Hospitalization and Symptoms of Children and Adolescents with COVID-19 in Finland: A Retrospective Registry-based Study

Hospitalization and Symptoms of Children and Adolescents with COVID-19 in Finland: A Retrospective Registry-based 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 Hospitalization and Symptoms of Children and Adolescents with COVID-19 in Finland: A Retrospective Registry-based Study Alexa Myöhänen, Paula Tähtinen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7753302/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 COVID-19 is a respiratory tract infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Pediatric COVID-19 infections are typically mild compared to adults and the prognosis is often good. Our main purpose was to study the need for hospitalization due to COVID-19 among children and adolescents in Finland. We also gathered information on the symptoms during COVID-19 infection. Methods This was a retrospective registry-based study. We analyzed data from children under 16 years of age who tested positive for SARS-CoV-2 during visits to the Emergency Room at the Department of Paediatrics and Adolescent Medicine, Turku University Hospital, between January 29, 2020, and May 31, 2022. We collected information from patient records on the symptoms, their duration, the need for hospitalization and the length of hospital stays. Results During our study, 127 565 SARS-CoV-2 PCR-tests were performed for children under 16 years of age, of which 7% (9 193/127 565) were positive. The hospitalization rate was 1% (99/9 193), and the need for intensive care was 0.2% (14/9 193). The median length of hospital stay was one day (range from 1 to 14 days). Fever was the most common symptom, occurring in 79% (173/220) of children. Respiratory symptoms were also common. Gastrointestinal symptoms were more infrequent. Conclusion The need for hospitalization, particularly intensive care, was low among children with COVID-19. Respiratory symptoms were common, with fever being the most frequently reported symptom. children COVID-19 infection SARS-CoV-2 hospitalization symptoms Figures Figure 1 Figure 2 INTRODUCTION AND BACKGROUND COVID-19 is a respiratory tract infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which originated in Wuhan, China, in December 2019. Since then, the COVID-19 pandemic has spread globally, with far-reaching impacts on both public health and economics. [ 1 , 2 ] In Finland, the first case of COVID-19 was diagnosed on January 1, 2020, in Lapland Central Hospital [ 3 ]. The first death caused by SARS-CoV-2 was subsequently confirmed on March 20, 2020 [ 4 ]. The incidence of COVID-19 cases peaked in early 2022, with the majority of infections occurring among young and middle-aged adults [ 5 ]. Pediatric COVID-19 infections are typically mild compared to adults. Children usually have fewer symptoms and a greater prevalence of asymptomatic cases. [ 6 , 7 ] Comorbidities are also less common in children, resulting in a relatively low rate of hospitalization [ 2 , 6 , 8 ]. Overall, the prognosis for children with COVID-19 infection is often good [ 2 , 8 ]. However, investigating the impact of the COVID-19 pandemic on children remains essential for informing preparedness for potential future pandemics. Our aim was to study the need of hospitalization among children and adolescents under 16 years of age due to COVID-19 in The Wellbeing Services County of Southwest Finland. We also collected data on the symptoms of children with COVID-19 infection. METHODS Study Design This was a retrospective registry-based study. All children and adolescents aged 0–16 years who were tested for SARS-CoV-2 in The Wellbeing Services County of Southwest Finland, between January 29, 2020, and May 31, 2022, were included in the study. Children who had a confirmed SARS-CoV-2 infection by a PCR-test (a polymerase chain reaction test) or a rapid antigen test were included for further medical record evaluation. The symptoms of COVID-19 and the need for hospitalization were evaluated in all children who visited the Emergency Room at the Department of Paediatrics and Adolescent Medicine, Turku University Hospital during the study period. We conducted a register search based on specific ICD-10 (International Classification of Diseases 10th Revision) codes. Children who had any of the following diagnostic codes were included in the study: U07.1 = COVID-19 (virus identified), U07.2 = COVID-19 (virus not identified), U08.9 = Personal history of COVID-19, U09.9 = Post COVID-19 condition, B34.2 = Coronavirus infection (unspecified), B97.2 = Coronavirus as the cause of diseases classified elsewhere and Z03.89 = Encounter for observation for other suspected diseases and conditions ruled out. Using patient charts, we collected information on the symptoms, their duration before the emergency room visits, the need for hospitalization, and the length of hospital stay. All cases were de-identified before analysis to ensure anonymity. The study protocol was approved by the Research Services of The Wellbeing Services County of Southwest Finland. According to the Finnish Medical Research Act, ethics approval and informed consent were not required for this retrospective study. The study was conducted in accordance with the Declaration of Helsinki. Statistical Analysis We used the IBM SPSS Statistics software (version 29.0.0.0) for statistical analysis. Categorical variables such as background information, symptom presence and information on hospitalization were presented as frequencies and percentages, while continuous variables, such as patient age and the duration of symptoms and hospitalization were presented as medians and ranges. RESULTS During our study period, 127 565 SARS-CoV-2 PCR-tests were performed in children and adolescents aged 0–16 years in The Wellbeing