Impact of COVID-19 pandemic on physical health among children: difference-in-differences analyses of nationwide school health checkup database

Purpose: The COVID-19 pandemic posed tremendous challenges for children, requiring them to adapt to changes in social environments. However, the long-term effects of the pandemic on various aspects of physical health at a national level remain unclear. Methods: In this retrospective cohort study, we analyzed data from nationwide health checkup records among children aged 7–15 years. The dataset comprised 3,544,146 records from 393,794 individuals who graduated from junior high school during fiscal years 2007 to 2022. Difference-indifferences (DID) analyses with multiple time periods were used to examine the impact of COVID-19 on physical health outcomes. Results: Compared with the pre-pandemic period, the COVID-19 pandemic was associated with excess increases in obesity for boys and girls, persisting over the 3 years (DID estimate, +0.42%; 95%CI, 0.23 to 0.61). Also, it was associated with excess increases in underweight (DID estimate, +0.28%; 95%CI, 0.25 to 0.32) and poor visual acuity among boys in the 3 rd year (DID estimate, +1.80%; 95%CI, 1.30 to 2.30]). There were excess reductions in dental caries (DID estimate,-1.48%; 95%CI,-2.01 to-0.95]), glucosuria (DID estimate,-0.55; 95%CI,-0.88 to-0.23), and hematuria (DID estimate,-0.43%; 95%CI,-0.73 to-0.13]) during the 3 rd year of the pandemic. Conclusions: These findings underscore the multifaceted impact of the pandemic on various health indicators for school-aged children. This information could be valuable for public health policy and pediatric healthcare planning in the post-pandemic era.