WHO Announces 2026-2027 Flu Vaccine Recommendations & Strain Updates
The World Health Organization (WHO) has announced its recommendations for the composition of influenza vaccines for the northern hemisphere influenza season. These recommendations, made following a four-day consultation examining global influenza surveillance data, are crucial for ensuring that vaccines are closely matched to circulating viruses, maximizing their effectiveness in preventing severe illness and death.
Influenza viruses are notorious for their constant evolution, necessitating regular updates to vaccine composition. The WHO’s recommendations serve as a blueprint for national regulatory agencies and pharmaceutical companies worldwide, guiding the development, production, and licensing of influenza vaccines for the upcoming season. This proactive approach is essential in the ongoing effort to mitigate the impact of seasonal influenza.
The WHO’s Global Influenza Surveillance and Response System (GISRS) plays a central role in this process. Twice yearly, experts from WHO Collaborating Centres and Essential Regulatory Laboratories convene to review and analyze data generated by GISRS and its partners. This collaborative effort allows for a comprehensive assessment of circulating influenza strains and informs the selection of vaccine candidates.
“Season after season, constantly evolving influenza viruses circulate globally, showing us how connected our world is. Shared risks require shared action,” stated Dr. Tedros Adhanom Ghebreyesus, WHO Director-General. “WHO’s recommendations for influenza vaccine composition rest on the diligent, year‑round work of the Global Influenza Surveillance and Response System (GISRS) and partners. Thanks to GISRS, next season’s vaccines have been updated to counter the latest strains of influenza viruses, in turn better protecting communities.”
Seasonal Influenza and Emerging Variants
The emergence of a distinct variant of the A(H3N2) virus, classified as J.2.4.1 (also referred to as “subclade K”), significantly influenced this year’s recommendations. This variant spread rapidly across the globe, contributing to an earlier start to the influenza season in many countries and, in some regions, higher-than-usual levels of influenza activity. Subclade K became the dominant influenza virus reported across many regions.
influenza A viruses were predominant, with other variants of A(H3N2) and A(H1N1) also recorded. Levels of influenza B viruses (B/Victoria lineage) remained low, and no cases of B/Yamagata lineage viruses have been recorded since .
Zoonotic Influenza and Pandemic Preparedness
Beyond seasonal influenza, the WHO consultation also addressed the ongoing threat of zoonotic influenza – influenza viruses that originate in animals and have the potential to infect humans. These viruses are a significant concern due to their pandemic potential.
Since , , 25 human infections with zoonotic influenza viruses were reported to the WHO from six countries. The majority of these cases involved exposure to infected animals or contaminated environments, with no evidence of human-to-human transmission. However, continued surveillance is critical.
The biannual meetings of the GISRS include a detailed assessment of these zoonotic viruses and the selection of new candidate vaccine viruses (CVVs). These CVVs can be rapidly used to manufacture vaccines should a pandemic threat arise. At the recent meeting, experts recommended the development of a new CVV for an A(H9N2) virus.
2026-2027 Influenza Vaccine Recommendations
Based on these analyses, the WHO recommends the following for the northern hemisphere influenza season:
Egg-Based Vaccines
- An A/Missouri/11/2025 (H1N1)pdm09-like virus
- An A/Darwin/1454/2025 (H3N2)-like virus
- 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
- A B/Pennsylvania/14/2025 (B/Victoria lineage)-like virus
Seasonal influenza is an acute respiratory infection caused by influenza viruses, affecting people worldwide. The WHO estimates around one billion cases annually, resulting in 3–5 million severe illnesses and an estimated 290,000 to 650,000 respiratory deaths each year. The ongoing work of the GISRS, established in , remains vital in tracking and responding to this global health challenge.