Hospital burden and characteristics of pediatric COVID-19 based on a multicenter collaborative retrospective study in Japan

OBJECTIVES: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant emergence preceded a wave of pediatric coronavirus disease 2019 (COVID-19) cases, putting considerable strain on hospitals across Japan. Our study 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 and May 31, 2022. Clinical characteristics, reasons for admission, and outcome data were analyzed. RESULTS: In total, 492 patients (median age 3.0 years; male 58.7%) were included over 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 for hospitalization (including a lack of family support at home) accounted for 36.8% (n = 181) of 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 (n = 60, 12.2%) symptoms. 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%). CONCLUSIONS: 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.