Nationwide epidemiology and health resource use among children with COVID-19 in Japan

Background: The COVID-19 pandemic posed substantial challenges to healthcare systems. Understanding the responses of pediatric health services is crucial for future pandemic planning and preparedness, yet such data remains limited. Methods: In this retrospective cohort study, we analyzed data from administrative databases developed by Japan Medical Data Center and DeSC Healthcare Inc. The dataset comprised records of 2,612,511 children, totaling 60,224,888 person-months, from January 2020 to May 2022. Multivariate generalized estimation equations were used to examine the incidence rates of COVID-19 and associated health resource use. Results: Our analysis revealed that the incidence rates of COVID-19 gradually increased from Wave I (2.2 cases per 100,000 person-months) to Wave V (177.8cases per 100,000 person-months), with a notable elevation during Wave VI (2367.7 cases per 100,000 person-months). While nucleic acid amplification tests were primarily used during Waves I-V, the use of rapid antigen tests markedly increased in Wave VI. The hospitalization rates increased gradually from 0.2 in Wave I to 10.2 events per 100,000 person-months in Wave VI, and the casehospitalization risk decreased from 14.9% in Wave II to 0.7% in Wave VI. Additionally, we observed decreasing trends in the use of antibiotics (Wave I, 31.8%; Wave VI, 9.0%), whereas antipyretic use rose from Wave I (56.1%) to Wave VI (86.6%). Conclusions: Our study highlighted essential changes in the nationwide pediatric healthcare system's response to the COVID-19 pandemic. These findings provide valuable insights into the future pandemic planning and preparedness.