EU Recommendations for the Seasonal Influenza Vaccine Composition for the Season 2022/2023

messages in brief | 02/05/2022

Currently (April 2022), an increase in influenza activity is observed, which is at least in part attributed to the lifting of COVID-19 mitigation strategies (including restrictions on travel, use of respiratory protection, and social-distancing measures). Compared to previous (pre-pandemic) years, the onset of influenza activity is delayed and has not yet reached epidemic level.

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  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, which is monitoring influenza activity for 70 years : 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 148 National Influenza Centres in 124 WHO Member States collected and tested numerous clinical specimens in the last year.

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, quadrivalent vaccines in season 2022/2023 should contain

Egg-based Vaccines:

  • an A/Victoria/2570/2019 (H1N1)pdm09-like virus
  • an A/Darwin/9/2021 (H3N2)-like virus
  • a B/Austria/1359417/2021 (B/Victoria lineage)-like virus
  • a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus

Cell culture-based vaccines:

  • an A/Wisconsin/588/2019 (H1N1)pdm09-like virus
  • an A/Darwin/6/2021 (H3N2)-like virus
  • a B/Austria/1359417/2021 (B/Victoria lineage)-like virus
  • a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus

Trivalent vaccines should contain the following components: influenza A (H1N1)pdm09, influenza A (H3N2), and influenza B (Victoria lineage).

Compared to the previous season 2021/2022, the above recommendation differs with respect to the recommendation for influenza A (H3N2) and influenza B (Victoria lineage) 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) and influenza A(H3N2) components. This facilitates timely vaccine production.



Further inquiry note