School infection control strategy during and after the COVID-19 pandemic: Nationwide trends (2022-2024)

The coronavirus disease-2019 (COVID-19) pandemic required schools, densely populated settings with diverse age groups, to dynamically adjust infection control strategies in response to evolving public health challenges. Despite substantial documentation of such strategies in healthcare facilities, detailed data from school environments remain limited during and after the COVID-19 pandemic.

A nationwide web-based survey was conducted using a random sample of schools (N = 854) to examine changes in infection control strategies, the implementation of school events, and decision-making influences over fiscal years 2022-2024. To identify longitudinal patterns in preventive behavior, we applied time-series clustering based on dynamic time warping.

Between 2022 and 2024, key mitigation efforts such as compulsory mask usage (from 84.3% to 2.2%) and routine disinfection of shared spaces (from 89.7% to 12.3%) saw a steep decline. Meanwhile, hand hygiene and classroom ventilation remained consistently prioritized. The proportion of schools hosting events without restrictions (e.g., sports days, excursions) increased substantially. Around 50% of schools reported using infection prevention tools not officially recommended. While the proportion of schools implementing 7-10 infection prevention measures decreased from 93.4% in 2022 to 50.2% in 2023, schools with 0-3 measures increased from 16.2% in 2023 to 64.8% in 2024.

This study provides nationwide insights into how Japanese schools adjusted their infection control strategies across three academic years. These findings highlight the need for evidence-informed decision-making and closer partnerships with infectious disease experts to improve preparedness for future public health crises.