Summer School Holidays and the Growth Rate in Sars-CoV-2 Infections Across German Districts

How significant are school holidays for the Covid-19 crisis? In this ecological study, we analyse the association between summer school holidays and the weekly growth rate in SARS-CoV-2 infections in 401 German districts. In Germany school holidays are coordinated between states and spread out in order to reduce the number and length of traffic jams on motorways. We employ a district fixed effects Chow-type structural break model specification in which we test whether the holiday season as well as the period of two weeks after holidays end result in a statistically significantly higher infection growth rate than the period of two weeks before holidays start, our presumed counterfactual. We also allow the effect to vary week-by-week and by states. We find that between 30 and 50 percent of the growth rate in new infections in Germany can be attributed to the holiday season. A significant increase in the growth of new infections begins approximately four weeks after holidays begin - that is, shortly after the first wave of holiday-makers return. The effect becomes stronger the further holidays proceed and does not revert back to normal in the two weeks after the end of holidays. States in the West of Germany tend to experience stronger effects than those in the East. Part of this finding is explained by another result, namely that we find significant interaction effects of school holidays with per capita taxable income and the share of foreign residents in a districts population.