Seasonal influenza 2021−2022 - Annual Epidemiological Report

Surveillance report
Publication series: Annual Epidemiological Report on Communicable Diseases in Europe

European Centre for Disease Prevention and Control. Seasonal influenza 2021-2022. In: ECDC. Annual epidemiological report for 2021. Stockholm: ECDC; 2022.

The 2021−2022 influenza season in the EU/EEA marked the return of influenza virus activity after a low-level circulation following the onset of the COVID-19 pandemic. Despite increased influenza activity in 2021−2022 compared to the 2020−2021 season, the circulation and timing were not comparable with any annual influenza epidemic activity observed before the COVID-19 pandemic or after the 2009 influenza pandemic.

The seasonal pattern showed an unprecedented late onset, crossing the epidemic threshold in week 08/2022, with an overall shorter duration compared to all seasons since 2009. The overall low and late onset of influenza virus circulation during the 2021−2022 season might have been influenced by the COVID-19 pandemic and measures implemented in the countries during the winter period, leading to late activity when measures were lifted.

As Member States move towards integrating surveillance of SARS-CoV-2, influenza and other relevant respiratory viruses, underlying systems may change and in the future reported data may not be comparable with historical data.