WHO Recommendations for 2026–2027 Northern Hemisphere Influenza Vaccine Composition

The World Health Organization (WHO) reported its recommended viral composition for 2026–2027 northern hemisphere seasonal influenza vaccines after a 4-day consultation reviewing global influenza surveillance data.

The announcement describes platform-specific strain selections and summarizes recent virus circulation considered during the meeting. WHO frames the recommendations as a periodic output of its vaccine composition consultations held for each hemisphere. Overall, the release outlines which viruses are recommended for inclusion and what surveillance patterns were noted alongside those selections.

WHO presents recommended components separately for egg-based vaccines and for cell culture–, recombinant protein–, or nucleic acid–based vaccines. The A(H1N1)pdm09-like component is aligned across platforms (A/Missouri/11/2025-like), while the A(H3N2)-like component (A/Darwin/1454/2025-like for egg-based vs A/Darwin/1415/2025-like for non-egg platforms) and the B/Victoria lineage component (B/Tokyo/EIS13-175/2025-like for egg-based vs B/Pennsylvania/14/2025-like for non-egg platforms) differ by platform.

For egg-based vaccines, WHO lists: 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. For cell culture–, recombinant protein–, or nucleic acid–based vaccines, WHO lists: 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. In this presentation, the stated difference between platform types is the selected A(H3N2)-like and B/Victoria-lineage-like strain designations, while the A(H1N1)pdm09-like component is the same; WHO notes these recommendations are used by national vaccine regulatory agencies and pharmaceutical companies to develop, produce, and license influenza vaccines.

Surveillance notes in the release focus on changes in A(H3N2) viruses during 2025 and on how activity unfolded across regions. WHO reports that a notably different A(H3N2) variant emerged in August 2025, classified as J.2.4.1 and also referred to as “subclade K,” and that it spread rapidly across the globe. The release links this pattern with an earlier start to the influenza season in many countries and describes several countries as reporting higher-than-usual levels of activity. Across regions, WHO describes influenza A viruses as predominant overall, with other variants of A(H3N2) and A(H1N1) also recorded. In contrast, WHO reports low detection of influenza B viruses (B/Victoria lineage) and states that no B/Yamagata lineage viruses have been recorded since March 2020, positioning these circulation patterns as part of the consultation’s context.

The consultation also reviewed zoonotic influenza events and candidate vaccine virus (CVV) considerations alongside seasonal vaccine composition. WHO reports that since 23 September 2025 (following the prior consultation), 25 human infections with zoonotic influenza were reported to WHO from six countries, and that no human-to-human transmission was reported. The release adds that most cases involved exposure to infected animals or environments contaminated with influenza viruses. In its summary of meeting outcomes, WHO states that experts recommended development of a new CVV for an A(H9N2) virus.

Overall, the announcement describes a single agenda spanning seasonal strain recommendations and monitoring and preparation activities related to zoonotic influenza.

Key Takeaways:

• WHO reported 2026–2027 northern hemisphere vaccine composition recommendations that distinguish egg-based from non-egg platform strain designations, with differences described for the A(H3N2)-like and B/Victoria-lineage-like components and the same A(H1N1)pdm09-like component across platforms.
• WHO’s surveillance summary described emergence of A(H3N2) J.2.4.1 (“subclade K”) in August 2025 with rapid spread and an earlier season start, overall predominance of influenza A viruses, low detection of B/Victoria lineage viruses, and no recorded B/Yamagata lineage viruses since March 2020.
• WHO reported 25 human zoonotic influenza infections from six countries since 23 September 2025 with no reported human-to-human transmission, and stated that experts recommended developing a new A(H9N2) candidate vaccine virus as part of the consultation’s outputs.