Background: Responding to the COVID-19 pandemic, kindergarten through 12 th grade schools implemented non-pharmaceutical interventions (NPIs). The effects of school-based NPIs on broader community levels of acute respiratory infection (ARI) have not been defined. We utilized an existing longitudinal cohort of households reporting weekly ARI cases to evaluate effects of evolving school districtwide NPIs on ARI activity at eight transition points from December 2019 through October 2022. Methods: Household ARI data was reported through GROVES (the GReat ORCHARDS Vaccine Effectiveness Study—a prospective cohort study based in the OSD). Participating GROVES families completed weekly online surveys with respiratory illness updates. Mixed effects logistic regression was used to examine the association between eight school-related transition events during the COVID-19 pandemic and changes in trajectory of ARI risk for GROVES family members, while accounting for family clusters. Transition events were assessed using a ±4-week window of community data. Results: Opening schools with maximal NPIs (mandated masking and physical distancing, with hybrid education) was not associated with increased community ARI activity. The four transition events associated with significant ARI risk trajectory increases included summer breaks (June 2020, p=0.001; June 2021, p=0.002), and the start of school with mandatory masking only (September 2021, p<0.001) or without NPIs (September 2022, p<0.001). Conclusions: School-based NPI implementation was associated with reduced risks for community ARI activity. Enhanced surveillance platforms such as the weekly online surveys used in this study are valuable tools for better understanding and monitoring SARS-CoV-2 and respiratory virus transmission in schools and surrounding communities.

Background School-aged children and school reopening dates have important roles in community influenza transmission. Although many studies evaluated the impact of reactive closures during seasonal and pandemic influenza outbreaks on medically attended influenza in surrounding communities, few assess the impact of planned breaks (i.e., school holidays) which coincide with influenza seasons, while accounting for differences in seasonal peak timing. Here, we analyze the effects of winter and spring breaks on influenza risk in school-aged children, measured by student absenteeism due to influenza-like illness (a-ILI). Methods We compared a-ILI counts in the two-week periods before and after each winter and spring break over five consecutive years in a single school district. We introduced a “pseudo-break” of 9 days’ duration between winter and spring break each year when school was still in session to serve as a control. The same analysis was applied to each pseudo-break to support any findings of true impact. Results We found strong associations between winter and spring breaks and a reduction in influenza risk, with a nearly 50% reduction in a-ILI counts post-break compared to the period before break, and the greatest impact when break coincided with increased local influenza activity. Conclusions These findings suggest that brief breaks of in-person schooling, such as planned breaks lasting 9-16 calendar days, can effectively reduce influenza in schools and community spread. Additional analyses investigating the impact of well-timed shorter breaks on a-ILI may determine an optimal duration for brief school closures to effectively suppress community transmission of influenza.