Regional and facility-type variations in infectious diseases in childcare and early childhood education facilities in Japan during the COVID-19 pandemic: A nationwide cross-sectional questionnaire survey.

Young children are susceptible to infectious diseases due to their developing immune systems and close contact in group care settings. During the coronavirus disease 2019 (COVID-19) pandemic, infection prevention measures may have altered the epidemiology of common childhood infections, yet evidence on variations by facility type and region remains limited. In this study, the occurrence of COVID-19 and child-specific infectious diseases in childcare and early childhood education facilities in Japan was examined with particular focus on facility type and regional population density. A nationwide mail survey was conducted between January and April 2023 among 5,000 facility managers, and 710 valid responses were analysed. Over 90% of facilities reported at least one COVID-19 case within the previous year. The occurrence of child-specific infectious diseases, including adenovirus infection, hand, foot, and mouth disease, herpangina, streptococcal infection, norovirus infection, and respiratory syncytial virus infection, was lower in kindergartens serving children aged ≥ 3 years than in children in daycare centres or certified childcare centres (p < 0.05). Hand, foot, and mouth disease and influenza virus infection showed significant linear associations with population density, with lower reporting rates in less densely populated regions (p < 0.05). Conversely, rotavirus infection was more frequently reported in low-density regions (p < 0.05), whereas other child-specific infectious diseases exhibited heterogeneous and non-linear regional patterns, indicating that population density alone does not explain regional variation. These results highlight the importance of facility-, age-, and region-specific approaches to infection prevention in childcare settings beyond the COVID-19 pandemic.