Background

Mixed evidence regarding school breaks requires analyzing their role in infection spread and protecting high-risk groups.

Objectives

The aim of the study is to quantify the epidemiological impact of planned school breaks, including school year onset and staggered winter holidays, on age-stratified respiratory infection patterns.

Material and methods

Data on 292 million respiratory visits (ICD-10: J00-J22) from 2010–2019 were obtained from the Polish National Healthcare Fund. The Savitzky-Golay filter was used to calculate differences in the autumn infection peak timing among age groups. The impact of alternating the timing of winter holidays among provinces interrupting the influenza season was calculated using SARIMAX and subsequently pooled using linear regression.

Results

Disaggregation of the population into age groups revealed varied effects. The autumn infection wave first affected primary school children and then spread to the entire population, starting with the adjacent groups. While the influenza season’s peak timing showed no clear age differences, a two-week winter holiday quickly reduced infections among school-age children. The effect on the elderly was modest and delayed by a month. This effect was weaker in regions with larger households. In the initial weeks, there was slight evidence of increased contact with younger siblings or grandparents.

Conclusions

While school-age children significantly drive infection spread, the effectiveness of school breaks in protecting elders is likely overstated, as age-stratified social interactions must be considered. Moreover, such interruptions have a transient effect and are followed by a rebound.