School closures and respiratory infections transmission and mortality: evidence from school holidays in Poland

This study examines the impact of temporary school closures on influenza transmission and respiratory mortality, leveraging a natural experiment from winter break timings in Polish schools. Using causal inference methods on 12 years of influenza-like illness (ILI) data and 2 decades of respiratory death records, the analysis shows significant reductions in ILI incidence within 4 weeks after closures in an average season: 75% among school-aged children, 55% in adults, 26% in preschool children, and 31% in the elderly, compared to prevacation averages. Notably, a 7% decrease in respiratory mortality was observed among the elderly, highlighting school closures as an effective public health intervention for reducing influenza spread and mortality among high-risk groups.