Michael Coston
Editor, Senior Moderator
WHO Recommendations for Influenza Vaccine Composition for the 2026-2027 Northern Hemisphere Influenza Season
Credit ACIP
#19,068
Twice each year international influenza experts meet to discuss recent developments in human and animal influenza viruses around the world, and to decide on the composition of the next influenza season’s flu vaccine.
Due to the time it takes to manufacture and distribute a vaccine, decisions on which strains to include must be made at least six months in advance.
As occasionally happens, that can provide a window of opportunity for `drifted' or mutated flu strains to emerge, and spread globally (see last Nov's Increasing Concerns Over A `Drifted' H3N2 Virus This Flu Season).
Earlier this week, in Preprint: Near Real-time Data on the Human Neutralizing Antibody Landscape to Influenza Virus as of Early 2026 to Inform Vaccine-strain Selection, we looked at a `near real-time' assessment of the human neutralizing antibody landscape against currently circulating influenza A viruses.
A review which found that most people have low antibody defenses against recently emerged H3N2 subclade K and H1N1 D.3.1.1 viruses.
Today the WHO released their recommendations for the composition of this fall's 2026-2027 Northern Hemisphere flu vaccine, which recommends updates for all 3 flu strains; H1N1, H3N2, and Influenza B.
Overview
For vaccines for use in the 2026-2027 northern hemisphere influenza season, WHO recommends 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.
The 2026 Southern Hemisphere vaccine already has the recommended updated H1N1 component, but retains older strains against H3N2 and Influenza B. Despite this apparent mismatch, it will still likely provide important protection against severe disease.
Sadly, seasonal flu vaccine uptake in the United States peaked in 2019, and has begun a slow, but steady decline since.
But the more we learn about influenzas' extrapulmonary impacts on the body (see Risk of Cardiovascular Events After Influenza: A Population-based Self Controlled Case Series Study), the more important protecting yourself becomes.
Which is why I consider the flu vaccine to be an important part of my `flu prevention' strategy each year (along with masking, handwashing, and avoiding indoor crowds).
While none of this guarantees I'll continue to go unscathed, my last bout with `flu' was in the summer of 2009 (after attending a pandemic flu conference!), and I've only contracted COVID once, before the first vaccine was released.
Since my strategy seems to work, I see no reason to `fix' it.
https://afludiary.blogspot.com/2026/02/who-recommendations-for-influenza.html
Credit ACIP
#19,068
Twice each year international influenza experts meet to discuss recent developments in human and animal influenza viruses around the world, and to decide on the composition of the next influenza season’s flu vaccine.
Due to the time it takes to manufacture and distribute a vaccine, decisions on which strains to include must be made at least six months in advance.
As occasionally happens, that can provide a window of opportunity for `drifted' or mutated flu strains to emerge, and spread globally (see last Nov's Increasing Concerns Over A `Drifted' H3N2 Virus This Flu Season).
Earlier this week, in Preprint: Near Real-time Data on the Human Neutralizing Antibody Landscape to Influenza Virus as of Early 2026 to Inform Vaccine-strain Selection, we looked at a `near real-time' assessment of the human neutralizing antibody landscape against currently circulating influenza A viruses.
A review which found that most people have low antibody defenses against recently emerged H3N2 subclade K and H1N1 D.3.1.1 viruses.
Today the WHO released their recommendations for the composition of this fall's 2026-2027 Northern Hemisphere flu vaccine, which recommends updates for all 3 flu strains; H1N1, H3N2, and Influenza B.
Overview
For vaccines for use in the 2026-2027 northern hemisphere influenza season, WHO recommends 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.
The 2026 Southern Hemisphere vaccine already has the recommended updated H1N1 component, but retains older strains against H3N2 and Influenza B. Despite this apparent mismatch, it will still likely provide important protection against severe disease.
Sadly, seasonal flu vaccine uptake in the United States peaked in 2019, and has begun a slow, but steady decline since.
Pandemic fatigue, plus growing anti-vaccination sentiment, and admittedly `hit-or-miss' protection against influenza infection have all had an impact.
But the more we learn about influenzas' extrapulmonary impacts on the body (see Risk of Cardiovascular Events After Influenza: A Population-based Self Controlled Case Series Study), the more important protecting yourself becomes.
Which is why I consider the flu vaccine to be an important part of my `flu prevention' strategy each year (along with masking, handwashing, and avoiding indoor crowds).
While none of this guarantees I'll continue to go unscathed, my last bout with `flu' was in the summer of 2009 (after attending a pandemic flu conference!), and I've only contracted COVID once, before the first vaccine was released.
Since my strategy seems to work, I see no reason to `fix' it.
https://afludiary.blogspot.com/2026/02/who-recommendations-for-influenza.html