EU Recommendations for the Seasonal Influenza Vaccine Composition for the Season 2021/2022

messages in brief | 10/05/2021

The EMA adopted the new recommendations for the composition of seasonal influenza vaccines for the season 2021/2022 (published 30 March 2021)

Influenza viruses can be fatal (, but preventive vaccination is a suggestive option.

The recommendations for the seasonal influenza vaccine composition have to be re-evaluated each year since influenza viruses are subject to a considerable antigenic variability and new viruses emerge.

Each year in March, European experts (Biologics Working Party Adhoc Influenza Working Group of the Human Medicines Committee (CHMP)) decide on the new composition based on recommendations published by the WHO. The timely recommendation allows manufacturers and regulators sufficient time to ensure availability of vaccines prior to start of the next influenza season.

The decision on which influenza or vaccine strains should be included in the seasonal influenza vaccines is based on epidemiologic and clinical findings from the Global Influenza Surveillance and Response System (GISRS) network: typically, new viruses emerge in Asia and spread via Europe towards the Americas and the southern hemisphere.

For the purpose of virus surveillance, the GISRS including 147 National Influenza Centres in 123 WHO Member States collected and tested numerous clinical specimens in the last year. Notably, record-low levels of influenza detections have been reported in 2020/21 in contrast to previous seasons, which is in part attributed to the initially reduced influenza surveillance and/or reporting activities in many countries in response to the COVID-19 pandemic. Additionally, COVID-19 mitigation strategies (including restrictions on travel, use of respiratory protection, and social-distancing measures) have contributed to decreased influenza activity


Beyond GISRS data, additional data are considered to ensure that the recommended strains match as closely as possible the strains circulating next season thereby contributing to vaccine effectiveness: serological and genetic characterization studies of recently circulating viruses, virus fitness forecasting, and vaccine effectiveness data.


Taking into account the above information, trivalent vaccines in season 2021/2022 should contain

Egg-based Vaccines

  • 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.

Cell-based Vaccines

  • 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.

Quadrivalent vaccines should contain in addition

  • a B/Phuket/3073/2013-like strain (B/Yamagata/16/88 lineage)


Compared to the previous season 2020/2021, the above recommendation differs with respect to the recommendation for influenza A (H1N1)pdm09 and influenza A (H3N2) viruses. Since the same strains are not optimal for both production in egg-based and cell-based production systems, different viruses are recommended for the influenza A(H1N1) components. This facilitates timely vaccine production.




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