Injected trivalent inactivated influenza vaccines are most commonly used throughout the world. Influenza antigen preparation varies between manufacturers.
Risks of an adverse event following influenza vaccination are far less common than complications related to influenza itself, and the adverse events are generally localised and mild.
Genetic and antigenic characterization data generated at the Worldwide Influenza Centre for viruses with collection dates after 31 January 2023 until 31 August 2023 informed the WHO influenza vaccine composition meeting (VCM) in September 2023 when recommendations were made for the southern hemisphere (SH) 2024 influenza season.
This issue of the ECDC Communicable Disease Threats Report (CDTR) the period 28 January - 3 February 2024 and includes updates on SARS-CoV-2 variant classification, swine influenza, human cases of co-infection with seasonal influenza and avian influenza, influenza, western equine encephalitis, and an overview of respiratory virus epidemiology in the EU/EEA.