What strains should be in this year’s seasonal influenza vaccines?

The European Medicines Agency (EMA) has issued its recommendations for the influenza strains that manufacturers should include in their vaccines for the prevention of seasonal flu strains this year.

Manufacturers of egg-based or live attenuated trivalent vaccines for the 2021/2022 season should include these three virus strains:

• an A/Victoria/2570/2019 (H1N1)pdm09-like virus;
• an A/Cambodia/e0826360/2020 (H3N2)-like virus;
• a B/Washington/02/2019 (B/Victoria lineage)-like virus

Manufacturers of cell-based trivalent vaccines for the 2021/2022 season should include these three virus strains:

• an A/Wisconsin/588/2019 (H1N1)pdm09-like virus;
• an A/Cambodia/e0826360/2020 (H3N2)-like virus;
• a B/Washington/02/2019 (B/Victoria lineage)-like virus

For quadrivalent vaccines with two influenza B viruses, a B/Phuket/3073/2013-like virus should be added to the strains mentioned above.

These recommendations apply to the manufacture of both inactivated and live attenuated influenza vaccines.

To make the recommendations, the EMA Committee for Medicinal Products for Human Use (CHMP)’s Ad hoc Influenza Working Group of the Biologics Working Party (BWP) considered information on international surveillance by World Health Organization (WHO) and Research on Influenza at the UK’s Francis Crick Institute. The recommendations agree with those of the WHO.

The EMA recommends that marketing authorisation holders submit applications to change the composition of centrally authorised seasonal flu vaccines by 14 June 2021.