Services County of Southwest Finland. Of these, 9 193 (7%) were confirmed positive (Fig. 1 ). The first pediatric SARS-CoV-2 positive case was confirmed in March 2020. The number of positive cases was low until January 2022 (Fig. 2 ). Our medical records register search consisted of 228 children who visited the Emergency Room at the Department of Paediatrics and Adolescent Medicine, Turku University Hospital due to COVID-19. Three children were excluded from this study because the ICD-10 codes used were incorrect and SARS-CoV-2 infection was not confirmed by approved tests specified in the methods section. Five children tested positive for COVID-19 by PCR, but they were asymptomatic. Thus, 220 of 9 913 (2%) children with COVID-19 infection were symptomatic and included in the further analysis in our study (Fig. 1 ). Of the symptomatic children, 99 (45%) were hospitalized due to COVID-19 and 14 (6%) needed intensive care (Table 1 ). In addition, two children needed hospital care for another reason while having a concurrent COVID-19 infection (Table 1 ). The median duration of the hospital stay was one day (range from 1 to 14 days). Thus, the need for hospitalization due to COVID-19 was 1% (99/9 193) in The Wellbeing Services County of Southwest Finland. Likewise, the need for intensive care was 0.2% (14/9 193) (Fig. 1 ). The median age of our study sample was 0.93 years (range from 0.01 to 15.76 years) (Table 1 ). The largest age group was 0–3 months (68/220, 31%). Overall, two thirds of the children were under the age of 3 years. There were 101 (46%) females and 119 (54%) males. Majority of the children (119/220, 54%) were from Turku. Other hometowns were much more infrequent and they are summarized in a group called “others” (101/220, 46%). Fever was the most common symptom presenting in 79% (173/220) of the symptomatic children with COVID-19 (Table 2 ). In most cases (81/220, 37%), body temperature was between 38.0–38.9°C at its highest. The median duration of fever before the emergency room visit was one day (range from 1.00 to 8.00 days). Other common symptoms were dyspnea (84/220, 38%), cough (82/220, 37%) and nasal symptoms (77/220, 35%), such as stuffy nose and rhinorrhea. Compared to respiratory symptoms, gastrointestinal symptoms, such as abdominal pain (19/220, 9%), vomiting (38/220, 17%), diarrhea (27/220, 12%) and constipation (3/220, 1%) were less frequent. The median duration of the gastrointestinal symptoms before the emergency room visit was longer than respiratory symptoms. On average constipation lasted three and a half days (range from 3.00 to 4.00 days), diarrhea two days (range from 1.00 to 7.00 days), vomiting one day (range from 1.00 to 7.00 days) and abdominal pain one day (range from 1.00 to 7.00 days). Median duration of respiratory symptoms was from one to one and a half days (range from 1.00 to 13.00 days). Table 2 Occurrence and duration of symptoms in children with COVID-19 before the emergency room visit Symptoms n (%) N = 220 Median duration before the emergency room visit (range) Fever < 38°C, no fever 38.0–38.9°C 39.0–39.9°C 40.0°C or higher Temperature unknown 173 (79) 47 (21) 81 (37) 43 (20) 13 (6) 36 (16) 1.00 (1.00 to 8.00) Dyspnea 84 (38) 1.00 (1.00 to 13.00) Cough 82 (37) 1.00 (1.00 to 13.00) Nasal symptoms 77 (35) 1.50 (1.00 to 13.00) Fatigue 73 (33) 1.00 (1.00 to 7.00) Irritability 70 (32) 1.00 (1.00 to 8.00) Mucosal changes 42 (19) 1.00 (1.00 to 4.00) Vomiting 38 (17) 1.00 (1.00 to 7.00) Rash 29 (13) 1.00 (1.00 to 1.00) Diarrhea 27 (12) 2.00 (1.00 to 7.00) Abdominal pain 19 (9) 1.00 (1.00 to 7.00) Ear pain 18 (8) 1.00 (1.00 to 4.00) Headache 17 (8) 1.00 (1.00 to 7.00) Sore throat 16 (7) 2.50 (1.00 to 9.00) Lymphadenopathy 13 (6) 1.00 (1.00 to 3.00) Sneezing 8 (4) 1.00 (1.00 to 3.00) Constipation 3 (1) 3.50 (3.00 to 4.00) Dizziness 3 (1) 1.50 (1.00 to 2.00) Muscle pain 3 (1) 1.00 (1.00 to 7.00) Conjunctivitis 0 (0) 0.00 (0.00 to 0.00) Swelling of extremities 0 (0) 0.00 (0.00 to 0.00) DISCUSSION Our results show that a significant number of SARS-CoV-2 PCR-tests were taken from children and adolescents between January 2020 and May 2022. However, a very small proportion of the tests were positive and an even smaller proportion of those with SARS-CoV-2 infection ever needed to visit the emergency room during the infection. Our study suggests that the need for hospitalization and especially intensive care was infrequent among children with COVID-19 infection. Thus, most of the cases of COVID-19 among children were mild. Previous studies have shown similar results. A Chinese study categorized 48% of the cases in children as mild, 44% as moderate and 8% as severe or critical [ 9 ]. In another Chinese study, most of the pediatric COVID-19 cases showed mild to moderate clinical features, with only a few being more severe [ 2 ]. In previous studies, the need for hospitalization varied widely from 5% to 62% depending on the study sample, but mostly it was quite rare [ 8 , 10 , 11 , 12 ]. Fever was the most common symptom in our study, occurring in 79% (173/220) of children with COVID-19. This view was supported by the results from several previous studies, where fever was reported in 64–90% of children [ 2 , 7 , 9 , 13 ]. We also found out that gastrointestinal symptoms were less common than respiratory symptoms in children with COVID-19. Similar findings have been reported in a study from Switzerland, where respiratory symptoms were present in 64% of children while gastrointestinal symptoms were observed in 28% of children [ 13 ]. In a Chinese study, most of the children presented with respiratory symptoms, including cough (79%), runny nose (32%) and nasal congestion (18%), whereas gastrointestinal symptoms such as nausea (16%) and diarrhea (11%) were less frequently reported [ 9 ]. Thus, cough was slightly more common in the