up, patients required invasive mechanical ventilation. Increased to 25.5%. Previous studies showed different invasive mechanical ventilation requirements, varying from 24% to 61.1% 4–5 . Among children hospitalized with RSV, approximately 29.7% required positive pressure ventilation, and 22.3% required invasive mechanical ventilation in the United States. 5 The development of ARDS in children with RSV infection is less common but can occur, particularly in severe cases 9 . In our cohort of 82 cases diagnosed with pARDS, the median age was 6 months. Among these cases, 24.4% were premature, 47.6% had underlying conditions, and 19.5% had congenital cardiac disease. 64.6% of pARDS cases are moderate or severe, and the mortality rate was 9.8%. A study reported that among children under 2 years admitted to the PICU with RSV infection, the incidence of ARDS was approximately 20%, with 7% classified as severe pARDS. 10 Another study observed that 15.9% of children with RSV infection developed ARDS. 11 An earlier study reported a 15.9% incidence of ARDS in children with RSV infection in the Netherlands. 12 The variability in PICU admission rates, mechanical ventilation requirements, and ARDS incidence highlights the need for continued surveillance and targeted preventive strategies. In addition to severe respiratory distress, different acid-base disorders including respiratory or metabolic acidosis, and need for high oxygen supplementation, co- or superinfection have an increased risk of complications and PICU need. 13 In this cohort, the most common co-infection was rhinovirus/enterovirus, followed by influenza A, coronaviruses NL63, OC43, and HKU, adenovirus, and SARS-CoV-2. These findings highlight the significant role of respiratory viral co-infections in children with RSV, which may complicate clinical management and outcomes. In our study, 7.6% of children were complicated with bacterial and Candida infections, mainly Streptococcus pneumoniae and Pseudomonas aeruginosa . This spectrum indicates that there must be vigilance regarding bacterial and fungal superinfections in children with RSV, which may impact disease severity and management. Some studies suggest higher viral loads correlate with more severe disease 13 ; however, we did not perform analysis for viral loads. Prevention strategies against viral, bacterial, and fungal diseases (influenza and pneumococcal conjugated vaccine and infection prevention strategies bundles in PICU) are essential. In our study the mortality rate was 5.4%, mostly with comorbidities. A systematic review of severe RSV cases reported a case fatality range of 1.9% to 5.9% in hospitalized pediatric patients. 14 In our study, 2023, 203 children were admitted to PICUs in participating centers due to RSV infection, with 160 of these children under the age of 1 year (excluding those under 1 month). These centers represent approximately 15% of the total PICU beds in Turkiye. Extrapolating from this data, the estimated total number of RSV-related PICU admissions nationwide would be approximately 1,353 cases, and of these, approximately 1,067 cases would be in children under 1 year of age. Studies indicate that RSV hospitalization rates among infants (0–11 months) range from 13 to 26 per 1,000 children annually. In 2023, approximately 953,000 children were born in Turkey. Therefore, an estimated 12,000 to 25,000 infants may have been hospitalized due to RSV in 2023. Our study indicates that 70% of RSV-related PICU admissions were in infants under 12 months, and 55% were under 6 months. There were approximately 947 PICU admissions for infants under 12 months and about 744 PICU admissions for infants under 6 months, according to this estimation. For the prevention of RSV infection, there are strategies infection control measures (hand hygiene and cohorting in the hospital, maternal RSV vaccination and monoclonal antibodies. 1 The RSVpreF (Abrysvo®, Pfizer) vaccine, a bivalent prefusion F protein vaccine, is licensed in many countries—including recently in Türkiye—for use in pregnant individuals and at-risk adults. 1 , 15 In Argentina, vaccine effectiveness against RSV-associated LRTI leading to infant hospitalisation was 78·6% from birth to age 3 months and 71·3% from birth to age 6 months. Effectiveness against RSV-associated severe LRTI leading to hospitalisation was 76·9% from birth to age 6 months. 16 Palivizumab, while effective in high-risk groups including for premature infants and those with cyanotic CHD, requires monthly injections. 17 Nirsevimab, a long-acting monoclonal antibody, provides passive immunity to infants throughout their first RSV season with a single intramuscular injection. Nirsevimab was associated with a lower odds of RSV-related hospitalisation (odds ratio 0·17; 95% CI 0·12–0·23), a lower odds of ICU admission (0·19; 0·12–0·29), and a lower odds of LRTI incidence (0·25; 0·19–0·33) in infants aged 0–12 months. In the United States hospitalization, rates during the 2024–2025 RSV season, hospitalization rates among infants aged 0–7 months decreased by 28% to 43% compared to pre-pandemic seasons, attributed to the introduction of maternal RSV vaccines and monoclonal antibody treatments. 18 These findings demonstrate the important role of both maternal vaccination and nirsevimab prophylaxis in reducing severe RSV-related outcomes in infants, including the need for PICU admission. Nirsevimab has not started to be used in Türkiye, and our study will be a background for both maternal RSV vaccine and/or nirsevimab use effectiveness in the future, and pediatric intensive care unit studies would be a probe for these interventions. Our study has some limitations. As with all retrospective studies, there is potential for missing data, documentation bias, and inconsistency in clinical definitions or reporting practices across centers. The absence of a comparison group (e.g., RSV patients not requiring PICU or patients with non-RSV bronchiolitis) limits the ability to infer risk associations beyond descriptive outcomes. Lack of RSV subtypes (A vs. B), and viral load can influence severity and outcomes. While large, it’s unclear whether centers represent all regions of Türkiye or whether data is skewed toward tertiary/referral hospitals, possibly overestimating severity. Our study represents one of the largest multicenter pediatric intensive care analyses of RSV infection in Türkiye and worldwide, covering a period that includes both the COVID-19 pandemic and post-pandemic resurgence. Our