Composition of Influenza Virus vaccine for the 2026|2027 northern 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|2027 northern 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. 

No recommendation for the B/Yamagata lineage component of quadrivalent influenza vaccines is given, because all available egg isolates acquired egg-adaptive mutations that remove the potential N-glycosylation site.

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