Chinese study compared to ours, but other respiratory symptoms and gastrointestinal symptoms were equally common in both studies. Most of the children in our study were aged 0–3 months. In Finland, current guidelines recommend that infants less than three months of age with fever should be evaluated by a physician without delay. In contrast, older children and adolescents are more often treated at home during mild infections. This recommendation likely influences the age distribution observed in our study. According to a previous study, fever was more prevalent among neonates and infants compared to older children during COVID-19 [ 13 ]. Therefore, the larger proportion of children aged 0–3 months does not necessarily reflect a higher prevalence of COVID-19 infection within this age group. Strengths and limitations The major limitation of our study is the retrospective study design. We obtained the symptom data from an electronic health record system. Thus, the potential inaccuracies of the data must be acknowledged. However, to minimize these inaccuracies, we conducted a manual review of each case individually rather than relying solely on ICD-10 diagnosis. Our study includes a comprehensive population-based sample from Finland. It covers all children and adolescents under 16 years of age who tested positive for SARS-CoV-2 in The Wellbeing Services County of Southwest Finland during the study period. We collected epidemiologically significant data on COVID-19 in this population, providing information that may be useful in future pandemics. Gathering data on the impact of the COVID-19 pandemic on children remains crucial for public health officials and pandemic preparedness. CONCLUSIONS Our findings suggest that the need for hospitalization, particularly intensive care, during pediatric COVID-19 infection was very low. This indicates that most COVID-19 infections in children were mild. Respiratory symptoms were common, with fever being the most frequently reported symptom. Investigating the impact of the COVID-19 pandemic on children was essential for informing preparedness for potential future pandemics. Abbreviations COVID-19: coronavirus disease 2019 ICD-10: International Classification of Diseases 10 th Revision PCR-test: a polymerase chain reaction test SARS-CoV-2: severe acute respiratory syndrome coronavirus 2 Declarations Ethics approval, consent to participate and consent for publication All cases were de-identified before analysis to ensure anonymity. The study protocol was approved by the Research Services of The Wellbeing Services County of Southwest Finland. According to the Finnish Medical Research Act, ethics approval and informed consent were not required for this retrospective study. The study was conducted in accordance with the Declaration of Helsinki. Availability of data and materials The data generated and analyzed during this study is not publicly available due to individual privacy of the patients included in the study. Competing interests The authors report there are no competing interests to declare. Funding The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Authors´ contributions Conceptualization: Paula A. Tähtinen; Formal analysis: Alexa Myöhänen; Investigation: Alexa Myöhänen; Project administration: Paula A. Tähtinen; Supervision: Paula A. Tähtinen; Writing - original draft: Alexa Myöhänen, Paula A. Tähtinen; Writing - review and editing: Alexa Myöhänen, Paula A. Tähtinen Acknowledgements We would like to thank Miia K. Laine, MD, PhD and Satu Juhannusvuori for providing us the SARS-CoV-2 nasopharyngeal sample data. References Faramarzi A, Norouzi S, Dehdarirad H, Aghlmand S, Yusefzadeh H, Javan-Noughabi J. The global economic burden of COVID-19 disease: a comprehensive systematic review and meta-analysis. Systematic Reviews, BMC. 2024;13(1):68. doi: 10.1186/s13643-024-02476-6. Guo CX, He L, Yin JY, Meng XG, Tan W, Yang GP, Bo T, Liu JP, Lin XJ, Chen X. Epidemiological and clinical features of pediatric COVID-19. BMC Medicine. 2020;18(1):250. doi: 10.1186/s12916-020-01719-2. Finnish Institute for Health and Welfare: News on Coronavirus COVID-19. Matkailijalla todettu koronavirustartunta Lapin keskussairaalassa.January 29, 2020. Available at: www.thl.fi. Accessed: October 24, 2024. Finnish Institute for Health and Welfare: News on Coronavirus COVID-19. Ensimmäinen koronavirustartunnan aiheuttama kuolema Suomessa. March 21, 2020. Available at: www.thl.fi. Accessed: October 24, 2024. Finnish Institute for Health and Welfare: COVID-19 cases in the infectious diseases registry. Available at: www.thl.fi. Accessed: October 24, 2024. Qiu H, Wu J, Hong L, Luo Y, Song Q, Chen D. Clinical and epidemiological features of 36 children with coronavirus disease 2019 (COVID-19) in Zhejiang, China: an observational cohort study. The Lancet Infectious Diseases. 2020;20(6):689–696. doi: 10.1016/S1473-3099(20)30198-5. Yasuhara J, Kuno T, Takagi H, Sumitomo N. Clinical characteristics of COVID-19 in children: a systematic review. Pediatric Pulmonology. 2020;55(10):2565–2575. doi: 10.1002/ppul.24991. Bellino S, Punzo O, Rota MC, Del Manso M, Urdiales AM, Andrianou X, Fabiani M, Boros S, Vescio F, Riccardo F, Bella A, Filia A, Rezza G, Villani A, Pezzotti P. COVID-19 disease severity risk factors for pediatric patients in Italy. Pediatrics. 2020;146(4):e2020009399. doi: 10.1542/peds.2020-009399. Lin F, Chen MT, Zhang L, Xie H, Yang Z, Huang B, Wu JP, Lin WH, Yang LY. Hospitalized children with COVID-19 infection during large outbreak of SARS-CoV-2 Omicron strain: a retrospective study in Chaozhou, Guangdong, China. Annals of Medicine. 