cohort includes a broad age range (1 month to 18 years), capturing both typical infant cases and rarer older pediatric cases. Our study provides critical data on age distribution, and underlying conditions, with implications for both clinical risk stratification and health policy. Our study showed that pediatric ARDS (12.7%) is an important clinical picture in PICU and would be an important outcome for prevention strategies. Underlying disease as a significant mortality risk factor for pARDS and mortality highlights the importance of these patients for potential prevention strategies. In 2023, Türkiye likely experienced approximately 1,353 requiring PICU care. Notably, infants under 12 months constituted the majority of severe cases, emphasizing the need for targeted preventive measures in this age group. One of the first detailed, multicenter PICU studies on RSV in Türkiye, providing crucial local epidemiological insight and background data for potential monoclonal antibodies and/or vaccine implementation. We will start the prospective RSV surveillance in PICUs in Türkiye in October 2025 until 2028. Declarations Data collection Yasemin Coban, Gultac Evren, Analysis and interpretation of data Ener Cagri Dinleyici, Yasemin Coban Drafting the article Ener Cagri Dinleyici, Yasemin Coban Critical revision of its substantial intellectual content Ener Cagrı Dinleyici, Dincer Yildizdas Author Contribution Substantial contributions to conception and design of the study: Yasemin CobanSend Data From Centers: YC,GC, DY, NZ, AB, TK, MH, EE, MD, AA, NY, HEKK, MU, EK, GB, MAK, NA, MC, ES, SE, HCT, FA, AA, NA, OD, NUK, AK, MUY, EA, NA, CO, DA, FE, OOH, ET, FI, NYÖ, AEA, MA, MM, RY, AK, ECDData collection: Yasemin Coban, Gultac Evren,Analysis and interpretation of data: Ener Cagri Dinleyici **,** Yasemin CobanDrafting the article: Ener Cagri Dinleyici, Yasemin CobanCritical revision of its substantial intellectual content: Ener Cagrı Dinleyici, Dincer YildizdasFinal approval of the version to be published: Ener Cagri Dinleyici Yasemin Coban All authors fully meet the following criteria for authorship: Substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; AND Drafting the work or revising it critically for important intellectual content; AND Final approval of the version to be published; AND Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. References WHO position (2025) paper on immunization to protect infants against respiratory syncytial virus disease, May 2025. Wkly Epidemiol Records 100:193–218 Li Y, Wang X, Blau DM, Caballero MT et al (2022) Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in children younger than 5 years in 2019: a systematic analysis. Lancet 399(10340):2047–2064. 10.1016/S0140-6736(22)00478-0 Groothuis JR, Hoopes JM, Jessie VG (2011) Prevention of serious respiratory syncytial virus-related illness. I: Disease pathogenesis and early attempts at prevention. Adv Ther 28(2):91–109. 10.1007/s12325-010-0100-z Halasa N, Zambrano LD, Amarin JZ et al (2023) Infants Admitted to US Intensive Care Units for RSV Infection During the 2022 Seasonal Peak. JAMA Netw Open 6(8):e2328950. 10.1001/jamanetworkopen.2023.28950 Shanklin A, Olson T, Patel AK et al (2024) Respiratory Syncytial Virus and US Pediatric Intensive Care Utilization. JAMA Netw Open 7(10):e2440997. 10.1001/jamanetworkopen.2024.40997 Phijffer EWEM, Wildenbeest JG, Brouwer CNM et al (2025) The Full Burden of RSV-related Pediatric Intensive Care Unit Admissions During Infancy: A Prospective National Study (BRICK Study). Pediatr Infect Dis J 44(6):517–521. 10.1097/INF.0000000000004712 Hall CB, Weinberg GA, Iwane MK et al (2009) The burden of respiratory syncytial virus infection in young children. N Engl J Med 360(6):588–598. 10.1056/NEJMoa0804877 Fonseca MJ, Hagenaars S, Bangert M et al (2024) Respiratory Syncytial Virus Hospital Admission Rates and Patients' Characteristics Before the Age of 2 Years in England, 2015–2019. Pediatr Infect Dis J 43(9):909–915. 10.1097/INF.0000000000004467 Nye S, Whitley RJ, Kong M (2016) Viral Infection in the Development and Progression of Pediatric Acute Respiratory Distress Syndrome. Front Pediatr 4:128. 10.3389/fped.2016.00128 Peña-López Y, Sabater-Riera J, Raj P (2024) Severe respiratory syncytial virus disease. J Intensive Med 4(4):405–416. 10.1016/j.jointm.2024.03.001 Nye S, Whitley RJ, Kong M (2016) Viral Infection in the Development and Progression of Pediatric Acute Respiratory Distress Syndrome. Front Pediatr 4:128. 10.3389/fped.2016.00128 Dahlem P, van Aalderen WM, Hamaker ME et al (2003) Incidence and short-term outcome of acute lung injury in mechanically ventilated children. Eur Respir J 22(6):980–985. 10.1183/09031936.03.00003303 Houben ML, Coenjaerts FEJ, Rossen JWA et al (2010) Disease severity and viral load are correlated in infants with primary respiratory syncytial virus infection in the community. J Med Virol 82:1266–1271. 10.1002/jmv.21771 Szabo SM, Gooch KL, Bibby MM et al (2013) The risk of mortality among young children hospitalized for severe respiratory syncytial virus infection. Paediatr Respir Rev 13(Suppl 2):S1–8. 10.1016/S1526-0542(12)00095-4 Kampmann B, Madhi SA, Munjal I et al (2023) Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants. N Engl J Med 388(16):1451–1464. 10.1056/NEJMoa2216480 Pérez Marc G, Vizzotti C, Fell DB et al (2025) Real-world effectiveness of RSVpreF vaccination during pregnancy against RSV-associated lower respiratory tract disease leading to hospitalisation in infants during the 2024 RSV season in Argentina (BERNI study): a multicentre, retrospective, test-negative, case-control study. Lancet Infect Dis 3099(25):S1473. 10.1016/S1473-3099(25)00156-2 Caserta MT, O'Leary ST, Munoz FM et al (2023) Palivizumab Prophylaxis in Infants and Young Children at Increased Risk of Hospitalization for Respiratory Syncytial Virus Infection. Pediatrics 152(1):e2023061803. 10.1542/peds.2023-061803 Patton ME, Moline HL, Whitaker M et al (2025) Interim Evaluation of Respiratory Syncytial Virus Hospitalization Rates Among Infants and Young Children After Introduction of Respiratory Syncytial Virus Prevention Products - United States, October 2024-February 2025. MMWR Morb Mortal Wkly Rep 74(16):273–281. 