By Bunmi Yekini
The World Health Organization (WHO) has unveiled its recommendations for the viral composition of influenza vaccines for the 2025–2026 northern hemisphere flu season. The announcement was made at the conclusion of a four-day meeting on the Composition of Influenza Virus Vaccines, a biannual consultation aimed at keeping flu vaccines effective against evolving virus strains.
According to WHO, the influenza virus is constantly changing, and the vaccines must adapt accordingly, while the recommendations are based on extensive global surveillance data and expert analysis to ensure optimal protection.
The WHO’s advisory group, comprising experts from WHO Collaborating Centres and Essential Regulatory Laboratories, analyzed data from the Global Influenza Surveillance and Response System (GISRS) to determine the most prevalent and concerning strains.
For the upcoming flu season, WHO recommends that trivalent (three-strain) influenza vaccines include the following:
Egg-based vaccines:
- A/Victoria/4897/2022 (H1N1)pdm09-like virus
- A/Croatia/10136RV/2023 (H3N2)-like virus
- B/Austria/1359417/2021 (B/Victoria lineage)-like virus
Cell culture-, recombinant protein-, or nucleic acid-based vaccines:
- A/Wisconsin/67/2022 (H1N1)pdm09-like virus
- A/District of Columbia/27/2023 (H3N2)-like virus
- B/Austria/1359417/2021 (B/Victoria lineage)-like virus
For quadrivalent (four-strain) vaccines, the WHO reaffirmed its previous recommendation to include:
- B/Phuket/3073/2013 (B/Yamagata lineage)-like virus
WHO says updates are crucial to ensuring vaccines remain effective and protect the global population from severe flu outbreaks – a leading virologist involved in the consultation.
The WHO’s recommendations serve as a guide for national regulatory agencies and pharmaceutical companies to develop and distribute influenza vaccines ahead of the 2025–2026 flu season. Public health officials urge individuals, particularly high-risk groups, to get vaccinated to reduce the burden of seasonal influenza.