WHO Updates Influenza Vaccine Recommendations for 2026-2027 Season

The World Health Organization (WHO) has released its recommendations for the composition of influenza vaccines for the upcoming 2026-2027 northern hemisphere season. This decision follows a four-day consultation process where experts reviewed global influenza surveillance data.

To effectively combat the ever-changing nature of influenza viruses, vaccine formulations need to be updated regularly. The WHO's recommendations serve as guidelines for national vaccine regulatory agencies and pharmaceutical companies worldwide, ensuring that the vaccines produced are well matched to the circulating viruses. This alignment is crucial as it helps provide optimal protection against the severe health consequences associated with influenza.

These consultations occur biannually, once for the northern hemisphere and once for the southern hemisphere, bringing together experts from WHO's Collaborating Centres and Essential Regulatory Laboratories that are part of the Global Influenza Surveillance and Response System (GISRS). They analyze data generated by GISRS along with contributions from its partners to inform the vaccine composition.

Dr. Tedros Adhanom Ghebreyesus, the WHO Director-General, emphasized the global interconnectedness highlighted by the influenza viruses. He pointed out that, “Season after season, constantly evolving influenza viruses circulate globally, showing us how connected our world is. Shared risks require shared action.” His statement underscored the importance of the continuous efforts by GISRS and its partners in updating the vaccine compositions to counter the latest strains of influenza, thus enhancing community protection.

The report outlines several findings from the previous influenza season. Notably, in August 2025, a variant of the A(H3N2) virus emerged, designated as J.2.4.1, also known as “subclade K.” This variant spread quickly across various regions, leading to an earlier onset of the influenza season in many places, with higher-than-normal activity reported by several countries. This ‘subclade K’ emerged as the predominant strain, responsible for the majority of reported influenza cases.

While A viruses were found to dominate the influenza landscape, instances of other variants, including A(H1N1), were also noted. Moreover, low levels of influenza B viruses from the B/Victoria lineage were detected, with no reports of B/Yamagata lineage viruses since March 2020.

In addition to seasonal viruses, the consultation assessed zoonotic influenza viruses, which are those that originate in animals but can infect humans. These viruses are a persistent public health concern due to their pandemic potential. Since the last consultation on September 23, 2025, the WHO has documented 25 human infections linked to zoonotic influenza across six countries. The majority of these cases involved exposure to infected animals or environments contaminated with influenza viruses. Importantly, there were no reports of human-to-human transmission of these zoonotic strains.

Such biannual consultations also consider the risk of emergent pandemic strains, with experts selecting candidate vaccine viruses (CVVs) that could be rapidly used to develop vaccines if a pandemic were to occur. At this recent meeting, a new CVV for an A(H9N2) virus was recommended.

For the 2026-2027 northern hemisphere influenza season, WHO specified the following vaccine recommendations:

• For 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.

• For 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.

To conclude, seasonal influenza represents a significant public health challenge worldwide, being a leading cause of respiratory illness and mortality. WHO’s GISRS has been monitoring influenza globally since 1952, making it a crucial element of ongoing public health surveillance.