10.15585/mmwr.mm7416a1 Additional Declarations No competing interests reported. Supplementary Files SupplementaryTable12.docx Cite Share Download PDF Status: Posted Version 1 posted 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7691297","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":532972919,"identity":"c1640b7a-312f-4b6f-8218-e4746cb96e67","order_by":0,"name":"Yasemin 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1","display":"","copyAsset":false,"role":"figure","size":122747,"visible":true,"origin":"","legend":"\u003cp\u003eAge distribution of children with RSV requiring PICU stay.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7691297/v1/75ea1defa9a8070afc17e7f8.png"},{"id":94225378,"identity":"0cb65247-b014-411a-9242-0d16840c8a99","added_by":"auto","created_at":"2025-10-23 19:29:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":122135,"visible":true,"origin":"","legend":"\u003cp\u003eMonthly distribution of RSV cases between 2020-2024. Limited cases have been reported first two years of COVID-19 pandemic and resurgence have been observed since 2022 autumn.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7691297/v1/0b03f959216b10f4224d8bec.png"},{"id":96252644,"identity":"15628eb3-c552-4f0d-bfdd-5358493a7286","added_by":"auto","created_at":"2025-11-19 07:41:19","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1198707,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7691297/v1/89434d08-244c-4f34-adf9-3a144e07aa4d.pdf"},{"id":94225387,"identity":"41587bad-90db-424c-ad7f-7d981999126a","added_by":"auto","created_at":"2025-10-23 19:29:22","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":16995,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryTable12.docx","url":"https://assets-eu.researchsquare.com/files/rs-7691297/v1/ad561995eda1db06e2d9fd11.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Burden, Risk Factors, and Outcomes of RSV Infection in Pediatric ICUs Across Türkiye: RSVP Study","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003eRespiratory syncytial virus (RSV) is a leading cause of acute lower respiratory infections and associated hospitalizations in infants and children globally. \u003csup\u003e1\u003c/sup\u003e In 2019, there were 33\u0026nbsp;million RSV-associated cases of acute lower respiratory airway infection, 3.6\u0026nbsp;million RSV-associated hospital admissions, and 101,400 RSV-attributable deaths in children under 5 years of age.\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e Initial RSV infection often occurs in the first year of life, with almost all children infected by their second birthday .\u003csup\u003e3\u003c/sup\u003e More than 97% of pediatric RSV-related deaths occurred in low- and middle-income countries.\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eIn T\u0026uuml;rkiye, there is limited data available for RSV hospitalization and PICU requirements, representing the whole country. To understand the full clinical impact of potential RSV prevention, insight into the yet unseen burden of severe RSV disease will be helpful. The aim of this study was to evaluate the distribution of age and risk factors among patients admitted to the pediatric intensive care unit due to RSV from 2020 to 2024 and define the clinical course in the PICU.\u003c/p\u003e"},{"header":"2. PATIENTS AND METHOD","content":"\u003cp\u003e\u003cstrong\u003e2.1. \u003cstrong\u003eStudy Design and Setting:\u0026nbsp;\u003c/strong\u003e\u003c/strong\u003eThis study is a\u0026nbsp;\u003cstrong\u003eretrospective, multicenter cohort analysis\u003c/strong\u003e conducted in PICUs across T\u0026uuml;rkiye. Data were collected from children diagnosed with laboratory-confirmed RSV infection who were admitted to participating PICUs between\u0026nbsp;\u003cstrong\u003eJanuary 1, 2020, and December 31, 2024\u003c/strong\u003e\u003cstrong\u003e.\u003c/strong\u003e The study included data from multiple tertiary hospitals located in various regions of T\u0026uuml;rkiye. This retrospective study was conducted in accordance with the Declaration of Helsinki (1964 and its later amendments). The study was approved by the Local Ethical Committee of the Mugla Sıtkı Kocman University Faculty of Medicine on 13.01.2025, decision number 5. Following authorization from the local ethical committee, we collected medical records of patients diagnosed with RSV from 23 centers in 14 different cities. Human Ethics and Participation Consent statements: not applicable\u0026rsquo; as it is retrospective.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2. \u003cstrong\u003ePatient Selection\u003c/strong\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatients were eligible for inclusion if they met the following criteria:\u003c/p\u003e\n\u003cp\u003e\u0026middot; Age between\u0026nbsp;\u003cstrong\u003e1 month and 18 years\u003c/strong\u003e at the time of PICU admission.\u003c/p\u003e\n\u003cp\u003e\u0026middot; \u003cstrong\u003eConfirmed RSV infection\u003c/strong\u003e via polymerase chain reaction (PCR)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026middot; Admitted to a participating PICU during the study period.\u003c/p\u003e\n\u003cp\u003ePatients hospitalized in the newborn intensive care unit have not been evaluated. Cases with incomplete medical records or uncertain RSV diagnoses were also excluded.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3. \u003cstrong\u003eData Collection\u003c/strong\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData were obtained from electronic and paper-based medical records. Extracted variables included:\u0026nbsp;\u003cstrong\u003edemographics\u003c/strong\u003e (age, sex, birth history, and neonatal intensive care unit (NICU) \u0026nbsp;admission history, p\u003cstrong\u003erematurity\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003ewas defined as 37 weeks),\u0026nbsp;\u003cstrong\u003eclinical history\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e (presence of prematurity, congenital heart disease, chronic respiratory or neurological conditions, genetic syndromes (e.g., Down syndrome), or other underlying illnesses.\u003c/p\u003e\n\u003cp\u003e\u0026middot; \u003cstrong\u003eRSV-related diagnosis\u003c/strong\u003e: bronchiolitis, pneumonia, pediatric acute respiratory distress syndrome (pARDS) and complications such as pleural effusion, pneumothorax, apnea, myocarditis, and seizures.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026middot; \u003cstrong\u003eTreatment modalities\u003c/strong\u003e: type of respiratory support.\u003c/p\u003e\n\u003cp\u003e\u0026middot; \u003cstrong\u003eOutcomes\u003c/strong\u003e: PICU length of stay, total hospital stay, and in-hospital mortality.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4.