WHO Announces 2026-2027 Flu Vaccine Composition

The World Health Organization (WHO) has announced recommendations for the composition of influenza vaccines for the 2026-2027 northern hemisphere influenza season, following a four-day consultation examining global influenza surveillance data. Seasonal influenza, a contagious respiratory infection, causes an estimated 650,000 respiratory deaths worldwide annually, highlighting the importance of timely vaccine updates for public health preparedness .

Global Surveillance and Viral Evolution

The recommendations stem from the perform of the WHO’s Global Influenza Surveillance and Response System (GISRS), a global platform that monitors influenza activity and viral evolution throughout the year. This ongoing surveillance allows clinicians and vaccine developers to adjust vaccine formulations in anticipation of each influenza season .

Key Viral Strain: A(H3N2) Variant

This year’s update is largely driven by the global spread of a new A(H3N2) variant, classified as J.2.4.1, also referred to as “subclade K.” This variant emerged in August 2025 and contributed to early and intense influenza activity in several countries . Influenza A viruses were dominant with limited detections of influenza B, and no confirmed cases of B/Yamagata since early 2020 .

Zoonotic Influenza Monitoring

Experts also continue to monitor zoonotic influenza viruses, which pose a pandemic threat. Since September 2025, 25 human cases linked to animal exposure or contaminated environments have been reported across six countries. No human-to-human transmission has been identified. The panel recommended developing a new candidate vaccine virus targeting A(H9N2) in preparation for potential future threats .

2026-2027 Vaccine Recommendations

The WHO recommends the following for the 2026-2027 northern hemisphere influenza season:

• 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 .

Implications for Public Health

These updated recommendations underscore the importance of influenza vaccination, particularly for high-risk groups, to prevent severe illness, hospitalization, and death. The annual updates ensure vaccines are closely matched to circulating strains, maximizing protection and supporting global efforts to mitigate the impact of influenza .