In Europe, epidemics of highly pathogenic avian influenza (HPAI) used to be a seasonal phenomenon associated with migratory waterfowl that were returning to their overwintering sites in the autumn.Since 2020, however, this picture has changed. HPAI viruses, particularly of the influenza A(H5) subtype, have caused the worst epidemics in birds observed to date, with more than 14,000 reported outbreaks and culling of roughly 96 million farmed birds in Europe.