\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Outcomes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePrimary outcome\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e-\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/strong\u003eDistribution of age and risk factors among patients admitted to the pediatric intensive care unit due to RSV from 2020 to 2024.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSecondary outcomes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e- Characteristics of patients who develop pARDS, comparison of patients who develop pARDS and those who do not develop\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Determining the characteristics of patients death due to RSV infection and comparing them with surviving patients\u003c/p\u003e\n\u003cp\u003e- The early period of the pandemic, the easing restrictions period, and the evaluation of changes in the number of RSV infection cases and seasonality after the pandemic\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.5.\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Statistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistical analysis was performed using the\u0026nbsp;\u003cstrong\u003eJASP\u003c/strong\u003e statistical program.\u0026nbsp;\u003c/p\u003e"},{"header":"3. RESULTS","content":"\u003cp\u003eThe study included 646 children (360 boys, 286 girls) admitted to intensive care units with RSV infection between January 1, 2020, and December 31,2024. Patient ages ranged from 1 to 214 months (median: 5 months). Of these, 149 were aged 1-2 months, 358 were younger than 6 months, and 465 were younger than 1 year. In total, 492 cases were under 2 years and 577 were under 5 years. Seventy patients were between 6 and 18 years of age \u0026nbsp;(Figure 1).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe distribution of cases was 73 in 2020, 48 in 2021, 130 in 2022, 227 in 2023, and 168 in 2024. In T\u0026uuml;rkiye, the first COVID-19 patient detected in March 2020, and restriction policies started at this date. There are limited cases that have been seen from March 2020 to September 2022. Since September 2022, in 2022-2023 and 2024, resurgences of RSV infection have been noted, peaking at November to January (Figure 2).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOf the cases, 388 were delivered via C-section, while 258 were delivered vaginally. Of the cases, 139 were preterm (21.5%), whereas 507 were term births (78.5%). The gestational week in cases with a history of premature birth was 32.9 \u0026plusmn; 2.96 weeks (ranging from 23 to 36 weeks). A total of 174 cases (26.9%) were previously monitored in the neonatal intensive care unit. In 190 instances (29.4%), a history of underlying disease was noted, while 58 instances involved congenital heart disease (Table 1). None of the patients received palivizumab prophylaxis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1. Presence of underlying condition in patients with RSV infection in PICU.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"3\" cellpadding=\"0\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eUnderlying Condition\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eCongenital Heart Disease Type\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eN=58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eVSD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eASD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eASD/VSD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003ePDA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eASD/VSD/PDA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eAortic Coarctation\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eTOF (Tetralogy of Fallot)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eVSD + PDA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eASD + PS (Pulmonary Stenosis)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eBicuspid Aortic Valve\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCardiomyopathy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eDouble Aortic Arch\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eASD + VSD + Aortic Coarctation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eASD + PDA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eTransposition of great arteries\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eEpilepsy / Epileptic Syndrome\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eCerebral Palsy with Epilepsy\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eBronchopulmonary Dysplasia (BPD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eDown Syndrome\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eHematologic / Oncologic Disease\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eGenetic Syndromes\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eNeuromotor Retardation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eImmunodeficiency\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eSpinal Muscular Atrophy (SMA)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eAsthma\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eMetabolic Disease\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eAllergic Disorders\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eDiabetes Mellitus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eEsophageal Atresia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eChronic Lung Disease/Cystic fibrosis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCongenital Infection\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCleft Lip and Palate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eOsteogenesis Imperfecta\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCongenital Muscular Dystrophy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eOther\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cul\u003e\n \u003cli\u003eCongenital heart disease have been isolated cardiac defects of associated with other underling disorders\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eOf the 646 cases, 246 (38.1%) were hospitalized for bronchiolitis, 386 (59.8%) for pneumonia, and 14 for other reasons. \u0026nbsp;Complications included pleural effusion ( n=8), pneumothorax (n=8), central nervous system findings and convulsions (n=19), apnea (n=10) and myocarditis (n=5). \u0026nbsp;pARDS was established in 82 cases (12.7%) and 2 \u0026nbsp;required ECMO. Overall, 35 patients died (mortality: 5.4%). The median length of stay in PICU was 6 days (range: 1-155 days), and median hospital stay was 9 days (range: 1-155 days).