FDA Advisers Back 2027 Flu Vaccine Strains, 9-0

Q: Which strains did the committee recommend?

For egg-based trivalent vaccines: an A/Missouri/11/2025 (H1N1)pdm09-like strain, an A/Darwin/1454/2025 (H3N2)-like strain, and a B/Tokyo/EIS13-175/2025 (B/Victoria lineage)-like strain. For cell-culture or recombinant vaccines: A/Missouri/11/2025 (H1N1)pdm09-like, A/Darwin/1415/2025 (H3N2)-like, and B/Pennsylvania/14/2025 (B/Victoria lineage)-like. Both formulas are trivalent, with no B/Yamagata-lineage component.

Q: Why did the committee describe this as an easy decision?

Because the recommended strains are effectively unchanged from the ones VRBPAC picked earlier in 2026 for the US Northern Hemisphere 2026-27 season. A committee member, Arnold Monto, said the decision was straightforward because little had shifted in circulating virus characteristics since that earlier selection.

Q: Does VRBPAC's recommendation bind FDA or manufacturers?

VRBPAC advises; it does not itself set the strain composition. FDA typically follows its advisory committee's strain recommendation when authorizing the season's vaccines, and manufacturers use the recommendation to begin formulating Southern Hemisphere product. The World Health Organization separately issues its own recommendation for the global Southern Hemisphere formula, which regulators outside the US also draw on.

FDA Advisers Back 2027 Flu Vaccine Strains, 9-0

FDA’s Vaccines and Related Biological Products Advisory Committee voted unanimously on 1 October to recommend the virus strains for egg-based and cell-culture/recombinant Southern Hemisphere influenza vaccines for the 2027 season — carrying forward, largely unchanged, the strains it picked for this year’s Northern Hemisphere formula.

Connor GriggsFounder & Editor-in-ChiefOctober 2, 2026 (5 min read)

FDA’s Vaccines and Related Biological Products Advisory Committee voted 9-0 on 1 October 2026 to recommend the virus strains for the 2027 Southern Hemisphere influenza season, a routine but closely watched procedural step that sets the formula US and allied manufacturers will begin producing against for next year’s flu season below the equator. The vote carried forward, largely unchanged, the strains the same committee recommended earlier this year for the US Northern Hemisphere 2026-27 vaccines.

What the committee recommended

Influenza vaccine strain selection happens twice a year because the virus drifts and because the Northern and Southern Hemispheres run offset flu seasons: VRBPAC recommends a formula for the US Northern Hemisphere season around February or March, and again for the Southern Hemisphere season each September or October, roughly aligning with the World Health Organization's own twice-yearly recommendation process for the global vaccine supply. The 1 October meeting was the latter: a recommendation aimed at manufacturers supplying the Southern Hemisphere's 2027 season, which runs opposite the US winter.

The committee recommended two related but distinct formulas. For egg-based trivalent vaccines — still the dominant production method — it recommended an A/Missouri/11/2025 (H1N1)pdm09-like strain, an A/Darwin/1454/2025 (H3N2)-like strain, and a B/Tokyo/EIS13-175/2025 (B/Victoria lineage)-like strain. For cell-culture-based and recombinant vaccines, which use a different production process and sometimes carry slightly different strain designations for the same subtype, it recommended A/Missouri/11/2025 (H1N1)pdm09-like, A/Darwin/1415/2025 (H3N2)-like, and B/Pennsylvania/14/2025 (B/Victoria lineage)-like. Neither formula includes a B/Yamagata-lineage component; US flu vaccines have been trivalent rather than quadrivalent since the Yamagata lineage effectively disappeared from circulation in recent years.

Why the vote was uncontroversial

The 9-0 tally reflects what the committee itself described as an easy call. The strains it recommended for the 2027 Southern Hemisphere season are effectively the same ones it recommended earlier in 2026 for the US Northern Hemisphere 2026-27 formula — meaning circulating influenza viruses have not drifted far enough from the current vaccine strains, in the committee's assessment, to warrant a change. Committee member Arnold Monto was reported characterizing the decision as straightforward for exactly that reason: little had changed in the virus's genetic and antigenic profile since the committee's last strain selection.

What happens next

VRBPAC's recommendation is advisory; FDA is not bound by it, though the agency has historically followed its advisory committee's strain picks when authorizing each season's vaccines. Manufacturers use the recommendation as the signal to begin formulating and testing Southern Hemisphere product on the timeline needed to have vaccine available before that hemisphere's flu season begins. The World Health Organization runs a parallel, separate recommendation process for the global Southern Hemisphere formula that other countries' regulators draw on; the two processes have converged on compatible strains in past seasons, though they are not formally linked.

Frequently asked questions

What did VRBPAC vote on, and when?

FDA's Vaccines and Related Biological Products Advisory Committee met 1 October 2026 and voted 9-0 to recommend virus strain composition for egg-based and cell-culture/recombinant influenza vaccines for the 2027 Southern Hemisphere season.

Which strains did the committee recommend?

Egg-based trivalent: A/Missouri/11/2025 (H1N1)pdm09-like, A/Darwin/1454/2025 (H3N2)-like, B/Tokyo/EIS13-175/2025 (B/Victoria)-like. Cell-culture/recombinant: A/Missouri/11/2025 (H1N1)pdm09-like, A/Darwin/1415/2025 (H3N2)-like, B/Pennsylvania/14/2025 (B/Victoria)-like.

Why did the committee describe this as an easy decision?

The recommended strains are effectively unchanged from VRBPAC's earlier 2026 pick for the US Northern Hemisphere 2026-27 season, reflecting limited drift in circulating viruses since that selection.

Does VRBPAC's recommendation bind FDA or manufacturers?

No. VRBPAC advises; FDA has historically followed its strain recommendation when authorizing each season's vaccines, and manufacturers use it to begin formulation.

Sources & further reading

Citeline Pink Sheet, “US FDA Panel Unanimously Backs Flu Vaccine Strains For 2027 Southern Hemisphere,” 1 October 2026. insights.citeline.com
World Health Organization, “Recommended composition of influenza virus vaccines for use in the 2027 southern hemisphere influenza season.” who.int
Associated Press, “US FDA advisers recommend flu vaccine strains for 2027 Southern Hemisphere season,” 1 October 2026 (syndicated). staradvertiser.com

Regulatory News reports on public regulatory documents. It is not legal advice, and the primary sources above govern. If we have made an error, we will say so in public: see corrections.