The World Health Organization (WHO) today announced its recommendations for the viral composition of influenza (or ‘flu’) vaccines for use in the 2027 southern hemisphere influenza season. The announcement was made following an international consultation on the composition of influenza virus vaccines.
Seasonal influenza causes substantial illness and many hospitalizations each year. Regular updates to vaccine composition are needed because influenza viruses continually evolve. WHO’s recommendations are used by national vaccine regulatory agencies and pharmaceutical companies around the world to develop, produce, and license influenza vaccines for the following influenza season. This ensures that vaccines are closely matched to the viruses expected to circulate, offering the best possible protection against severe illness and death.
Twice each year, WHO convenes experts from its Collaborating Centres and Essential Regulatory Laboratories to review surveillance data generated through the Global Influenza Surveillance and Response System (GISRS) and other sources, and recommend vaccine compositions for upcoming influenza seasons.
"For nearly 75 years, the WHO Global Influenza Surveillance and Response System has demonstrated the power of global solidarity in public health," said Dr Maria Van Kerhove, WHO's Director for Epidemic and Pandemic Management. "The commitment of countries and laboratories to share data, viruses and expertise enables WHO to make timely vaccine recommendations, strengthening our collective ability to detect and respond to emerging influenza threats. This is global public health collaboration at its best."
From February to August 2026, influenza A(H1N1)pdm09, A(H3N2) and influenza B viruses circulated in varying proportions across all regions of the world, causing disease. Influenza A viruses were the most common in most regions, except Northern and Western Africa, North America and Eastern Asia, where influenza B viruses dominated.
WHO recommends that vaccines for use in the 2027 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.
These biannual meetings include a detailed assessment of these viruses and the selection of new candidate vaccine viruses (CVVs) from contemporary zoonotic influenza viruses, which can be used rapidly to manufacture vaccines should a pandemic threat arise. Information on newly selected zoonotic influenza CVVs is available on the WHO website.
About WHO
Dedicated to the well-being of all people and guided by science, WHO leads and champions global efforts to give everyone, everywhere, an equal chance at a safe and healthy life. We are the United Nations’ agency for health that connects nations, partners and people in more than 150 locations – leading the world’s response to health emergencies, preventing disease, addressing the root causes of health issues and expanding access to medicines and health care. Our mission is to support all countries to promote, provide and protect health. “Together for health. Stand with science”, the theme of World Health Day 2026, marks a year-long campaign to highlight science as the foundation for protecting health and well-being worldwide.