Circulating respiratory viruses, including influenza viruses, SARS-CoV-2 and RSV, all contribute to pressure on healthcare systems during winter in the EU/EEA. In a typical season, influenza causes substantial morbidity in the European population, with up to 50 million symptomatic cases and 15 000 to 70 000 deaths annually. All age groups are affected, although children have higher rates of illness and are usually the first to become sick and transmit the disease in their households, which can drive transmission in the community. It is estimated that up to 20% of the population contract influenza annually. This results in absence from school and work and a significant impact on healthcare systems. A higher impact is seen in closed settings such as long-term care facilities (LTCFs), where outbreaks of seasonal influenza can have high morbidity and mortality.

ECDC decided to assess the risk of influenza for the EU/EEA in the context of early circulation of seasonal influenza in the region and the recently emerged influenza A(H3N2) subclade K that is circulating globally. This is to raise awareness of potential implications and provide recommendations to public health authorities. However, considerable uncertainty remains around the likely public health impact of this subclade on the influenza season.