EMA has issued an 
update of the EU recommendations for the influenza virus strains that vaccine manufacturers should include in vaccines for the prevention of seasonal influenza from autumn 2021.
The recommendations now also contain a decision on suitable H1N1 and H3N2 viruses for seasonal live attenuated influenza vaccines. The list of reagents for vaccine standardisation has also been updated. Details such as the specific virus strains to be included, are available in the updated 2021/2022 recommendations issued by EMA’s Biologics Working Party (BWP) ad-hoc Influenza Working Group.
The initial EU strain recommendations for the composition of 2021–2022 seasonal influenza vaccines were made on 25 March 2021.
Every year, the ad-hoc Influenza Working Group issues EU guidance regarding the composition of seasonal influenza vaccines on the basis of recommendations made by the World Health Organization (WHO).