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;On PICU admission, 102 patients received oxygen therapy, 381 patients received HFNC, 57 patients received NIV-ST, and 106 patients required invasive mechanical ventilation. During the follow-up, 377 required HFNC, 96 required NIV-ST, and 165 (25.5%) required invasive mechanical ventilation.\u003c/p\u003e\n\u003cp\u003eRSV co-infections were identified in 169 patients. The most frequent were rhinovirus/enterovirus (n=57), influenza A (n=23), coronaviruses N63/OC43/HKU (n= 17), adenovirus (n=15), SARS-CoV-2 (n=12). Less common agents included parainfluenza, bocavirus, parechovirus, and multi-virus combinations (Supplementary Table 1). These findings underscore the clinical impact of viral co-infections in RSV cases.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA total of 82 patients were diagnosed with pARDS ( 32 girls, 50 boys; median age: 6 months, range: 1-151 months). Cases occurred most frequently in December (n=30) and January (n=24). Cesarean delivery was reported in 62.2 %, incuding 20 preterm and 62 term births. Underlying diseases were present in 39 patients (47.6%), including 16 with congenital heart disease. Overall, 56 had mild/moderate and 26 severe pARDS. Eight patients died, yielding a mortality rate of 9.8%.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSecondary infections were identified in 49 RSV cases. The most common pathogens were \u0026nbsp;\u003cem\u003eStreptococcus pneumoniae\u003c/em\u003e and \u003cem\u003ePseudomonas aeruginosa\u003c/em\u003e (10 cases each), followed by \u003cem\u003eHaemophilus influenzae\u003c/em\u003e (7) and \u003cem\u003eStaphylococcus aureus\u003c/em\u003e (5). Less frequent pathogens included \u003cem\u003eKlebsiella pneumoniae, Acinetobacter spp., Candida spp\u003c/em\u003e., and various other bacteria, such as \u003cem\u003eStenotrophomonas maltophilia, Streptococcus pyogenes, and E. coli\u003c/em\u003e (Supplementary Table 2).\u003c/p\u003e\n\u003cp\u003eOnly the presence of underlying disease (OR 3.149; 0.787-3.383, p\u0026lt;0.01). When we checked below one year of age, again only the presence of underlying disease (OR 3.567; p\u0026lt;0.01).\u003c/p\u003e\n\u003cp\u003eAmong the 35 deceased patients, 15 were male and 20 were female. Twenty-one cases were delivered via cesarean section, while fourteen cases were delivered vaginally. Ten cases were classified as premature, while twenty-five cases were categorized as term. Thirteen cases exhibited a history of admission to the neonatal intensive care unit. Among the deceased cases, 27 exhibited a history of underlying disease, while 5 cases involved congenital heart disease. The mortality risk in patients with underlying diseases was significantly higher than in those without such conditions (OR 2.22; 95% CI 1.38-3.17; p\u0026lt; .001).\u003c/p\u003e"},{"header":"4. DISCUSSION","content":"\u003cp\u003eThis is one of the largest clinical studies, including 646 children with RSV in PICUs across T\u0026uuml;rkiye. In the present study, 76.1% of the patients are below two years of age, 72% are below one year of age, and 55.4% were below 6 months of age. 23% of the patients are 1\u0026ndash;2 months of age, and this age period is the peak of PICU stay. In our PICU cohort, 21.5% were preterm births, 8.7% had congenital heart disease, and 70.6% were previously healthy. Our findings are consistent with global patterns, particularly the high burden among infants\u0026thinsp;\u0026lt;\u0026thinsp;12 months. Halasa et al. \u003csup\u003e4\u003c/sup\u003e showed that 65% of children requiring PICU stay are below 1 year of age, 5\u0026ndash;10% have congenital heart disease, and 20% were prematurely born in the US. Another study from United States showed that 63% of patients were below 1 year old, 8% had congenital heart disease, 15\u0026ndash;20% were preterm.\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e Regarding the Brick Study, a nationwide, prospective, observational, multicenter study which was performed in the Netherlands, of 423 patients, median age was 46 days, 72.9% were term born and 69% had no comorbidities.\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e Young age (\u0026lt;\u0026thinsp;6 months) is an independent risk factor even without comorbidities.\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e In our study neurological disorders are important underlying conditions for RSV infection requiring PICU. BPD and other chronic pulmonary disorders, Down syndrome, and immune deficiencies are important risk factors. The presence of underlying disorders 3-fold increased the pARDS and also 2.2-fold increased the mortality. A study analyzing data from England estimated RSV hospitalization rates in infants up to 24 months old, highlighting higher rates among those with risk factors such as chronic lung disease and congenital heart disease.\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e While underlying disorders are important for the severity and mortality of the disease, 70.6% of children with RSV who required PICU stays were previously healthy. Preventive strategies are essential for healthy infants as well as infants with underlying disorders.\u003c/p\u003e\u003cp\u003eNo specific treatment exists for RSV disease. Infants with RSV disease require supportive treatment.\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e In our study, on PICU admission, 58.9% of patients received HFNC, 8.8% of patients NIV-ST, and 16.5% of patients required invasive mechanical ventilation. During the follow-up, patients required invasive mechanical ventilation. Increased to 25.5%. Previous studies showed different invasive mechanical ventilation requirements, varying from 24% to 61.1%\u003csup\u003e4\u0026ndash;5\u003c/sup\u003e. Among children hospitalized with RSV, approximately 29.7% required positive pressure ventilation, and 22.3% required invasive mechanical ventilation in the United States.\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eThe development of ARDS in children with RSV infection is less common but can occur, particularly in severe cases \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. In our cohort of 82 cases diagnosed with pARDS, the median age was 6 months. Among these cases, 24.4% were premature, 47.6% had underlying conditions, and 19.5% had congenital cardiac disease. 