2024;56(1):2389301. doi: 10.1080/07853890.2024.2389301. Götzinger F, Santiago-García B, Noguera-Julián A, Lanaspa M, Lancella L, Calò Carducci FI, Gabrovska N, Velizarova S, Prunk P, Osterman V, Krivec U, Lo Vecchio A, Shingadia D, Soriano-Arandes A, Melendo S, Lanari M, Pierantoni L, Wagner N, L'Huillier AG, Heininger U, Ritz N, Bandi S, Krajcar N, Roglić S, Santos M, Christiaens C, Creuven M, Buonsenso D, Welch SB, Bogyi M, Brinkmann F, Tebruegge M. COVID-19 in children and adolescents in Europe: a multinational, multicentre cohort study. The Lancet Child and Adolescent Health. 2020;4(9):653–661. doi: 10.1016/S2352-4642(20)30177-2. Moreira A, Chorath K, Rajasekaran K, Burmeister F, Ahmed M, Moreira A. Demographic predictors of hospitalization and mortality in US children with COVID-19. European Journal of Pediatrics. 2021;180(5):1659–1663. doi: 10.1007/s00431-021-03955-x. Ungar SP, Solomon S, Stachel A, Shust GF, Clouser KN, Bhavsar SM, Lighter J. Hospital and ICU admission risk associated with comorbidities among children with COVID-19 ancestral strains. Clinical Pediatrics. 2023;62(9):1048–1058. doi: 10.1177/00099228221150605. Wurm J, Uka A, Bernet V, Buettcher M, Giannoni E, Kottanattu L, Schöbi N, Zemmouri A, Ritz N, Zimmermann P. The changing clinical presentation of COVID-19 in children during the course of the pandemic. Acta Paediatrica. 2024;113(4):771-777. doi: 10.1111/apa.17061. Table 1 Table 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Table1.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. 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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-7753302","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":534977920,"identity":"7b9ce74a-949f-4eac-8976-a972470e2516","order_by":0,"name":"Alexa Myöhänen","email":"","orcid":"","institution":"Turku University Hospital and University of Turku","correspondingAuthor":false,"prefix":"","firstName":"Alexa","middleName":"","lastName":"Myöhänen","suffix":""},{"id":534977921,"identity":"7b97e395-f308-49d0-8a9b-32039d324a67","order_by":1,"name":"Paula 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1","display":"","copyAsset":false,"role":"figure","size":18204,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart of our study sample\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7753302/v1/4f257b519a7593ba6bbb6a9e.png"},{"id":94623603,"identity":"adb49b9c-4329-4854-bc14-d27857b7bf44","added_by":"auto","created_at":"2025-10-29 04:19:19","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":30356,"visible":true,"origin":"","legend":"\u003cp\u003eSARS-CoV-2 PCR-tests and positive test results of all children and adolescents 0–16 years of age in The Wellbeing Services County of Southwest Finland, between January 29, 2020, and May 31, 2022\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7753302/v1/794b9863a859364d9252e1e6.png"},{"id":95525301,"identity":"15d8fe37-c1e4-4c5c-b2c2-ac5cd506f1bc","added_by":"auto","created_at":"2025-11-10 10:04:45","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":633508,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7753302/v1/cafca87b-268b-4c18-9be5-67ac7753279b.pdf"},{"id":94623452,"identity":"597aebdb-a95f-46bb-8570-664f4b1b6da7","added_by":"auto","created_at":"2025-10-29 04:19:10","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":15115,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.docx","url":"https://assets-eu.researchsquare.com/files/rs-7753302/v1/ace17bff538cab00aeb42593.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Hospitalization and Symptoms of Children and Adolescents with COVID-19 in Finland: A Retrospective Registry-based Study","fulltext":[{"header":"INTRODUCTION AND BACKGROUND","content":"\u003cp\u003eCOVID-19 is a respiratory tract infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which originated in Wuhan, China, in December 2019. Since then, the COVID-19 pandemic has spread globally, with far-reaching impacts on both public health and economics. [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eIn Finland, the first case of COVID-19 was diagnosed on January 1, 2020, in Lapland Central Hospital [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The first death caused by SARS-CoV-2 was subsequently confirmed on March 20, 2020 [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The incidence of COVID-19 cases peaked in early 2022, with the majority of infections occurring among young and middle-aged adults [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e\u003cp\u003ePediatric COVID-19 infections are typically mild compared to adults. Children usually have fewer symptoms and a greater prevalence of asymptomatic cases. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] Comorbidities are also less common in children, resulting in a relatively low rate of hospitalization [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Overall, the prognosis for children with COVID-19 infection is often good [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. However, investigating the impact of the COVID-19 pandemic on children remains essential for informing preparedness for potential future pandemics.\u003c/p\u003e\u003cp\u003eOur aim was to study the need of hospitalization among children and adolescents under 16 years of age due to COVID-19 in The Wellbeing Services County of Southwest Finland. We also collected data on the symptoms of children with COVID-19 infection.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStudy Design\u003c/h2\u003e\u003cp\u003eThis was a retrospective registry-based study. All children and adolescents aged 0\u0026ndash;16 years who were tested for SARS-CoV-2 in The Wellbeing Services County of Southwest Finland, between January 29, 2020, and May 31, 2022, were included in the study. Children who had a confirmed SARS-CoV-2 infection by a PCR-test (a polymerase chain reaction test) or a rapid antigen test were included for further medical record evaluation. The symptoms of COVID-19 and the need for hospitalization were evaluated in all children who visited the Emergency Room at the Department of Paediatrics and Adolescent Medicine, Turku University Hospital during the study period.