Hospital Burden and Characteristics of Pediatric COVID-19 Based on a Multi-Center Collaborative Retrospective Study in Japan

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant emergence preceded a large number of pediatric coronavirus disease 2019 (COVID-19) cases, putting considerable strain on hospitals across Japan. We evaluated the pediatric disease burden of COVID-19 in pediatric hospitals.Methods: This retrospective study evaluated all pediatric patients (defined as aged <21 years) hospitalized with SARS-CoV-2 infection or as close contacts, at four children’s hospitals, between January 1, 2022, and May 31, 2022. Clinical characteristics, reasons for admission, and outcome data were analyzed. Findings:A total of 492 patients (median age, 3·0 years; male, 58·7%) were included during the study period. Of these, 232 (47·2%) patients had at least one underlying disease. Asymptomatic and mild diseases were common during the study period (n=451; 91·7%). Social reasons (including a lack of family support at home) for hospitalization accounted for 36·8% (n=181) inpatients. The median length of stay was 4·0 days. Fever was the most common symptom (n=273, 55·5%), followed by upper respiratory (n=77, 15·7%) and neurological symptoms (n=60, 12·2%). Overall, 34 (6·9%) children required invasive mechanical ventilation, 51 (10·4%) were admitted to the pediatric intensive care unit, and two (0·4%) died. COVID-19 vaccination rate was low (n=14/200, 7·0%).Interpretation: The disease burden during the Omicron-predominant period was attributable to asymptomatic and mild infections, and some patients were hospitalized for social reasons. To maintain a medical care system for critically ill patients, each medical facility must play a role according to its function.Funding Information: No funding was secured for this study.Declaration of Interests: The authors declare no conflicts of interest.Ethics Approval Statement: This study was approved by our institutional review board at Hyogo prefectural Kobe Children's Hospital (no. R4-63). Informed consent was obtained from parents using the opt-out method.