64.6% of pARDS cases are moderate or severe, and the mortality rate was 9.8%. A study reported that among children under 2 years admitted to the PICU with RSV infection, the incidence of ARDS was approximately 20%, with 7% classified as severe pARDS.\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e Another study observed that 15.9% of children with RSV infection developed ARDS.\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e An earlier study reported a 15.9% incidence of ARDS in children with RSV infection in the Netherlands. \u003csup\u003e12\u003c/sup\u003e The variability in PICU admission rates, mechanical ventilation requirements, and ARDS incidence highlights the need for continued surveillance and targeted preventive strategies.\u003c/p\u003e\u003cp\u003eIn addition to severe respiratory distress, different acid-base disorders including respiratory or metabolic acidosis, and need for high oxygen supplementation, co- or superinfection have an increased risk of complications and PICU need.\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e In this cohort, the most common co-infection was rhinovirus/enterovirus, followed by influenza A, coronaviruses NL63, OC43, and HKU, adenovirus, and SARS-CoV-2. These findings highlight the significant role of respiratory viral co-infections in children with RSV, which may complicate clinical management and outcomes. In our study, 7.6% of children were complicated with bacterial and Candida infections, mainly \u003cem\u003eStreptococcus pneumoniae\u003c/em\u003e and \u003cem\u003ePseudomonas aeruginosa\u003c/em\u003e. This spectrum indicates that there must be vigilance regarding bacterial and fungal superinfections in children with RSV, which may impact disease severity and management. Some studies suggest higher viral loads correlate with more severe disease\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e; however, we did not perform analysis for viral loads. Prevention strategies against viral, bacterial, and fungal diseases (influenza and pneumococcal conjugated vaccine and infection prevention strategies bundles in PICU) are essential. In our study the mortality rate was 5.4%, mostly with comorbidities. A systematic review of severe RSV cases reported a case fatality range of 1.9% to 5.9% in hospitalized pediatric patients.\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e\u003cp\u003e In our study, 2023, 203 children were admitted to PICUs in participating centers due to RSV infection, with 160 of these children under the age of 1 year (excluding those under 1 month). These centers represent approximately 15% of the total PICU beds in Turkiye. Extrapolating from this data, the estimated total number of RSV-related PICU admissions nationwide would be approximately 1,353 cases, and of these, approximately 1,067 cases would be in children under 1 year of age. Studies indicate that RSV hospitalization rates among infants (0\u0026ndash;11 months) range from 13 to 26 per 1,000 children annually. In 2023, approximately 953,000 children were born in Turkey. Therefore, an estimated 12,000 to 25,000 infants may have been hospitalized due to RSV in 2023. Our study indicates that 70% of RSV-related PICU admissions were in infants under 12 months, and 55% were under 6 months. There were approximately 947 PICU admissions for infants under 12 months and about 744 PICU admissions for infants under 6 months, according to this estimation.\u003c/p\u003e\u003cp\u003eFor the prevention of RSV infection, there are strategies infection control measures (hand hygiene and cohorting in the hospital, maternal RSV vaccination and monoclonal antibodies.\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e The RSVpreF (Abrysvo\u0026reg;, Pfizer) vaccine, a bivalent prefusion F protein vaccine, is licensed in many countries\u0026mdash;including recently in T\u0026uuml;rkiye\u0026mdash;for use in pregnant individuals and at-risk adults.\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e In Argentina, vaccine effectiveness against RSV-associated LRTI leading to infant hospitalisation was 78\u0026middot;6% from birth to age 3 months and 71\u0026middot;3% from birth to age 6 months. Effectiveness against RSV-associated severe LRTI leading to hospitalisation was 76\u0026middot;9% from birth to age 6 months.\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e Palivizumab, while effective in high-risk groups including for premature infants and those with cyanotic CHD, requires monthly injections.\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e Nirsevimab, a long-acting monoclonal antibody, provides passive immunity to infants throughout their first RSV season with a single intramuscular injection. Nirsevimab was associated with a lower odds of RSV-related hospitalisation (odds ratio 0\u0026middot;17; 95% CI 0\u0026middot;12\u0026ndash;0\u0026middot;23), a lower odds of ICU admission (0\u0026middot;19; 0\u0026middot;12\u0026ndash;0\u0026middot;29), and a lower odds of LRTI incidence (0\u0026middot;25; 0\u0026middot;19\u0026ndash;0\u0026middot;33) in infants aged 0\u0026ndash;12 months. In the United States hospitalization, rates during the 2024\u0026ndash;2025 RSV season, hospitalization rates among infants aged 0\u0026ndash;7 months decreased by 28% to 43% compared to pre-pandemic seasons, attributed to the introduction of maternal RSV vaccines and monoclonal antibody treatments.\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e These findings demonstrate the important role of both maternal vaccination and nirsevimab prophylaxis in reducing severe RSV-related outcomes in infants, including the need for PICU admission. Nirsevimab has not started to be used in T\u0026uuml;rkiye, and our study will be a background for both maternal RSV vaccine and/or nirsevimab use effectiveness in the future, and pediatric intensive care unit studies would be a probe for these interventions.\u003c/p\u003e\u003cp\u003eOur study has some limitations. As with all retrospective studies, there is potential for missing data, documentation bias, and inconsistency in clinical definitions or reporting practices across centers. The absence of a comparison group (e.g., RSV patients not requiring PICU or patients with non-RSV bronchiolitis) limits the ability to infer risk associations beyond descriptive outcomes. Lack of RSV subtypes (A vs. B), and viral load can influence severity and outcomes. While large, it\u0026rsquo;s unclear whether centers represent all regions of T\u0026uuml;rkiye or whether data is skewed toward tertiary/referral hospitals, possibly overestimating severity.