\u003c/p\u003e\u003cp\u003eWe conducted a register search based on specific ICD-10 (International Classification of Diseases 10th Revision) codes. Children who had any of the following diagnostic codes were included in the study: U07.1\u0026thinsp;=\u0026thinsp;COVID-19 (virus identified), U07.2\u0026thinsp;=\u0026thinsp;COVID-19 (virus not identified), U08.9\u0026thinsp;=\u0026thinsp;Personal history of COVID-19, U09.9\u0026thinsp;=\u0026thinsp;Post COVID-19 condition, B34.2\u0026thinsp;=\u0026thinsp;Coronavirus infection (unspecified), B97.2\u0026thinsp;=\u0026thinsp;Coronavirus as the cause of diseases classified elsewhere and Z03.89\u0026thinsp;=\u0026thinsp;Encounter for observation for other suspected diseases and conditions ruled out. Using patient charts, we collected information on the symptoms, their duration before the emergency room visits, the need for hospitalization, and the length of hospital stay.\u003c/p\u003e\u003cp\u003eAll cases were de-identified before analysis to ensure anonymity. The study protocol was approved by the Research Services of The Wellbeing Services County of Southwest Finland. According to the Finnish Medical Research Act, ethics approval and informed consent were not required for this retrospective study. The study was conducted in accordance with the Declaration of Helsinki.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eWe used the IBM SPSS Statistics software (version 29.0.0.0) for statistical analysis. Categorical variables such as background information, symptom presence and information on hospitalization were presented as frequencies and percentages, while continuous variables, such as patient age and the duration of symptoms and hospitalization were presented as medians and ranges.\u003c/p\u003e\u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eDuring our study period, 127 565 SARS-CoV-2 PCR-tests were performed in children and adolescents aged 0\u0026ndash;16 years in The Wellbeing Services County of Southwest Finland. Of these, 9 193 (7%) were confirmed positive (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). The first pediatric SARS-CoV-2 positive case was confirmed in March 2020. The number of positive cases was low until January 2022 (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eOur medical records register search consisted of 228 children who visited the Emergency Room at the Department of Paediatrics and Adolescent Medicine, Turku University Hospital due to COVID-19. Three children were excluded from this study because the ICD-10 codes used were incorrect and SARS-CoV-2 infection was not confirmed by approved tests specified in the methods section. Five children tested positive for COVID-19 by PCR, but they were asymptomatic. Thus, 220 of 9 913 (2%) children with COVID-19 infection were symptomatic and included in the further analysis in our study (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eOf the symptomatic children, 99 (45%) were hospitalized due to COVID-19 and 14 (6%) needed intensive care (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). In addition, two children needed hospital care for another reason while having a concurrent COVID-19 infection (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). The median duration of the hospital stay was one day (range from 1 to 14 days). Thus, the need for hospitalization due to COVID-19 was 1% (99/9 193) in The Wellbeing Services County of Southwest Finland. Likewise, the need for intensive care was 0.2% (14/9 193) (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe median age of our study sample was 0.93 years (range from 0.01 to 15.76 years) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The largest age group was 0\u0026ndash;3 months (68/220, 31%). Overall, two thirds of the children were under the age of 3 years. There were 101 (46%) females and 119 (54%) males. Majority of the children (119/220, 54%) were from Turku. Other hometowns were much more infrequent and they are summarized in a group called \u0026ldquo;others\u0026rdquo; (101/220, 46%).\u003c/p\u003e\u003cp\u003eFever was the most common symptom presenting in 79% (173/220) of the symptomatic children with COVID-19 (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). In most cases (81/220, 37%), body temperature was between 38.0\u0026ndash;38.9\u0026deg;C at its highest. The median duration of fever before the emergency room visit was one day (range from 1.00 to 8.00 days). Other common symptoms were dyspnea (84/220, 38%), cough (82/220, 37%) and nasal symptoms (77/220, 35%), such as stuffy nose and rhinorrhea. Compared to respiratory symptoms, gastrointestinal symptoms, such as abdominal pain (19/220, 9%), vomiting (38/220, 17%), diarrhea (27/220, 12%) and constipation (3/220, 1%) were less frequent. The median duration of the gastrointestinal symptoms before the emergency room visit was longer than respiratory symptoms. On average constipation lasted three and a half days (range from 3.00 to 4.00 days), diarrhea two days (range from 1.00 to 7.00 days), vomiting one day (range from 1.00 to 7.00 days) and abdominal pain one day (range from 1.00 to 7.00 days). Median duration of respiratory symptoms was from one to one and a half days (range from 1.00 to 13.00 days).