The coronavirus disease-2019 (COVID-19), caused by severe acute respiratory syndrome virus 2 (SARS-CoV-2), was first detected in December 2019 and rapidly disseminated across the globe [1]. In Japan, the first confirmed case of COVID-19 was documented on January 15, 2020 [2]. Subsequently, COVID-19 spread from metropolitan areas to rural regions [3]. Consequently, COVID-19 cases increased from 0.2 million in 2020 to 1.7 million in 2021 and 29.2 million in 2022. The spread of COVID-19 among Japanese children remained relatively gradual until the emergence of the Omicron variants. This phenomenon can be attributed to COVID-19 predominantly affecting adults during the early phase of the pandemic, coupled with the Japanese government's implementation of infection prevention measures, including universal masking and hand sanitization, in educational institutions, where adherence rates were notably high [4]. Consequently, COVID-19 cases among children <20 years increased from 15 thousand in 2020 to 230 thousand in 2021 and 7 million in 2022.

The COVID-19 pandemic presented formidable challenges to healthcare systems. Understanding how healthcare systems responded to the COVID-19 pandemic is crucial for future pandemic planning and preparedness. However, such data has been limited, particularly within the context of pediatric healthcare setting. A recent nationwide study conducted in Japan revealed that inpatient healthcare systems adapted to the unique demands imposed by the COVID-19 pandemic by implementing the changes in practice patterns from 2020 to 2022 [5]. Nevertheless, how outpatient healthcare systems responded to the COVID-19 pandemic at a national level remains unclear.

Therefore, our study delineated the trends in incidence rates of COVID-19 and investigated the changes in health resource use and clinical practice patterns from January 2020 to May 2022 to understand how the pediatric healthcare system responded to the COVID-19 pandemic at a national level.