Seasonal respiratory infections typically surge within a limited time window, but the exact timing within a given year is hard to predict. The disruptions caused by the COVID-19 pandemic led to dramatic changes in the transmission dynamics of many pathogens, providing a unique opportunity to study the determinants and robustness of the seasonal timing of epidemics. Combining detailed data on acute respiratory infections from Germany with an epidemiological model, we analyzed changes in the timing of seasonal epidemics. The seasonal surge in infections occurred substantially earlier during the COVID-19 pandemic, and was reflected in a corresponding shift in the seasonality of all-cause mortality. We show that this is a consistent, but transient outcome of disrupted epidemic seasonality, predictable from basic epidemiological principles.

The authors have declared no competing interest.

This study did not receive any funding.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The study used ONLY openly available epidemiological data from the Robert-Koch-Institut (http://github.com/robert-koch-institut) and openly available mortality data from the Federal Statistics Office of Germany (http://www-genesis.destatis.de).

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

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All data is openly available online from the Robert-Koch-Institut (http://github.com/robert-koch-institut) and from the Federal Statistics Office of Germany (http://www-genesis.destatis.de).