\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\u003eOccurrence and duration of symptoms in children with COVID-19 before the emergency room visit\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSymptoms\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003en (%)\u003c/p\u003e\u003cp\u003eN\u0026thinsp;=\u0026thinsp;220\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMedian duration before the emergency room visit (range)\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\u003eFever\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u0026lt;\u0026thinsp;38\u0026deg;C, no fever\u003c/p\u003e\u003cp\u003e38.0\u0026ndash;38.9\u0026deg;C\u003c/p\u003e\u003cp\u003e39.0\u0026ndash;39.9\u0026deg;C\u003c/p\u003e\u003cp\u003e40.0\u0026deg;C or higher\u003c/p\u003e\u003cp\u003eTemperature unknown\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e173 (79)\u003c/p\u003e\u003cp\u003e47 (21)\u003c/p\u003e\u003cp\u003e81 (37)\u003c/p\u003e\u003cp\u003e43 (20)\u003c/p\u003e\u003cp\u003e13 (6)\u003c/p\u003e\u003cp\u003e36 (16)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 8.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eDyspnea\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e84 (38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 13.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCough\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e82 (37)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 13.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNasal symptoms\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e77 (35)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.50 (1.00 to 13.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eFatigue\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e73 (33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 7.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eIrritability\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e70 (32)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 8.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMucosal changes\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e42 (19)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 4.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eVomiting\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e38 (17)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 7.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eRash\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e29 (13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 1.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eDiarrhea\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e27 (12)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.00 (1.00 to 7.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAbdominal pain\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e19 (9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 7.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEar pain\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18 (8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 4.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHeadache\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17 (8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 7.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSore throat\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e16 (7)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.50 (1.00 to 9.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eLymphadenopathy\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13 (6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 3.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSneezing\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8 (4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 3.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eConstipation\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3 (1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.50 (3.00 to 4.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eDizziness\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3 (1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.50 (1.00 to 2.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMuscle pain\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3 (1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.00 (1.00 to 7.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eConjunctivitis\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0 (0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.00 (0.00 to 0.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSwelling of extremities\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0 (0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.00 (0.00 to 0.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eOur results show that a significant number of SARS-CoV-2 PCR-tests were taken from children and adolescents between January 2020 and May 2022. However, a very small proportion of the tests were positive and an even smaller proportion of those with SARS-CoV-2 infection ever needed to visit the emergency room during the infection. Our study suggests that the need for hospitalization and especially intensive care was infrequent among children with COVID-19 infection. Thus, most of the cases of COVID-19 among children were mild. Previous studies have shown similar results. A Chinese study categorized 48% of the cases in children as mild, 44% as moderate and 8% as severe or critical [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. In another Chinese study, most of the pediatric COVID-19 cases showed mild to moderate clinical features, with only a few being more severe [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In previous studies, the need for hospitalization varied widely from 5% to 62% depending on the study sample, but mostly it was quite rare [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eFever was the most common symptom in our study, occurring in 79% (173/220) of children with COVID-19. This view was supported by the results from several previous studies, where fever was reported in 64\u0026ndash;90% of children [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. We also found out that gastrointestinal symptoms were less common than respiratory symptoms in children with COVID-19. Similar findings have been reported in a study from Switzerland, where respiratory symptoms were present in 64% of children while gastrointestinal symptoms were observed in 28% of children [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. In a Chinese study, most of the children presented with respiratory symptoms, including cough (79%), runny nose (32%) and nasal congestion (18%), whereas gastrointestinal symptoms such as nausea (16%) and diarrhea (11%) were less frequently reported [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Thus, cough was slightly more common in the Chinese study compared to ours, but other respiratory symptoms and gastrointestinal symptoms were equally common in both studies.