Composition of Influenza Virus vaccine for the 2027 southern hemisphere

Introduction
The periodic replacement of viruses contained in influenza vaccines is necessary in order for the vaccines to be effective due to the constant evolving nature of influenza viruses, including those circulating and infecting humans.

Twice annually, WHO organizes consultations to analyse influenza virus surveillance data generated by the WHO Global Influenza Surveillance and Response System (GISRS), and issues recommendations on the composition of the influenza vaccines for the following influenza season.

Recommendations
The WHO recommends that trivalent vaccines for use in the 2026 southern hemisphere influenza season contain the following:

Egg-based vaccines:
- an A/Missouri/11/2025 (H1N1)pdm09-like virus;
- an A/Darwin/1454/2025 (H3N2)-like virus; and
- a B/Tokyo/EIS13-175/2025 (B/Victoria lineage)-like virus.

Cell culture-, recombinant protein- or nucleic acid-based vaccines:
- an A/Missouri/11/2025 (H1N1)pdm09-like virus;
- an A/Darwin/1415/2025 (H3N2)-like virus; and
- a B/Pennsylvania/14/2025 (B/Victoria lineage)-like virus.

As part of the review, experts also looked at influenza viruses circulating in animals, particularly those that have caused infections in humans. These animal or zoonotic influenza viruses remain a significant concern because of their potential to cause pandemics.

Source.