\u003c/p\u003e\u003cp\u003e Our study represents one of the largest multicenter pediatric intensive care analyses of RSV infection in T\u0026uuml;rkiye and worldwide, covering a period that includes both the COVID-19 pandemic and post-pandemic resurgence. Our cohort includes a broad age range (1 month to 18 years), capturing both typical infant cases and rarer older pediatric cases. Our study provides critical data on age distribution, and underlying conditions, with implications for both clinical risk stratification and health policy. Our study showed that pediatric ARDS (12.7%) is an important clinical picture in PICU and would be an important outcome for prevention strategies. Underlying disease as a significant mortality risk factor for pARDS and mortality highlights the importance of these patients for potential prevention strategies. In 2023, T\u0026uuml;rkiye likely experienced approximately 1,353 requiring PICU care. Notably, infants under 12 months constituted the majority of severe cases, emphasizing the need for targeted preventive measures in this age group. One of the first detailed, multicenter PICU studies on RSV in T\u0026uuml;rkiye, providing crucial local epidemiological insight and background data for potential monoclonal antibodies and/or vaccine implementation. We will start the prospective RSV surveillance in PICUs in T\u0026uuml;rkiye in October 2025 until 2028.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData collection\u003c/strong\u003e\u003cp\u003eYasemin Coban, Gultac Evren,\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eAnalysis and interpretation of data\u003c/strong\u003e\u003cp\u003eEner Cagri Dinleyici, Yasemin Coban\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eDrafting the article\u003c/strong\u003e\u003cp\u003eEner Cagri Dinleyici, Yasemin Coban\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCritical revision of its substantial intellectual content\u003c/strong\u003e\u003cp\u003eEner Cagrı Dinleyici, Dincer Yildizdas\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eSubstantial contributions to conception and design of the study: Yasemin CobanSend Data From Centers: YC,GC, DY, NZ, AB, TK, MH, EE, MD, AA, NY, HEKK, MU, EK, GB, MAK, NA, MC, ES, SE, HCT, FA, AA, NA, OD, NUK, AK, MUY, EA, NA, CO, DA, FE, OOH, ET, FI, NY\u0026Ouml;, AEA, MA, MM, RY, AK, ECDData collection: Yasemin Coban, Gultac Evren,Analysis and interpretation of data: Ener Cagri Dinleyici **,** Yasemin CobanDrafting the article: Ener Cagri Dinleyici, Yasemin CobanCritical revision of its substantial intellectual content: Ener Cagrı Dinleyici, Dincer YildizdasFinal approval of the version to be published: Ener Cagri Dinleyici Yasemin Coban\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eAll authors fully meet the following criteria for authorship:\u003c/strong\u003e\u003c/p\u003e\n\u003col start=\"1\" type=\"1\"\u003e\n \u003cli\u003eSubstantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; AND\u003c/li\u003e\n \u003cli\u003eDrafting the work or revising it critically for important intellectual content; AND\u003c/li\u003e\n \u003cli\u003eFinal approval of the version to be published; AND\u003c/li\u003e\n \u003cli\u003eAgreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWHO position (2025) paper on immunization to protect infants against respiratory syncytial virus disease, May 2025. Wkly Epidemiol Records 100:193\u0026ndash;218\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi Y, Wang X, Blau DM, Caballero MT et al (2022) Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in children younger than 5 years in 2019: a systematic analysis. Lancet 399(10340):2047\u0026ndash;2064. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/S0140-6736(22)00478-0\u003c/span\u003e\u003cspan address=\"10.1016/S0140-6736(22)00478-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGroothuis JR, Hoopes JM, Jessie VG (2011) Prevention of serious respiratory syncytial virus-related illness. I: Disease pathogenesis and early attempts at prevention. Adv Ther 28(2):91\u0026ndash;109. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s12325-010-0100-z\u003c/span\u003e\u003cspan address=\"10.1007/s12325-010-0100-z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHalasa N, Zambrano LD, Amarin JZ et al (2023) Infants Admitted to US Intensive Care Units for RSV Infection During the 2022 Seasonal Peak. JAMA Netw Open 6(8):e2328950. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1001/jamanetworkopen.2023.28950\u003c/span\u003e\u003cspan address=\"10.1001/jamanetworkopen.2023.28950\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShanklin A, Olson T, Patel AK et al (2024) Respiratory Syncytial Virus and US Pediatric Intensive Care Utilization. JAMA Netw Open 7(10):e2440997. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1001/jamanetworkopen.2024.40997\u003c/span\u003e\u003cspan address=\"10.1001/jamanetworkopen.2024.40997\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePhijffer EWEM, Wildenbeest JG, Brouwer CNM et al (2025) The Full Burden of RSV-related Pediatric Intensive Care Unit Admissions During Infancy: A Prospective National Study (BRICK Study). Pediatr Infect Dis J 44(6):517\u0026ndash;521. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/INF.0000000000004712\u003c/span\u003e\u003cspan address=\"10.1097/INF.0000000000004712\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHall CB, Weinberg GA, Iwane MK et al (2009) The burden of respiratory syncytial virus infection in young children. N Engl J Med 360(6):588\u0026ndash;598. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1056/NEJMoa0804877\u003c/span\u003e\u003cspan address=\"10.1056/NEJMoa0804877\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFonseca MJ, Hagenaars S, Bangert M et al (2024) Respiratory Syncytial Virus Hospital Admission Rates and Patients' Characteristics Before the Age of 2 Years in England, 2015\u0026ndash;2019. Pediatr Infect Dis J 43(9):909\u0026ndash;915. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/INF.0000000000004467\u003c/span\u003e\u003cspan address=\"10.1097/INF.0000000000004467\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNye S, Whitley RJ, Kong M (2016) Viral Infection in the Development and Progression of Pediatric Acute Respiratory Distress Syndrome. Front Pediatr 4:128. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fped.2016.00128\u003c/span\u003e\u003cspan address=\"10.3389/fped.2016.00128\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePe\u0026ntilde;a-L\u0026oacute;pez Y, Sabater-Riera J, Raj P (2024) Severe respiratory syncytial virus disease. J Intensive Med 4(4):405\u0026ndash;416. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jointm.2024.03.001\u003c/span\u003e\u003cspan address=\"10.1016/j.jointm.2024.03.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNye S, Whitley RJ, Kong M (2016) Viral Infection in the Development and Progression of Pediatric Acute Respiratory Distress Syndrome. Front Pediatr 4:128. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fped.2016.00128\u003c/span\u003e\u003cspan address=\"10.3389/fped.2016.00128\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDahlem P, van Aalderen WM, Hamaker ME et al (2003) Incidence and short-term outcome of acute lung injury in mechanically ventilated children. Eur Respir J 22(6):980\u0026ndash;985. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1183/09031936.03.00003303\u003c/span\u003e\u003cspan address=\"10.1183/09031936.03.00003303\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHouben ML, Coenjaerts FEJ, Rossen JWA et al (2010) Disease severity and viral load are correlated in infants with primary respiratory syncytial virus infection in the community. J Med Virol 82:1266\u0026ndash;1271. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/jmv.21771\u003c/span\u003e\u003cspan address=\"10.1002/jmv.21771\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSzabo SM, Gooch KL, Bibby MM et al (2013) The risk of mortality among young children hospitalized for severe respiratory syncytial virus infection. Paediatr Respir Rev 13(Suppl 2):S1\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/S1526-0542(12)00095-4\u003c/span\u003e\u003cspan address=\"10.1016/S1526-0542(12)00095-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKampmann B, Madhi SA, Munjal I et al (2023) Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants. N Engl J Med 388(16):1451\u0026ndash;1464. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1056/NEJMoa2216480\u003c/span\u003e\u003cspan address=\"10.1056/NEJMoa2216480\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eP\u0026eacute;rez Marc G, Vizzotti C, Fell DB et al (2025) Real-world effectiveness of RSVpreF vaccination during pregnancy against RSV-associated lower respiratory tract disease leading to hospitalisation in infants during the 2024 RSV season in Argentina (BERNI study): a multicentre, retrospective, test-negative, case-control study. Lancet Infect Dis 3099(25):S1473. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/S1473-3099(25)00156-2\u003c/span\u003e\u003cspan address=\"10.1016/S1473-3099(25)00156-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCaserta MT, O'Leary ST, Munoz FM et al (2023) Palivizumab Prophylaxis in Infants and Young Children at Increased Risk of Hospitalization for Respiratory Syncytial Virus Infection. Pediatrics 152(1):e2023061803. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1542/peds.2023-061803\u003c/span\u003e\u003cspan address=\"10.1542/peds.2023-061803\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePatton ME, Moline HL, Whitaker M et al (2025) Interim Evaluation of Respiratory Syncytial Virus Hospitalization Rates Among Infants and Young Children After Introduction of Respiratory Syncytial Virus Prevention Products - United States, October 2024-February 2025. MMWR Morb Mortal Wkly Rep 74(16):273\u0026ndash;281. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.15585/mmwr.mm7416a1\u003c/span\u003e\u003cspan address=\"10.15585/mmwr.mm7416a1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"respiratory syncytial virus, RSV, pARDS","lastPublishedDoi":"10.21203/rs.3.rs-7691297/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7691297/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eRespiratory syncytial virus (RSV) is one of the leading causes of requiring a pediatric intensive care unit (PICU). This study aimed to characterize the clinical features, complications, co-infections, and risk factors associated with RSV-related morbidity and mortality in a large PICU cohort over five years.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis is a retrospective multicenter study to evaluate patients with RSV infection admitted to the PICUs in T\u0026uuml;rkiye between 2020 and 2024, including the COVID-19 pandemic.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eMedical records of 646 children (360 boys, 286 girls, 70% younger than 12 months; 70.6% previously healthy) have been evaluated. Underlying disease was identified in 190 children (29.4%), and congenital heart disease in 58 (9%). Complications included pleural effusion (n\u0026thinsp;=\u0026thinsp;8), pneumothorax (n\u0026thinsp;=\u0026thinsp;8), central nervous system involvement (n\u0026thinsp;=\u0026thinsp;19), apnea (n\u0026thinsp;=\u0026thinsp;10), and myocarditis (n\u0026thinsp;=\u0026thinsp;5). Respiratory co-pathogens were detected in 169 patients (26.2%). During PICU admission, 165 patients (25.5%) required IMV. The mortality rate was 5.4% due to RSV infection. Logistic regression revealed that the presence of an underlying disease significantly increased mortality risk (OR 3.15, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) and this association remained significant in infants under one year (OR 3.57, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eMost children admitted to the PICU due to RSV infection were under one year of age and previously healthy, while mortality was associated with underlying conditions. Monitoring RSV cases in the PICU can be used as a probe for determining the burden of disease and economic cost in the country and for potential treatment and prevention strategies.\u003c/p\u003e","manuscriptTitle":"Burden, Risk Factors, and Outcomes of RSV Infection in Pediatric ICUs Across Türkiye: RSVP Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-23 19:29:16","doi":"10.21203/rs.3.rs-7691297/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"7c3f12dd-7076-4257-9abd-b3891d95c057","owner":[],"postedDate":"October 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-18T13:09:03+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-23 19:29:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7691297","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7691297","identity":"rs-7691297","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}