\u003c/p\u003e\u003cp\u003eMost of the children in our study were aged 0\u0026ndash;3 months. In Finland, current guidelines recommend that infants less than three months of age with fever should be evaluated by a physician without delay. In contrast, older children and adolescents are more often treated at home during mild infections. This recommendation likely influences the age distribution observed in our study. According to a previous study, fever was more prevalent among neonates and infants compared to older children during COVID-19 [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Therefore, the larger proportion of children aged 0\u0026ndash;3 months does not necessarily reflect a higher prevalence of COVID-19 infection within this age group.\u003c/p\u003e"},{"header":"Strengths and limitations","content":"\u003cp\u003eThe major limitation of our study is the retrospective study design. We obtained the symptom data from an electronic health record system. Thus, the potential inaccuracies of the data must be acknowledged. However, to minimize these inaccuracies, we conducted a manual review of each case individually rather than relying solely on ICD-10 diagnosis.\u003c/p\u003e\u003cp\u003eOur study includes a comprehensive population-based sample from Finland. It covers all children and adolescents under 16 years of age who tested positive for SARS-CoV-2 in The Wellbeing Services County of Southwest Finland during the study period. We collected epidemiologically significant data on COVID-19 in this population, providing information that may be useful in future pandemics. Gathering data on the impact of the COVID-19 pandemic on children remains crucial for public health officials and pandemic preparedness.\u003c/p\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003eOur findings suggest that the need for hospitalization, particularly intensive care, during pediatric COVID-19 infection was very low. This indicates that most COVID-19 infections in children were mild. Respiratory symptoms were common, with fever being the most frequently reported symptom. Investigating the impact of the COVID-19 pandemic on children was essential for informing preparedness for potential future pandemics.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eCOVID-19: coronavirus disease 2019\u003c/p\u003e\n\u003cp\u003eICD-10: International Classification of Diseases 10\u003csup\u003eth\u003c/sup\u003e Revision\u003c/p\u003e\n\u003cp\u003ePCR-test: a polymerase chain reaction test\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSARS-CoV-2: severe acute respiratory syndrome coronavirus 2\u003c/p\u003e\n"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval, consent to participate and consent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll cases were de-identified before analysis to ensure anonymity. The study protocol was approved by the Research Services of The Wellbeing Services County of Southwest Finland. According to the Finnish Medical Research Act, ethics approval and informed consent were not required for this retrospective study. The study was conducted in accordance with the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data generated and analyzed during this study is not publicly available due to individual privacy of the patients included in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors report there are no competing interests to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026acute; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization: Paula A. T\u0026auml;htinen;\u0026nbsp;Formal analysis: Alexa My\u0026ouml;h\u0026auml;nen; Investigation: Alexa My\u0026ouml;h\u0026auml;nen; Project administration:\u0026nbsp;Paula A. T\u0026auml;htinen;\u0026nbsp;Supervision:\u0026nbsp;Paula A. T\u0026auml;htinen;\u0026nbsp;Writing - original draft: Alexa My\u0026ouml;h\u0026auml;nen,\u0026nbsp;Paula A. T\u0026auml;htinen;\u0026nbsp;Writing - review and editing: Alexa My\u0026ouml;h\u0026auml;nen,\u0026nbsp;Paula A. T\u0026auml;htinen\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to thank Miia K. Laine, MD, PhD and Satu Juhannusvuori for providing us the SARS-CoV-2 nasopharyngeal sample data.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eFaramarzi A, Norouzi S, Dehdarirad H, Aghlmand S, Yusefzadeh H, Javan-Noughabi J. The global economic burden of COVID-19 disease: a comprehensive systematic review and meta-analysis. Systematic Reviews, BMC. 2024;13(1):68. doi: 10.1186/s13643-024-02476-6.\u003c/li\u003e\n \u003cli\u003eGuo CX, He L, Yin JY, Meng XG, Tan W, Yang GP, Bo T, Liu JP, Lin XJ, Chen X. Epidemiological and clinical features of pediatric COVID-19. BMC Medicine. 2020;18(1):250. doi: 10.1186/s12916-020-01719-2.\u003c/li\u003e\n \u003cli\u003eFinnish Institute for Health and Welfare: News on Coronavirus COVID-19. Matkailijalla todettu koronavirustartunta Lapin keskussairaalassa.January 29, 2020. Available at: www.thl.fi. Accessed: October 24, 2024. \u003c/li\u003e\n \u003cli\u003eFinnish Institute for Health and Welfare: News on Coronavirus COVID-19. Ensimmäinen koronavirustartunnan aiheuttama kuolema Suomessa. March 21, 2020. Available at: www.thl.fi. Accessed: October 24, 2024. \u003c/li\u003e\n \u003cli\u003eFinnish Institute for Health and Welfare: COVID-19 cases in the infectious diseases registry. Available at: www.thl.fi. Accessed: October 24, 2024. \u003c/li\u003e\n \u003cli\u003eQiu H, Wu J, Hong L, Luo Y, Song Q, Chen D. Clinical and epidemiological features of 36 children with coronavirus disease 2019 (COVID-19) in Zhejiang, China: an observational cohort study. The Lancet Infectious Diseases. 2020;20(6):689–696. doi: 10.1016/S1473-3099(20)30198-5.\u003c/li\u003e\n \u003cli\u003eYasuhara J, Kuno T, Takagi H, Sumitomo N. Clinical characteristics of COVID-19 in children: a systematic review. Pediatric Pulmonology. 2020;55(10):2565–2575. doi: 10.1002/ppul.24991. \u003c/li\u003e\n \u003cli\u003eBellino S, Punzo O, Rota MC, Del Manso M, Urdiales AM, Andrianou X, Fabiani M, Boros S, Vescio F, Riccardo F, Bella A, Filia A, Rezza G, Villani A, Pezzotti P. COVID-19 disease severity risk factors for pediatric patients in Italy. Pediatrics. 2020;146(4):e2020009399. doi: 10.1542/peds.2020-009399.\u003c/li\u003e\n \u003cli\u003eLin F, Chen MT, Zhang L, Xie H, Yang Z, Huang B, Wu JP, Lin WH, Yang LY. Hospitalized children with COVID-19 infection during large outbreak of SARS-CoV-2 Omicron strain: a retrospective study in Chaozhou, Guangdong, China. Annals of Medicine. 2024;56(1):2389301. doi: 10.1080/07853890.2024.2389301.\u003c/li\u003e\n \u003cli\u003eGötzinger F, Santiago-García B, Noguera-Julián A, Lanaspa M, Lancella L, Calò Carducci FI, Gabrovska N, Velizarova S, Prunk P, Osterman V, Krivec U, Lo Vecchio A, Shingadia D, Soriano-Arandes A, Melendo S, Lanari M, Pierantoni L, Wagner N, L'Huillier AG, Heininger U, Ritz N, Bandi S, Krajcar N, Roglić S, Santos M, Christiaens C, Creuven M, Buonsenso D, Welch SB, Bogyi M, Brinkmann F, Tebruegge M. COVID-19 in children and adolescents in Europe: a multinational, multicentre cohort study. The Lancet Child and Adolescent Health. 2020;4(9):653–661. doi: 10.1016/S2352-4642(20)30177-2.\u003c/li\u003e\n \u003cli\u003eMoreira A, Chorath K, Rajasekaran K, Burmeister F, Ahmed M, Moreira A. Demographic predictors of hospitalization and mortality in US children with COVID-19. European Journal of Pediatrics. 2021;180(5):1659–1663. doi: 10.1007/s00431-021-03955-x.\u003c/li\u003e\n \u003cli\u003eUngar SP, Solomon S, Stachel A, Shust GF, Clouser KN, Bhavsar SM, Lighter J. Hospital and ICU admission risk associated with comorbidities among children with COVID-19 ancestral strains. Clinical Pediatrics. 2023;62(9):1048–1058. doi: 10.1177/00099228221150605.\u003c/li\u003e\n \u003cli\u003eWurm J, Uka A, Bernet V, Buettcher M, Giannoni E, Kottanattu L, Schöbi N, Zemmouri A, Ritz N, Zimmermann P. The changing clinical presentation of COVID-19 in children during the course of the pandemic. Acta Paediatrica. 2024;113(4):771-777. doi: 10.1111/apa.17061.\u003cbr\u003e \u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Table 1","content":"\u003cp\u003eTable 1 is available in the Supplementary Files section.\u003c/p\u003e\n"}],"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":"children, COVID-19 infection, SARS-CoV-2, hospitalization, symptoms","lastPublishedDoi":"10.21203/rs.3.rs-7753302/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7753302/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eCOVID-19 is a respiratory tract infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Pediatric COVID-19 infections are typically mild compared to adults and the prognosis is often good. Our main purpose was to study the need for hospitalization due to COVID-19 among children and adolescents in Finland. We also gathered information on the symptoms during COVID-19 infection.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis was a retrospective registry-based study. We analyzed data from children under 16 years of age who tested positive for SARS-CoV-2 during visits to the Emergency Room at the Department of Paediatrics and Adolescent Medicine, Turku University Hospital, between January 29, 2020, and May 31, 2022. We collected information from patient records on the symptoms, their duration, the need for hospitalization and the length of hospital stays.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eDuring our study, 127 565 SARS-CoV-2 PCR-tests were performed for children under 16 years of age, of which 7% (9 193/127 565) were positive. The hospitalization rate was 1% (99/9 193), and the need for intensive care was 0.2% (14/9 193). The median length of hospital stay was one day (range from 1 to 14 days). Fever was the most common symptom, occurring in 79% (173/220) of children. Respiratory symptoms were also common. Gastrointestinal symptoms were more infrequent.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eThe need for hospitalization, particularly intensive care, was low among children with COVID-19. Respiratory symptoms were common, with fever being the most frequently reported symptom.\u003c/p\u003e","manuscriptTitle":"Hospitalization and Symptoms of Children and Adolescents with COVID-19 in Finland: A Retrospective Registry-based Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-29 04:12:05","doi":"10.21203/rs.3.rs-7753302/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":"d8cba60f-c59f-46be-8d3c-4574f618e4c2","owner":[],"postedDate":"October 29th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-07T05:38:28+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-29 04:12:05","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7753302","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7753302","identity":"rs-7753302","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}