FDA Advisory Panel Votes 9-0 in Favor of Moderna's mRNA Flu Vaccine, Setting Stage for August Decision

Federal advisers have thrown unanimous support behind Moderna's investigational mRNA-based influenza vaccine, completing a dramatic turnaround for a product that was rejected for review by the same agency earlier this year.

The FDA's Vaccines and Related Biological Products Advisory Committee (VRBPAC) voted 9-0 that the benefits of mFLUSIVA (mRNA-1010) outweigh its risks for adults aged 50 to 64, and voted separately 9-0 that the same benefit-risk conclusion applied to adults aged 65 and older.¹ The FDA, which is not bound by advisory panel recommendations but typically follows them, has set a PDUFA goal date of August 5, 2026 for its final decision.¹ Moderna is seeking standard approval in the younger age group and accelerated approval for adults 65 and older, with a postmarketing confirmatory trial required for the latter.

What did the panel say?

Panelists acknowledged several evidentiary limitations raised in FDA staff briefing documents ahead of the meeting but found they did not outweigh the case for the vaccine. Chief among the concerns were efficacy data drawn from a single flu season, limited confirmed cases against influenza B/Victoria, and a relatively short post-vaccination follow-up window.²

"We did miss an opportunity to really understand the performance of the product pre-licensure," said Hana El Sahly, MD, professor of molecular virology and microbiology at Baylor College of Medicine, referencing the trial's abbreviated timeline. The 2024–2025 flu season was more severe than anticipated, allowing the Phase 3 P304 trial to surpass its 836-case accrual target — reaching 968 cases — well ahead of schedule, which reduced the overall observation period.²

Despite those limitations, panelists ultimately found the data compelling. "The studies that were presented today were very well conducted," said Flor Munoz-Rivas, MD, associate professor of pediatrics and infectious disease at Baylor College of Medicine. "They have very clear results that are very robust." She added that approval would leave the United States "better prepared for emerging strains or pandemic strains in the future."²

Stanley Perlman, MD, PhD, a pediatric disease expert at the University of Iowa, offered a similarly affirmative assessment. "The data were very convincing," he said. "Putting it all together, the benefits outweigh the problems."²

What evidence supported the vote?

The VRBPAC vote was anchored by results from the Phase 3 P304 trial, published in the New England Journal of Medicine, which showed mFLUSIVA reduced the likelihood of RT-PCR–confirmed influenza-like illness by 26.6% relative to a standard-dose seasonal comparator.³ When measured against healthcare outcomes including emergency department visits, hospitalizations, and urgent care, relative vaccine efficacy rose to 47.9%.³

Moderna also presented immunogenicity data from a Phase 3 study in adults 65 and older comparing mFLUSIVA against Fluzone High-Dose, showing superior antibody responses at Day 29 and at six months — data that underpinned the accelerated approval pathway for that age group.¹

On safety, no serious signals emerged at the meeting. Panelists noted that reactogenicity events consistent with mRNA vaccines — including fatigue, joint pain, and muscle aches — were recorded at higher rates than comparators, and emphasized that communication around the vaccine's side effect profile would be important for uptake given public skepticism around mRNA technology following the COVID-19 pandemic.²

"There's benefits and risks, and we do believe the benefits outweigh the risks," said Rituparna Das, Moderna's head of infectious and rare disease clinical development. "But the communication is quite important."²

What happens next?

The unanimous vote advances mFLUSIVA toward a final FDA approval decision by August 5, 2026 — a timeline that would allow it to be available for the 2026–2027 influenza season if approved. The confirmatory postmarketing study agreed upon for the 65-and-older population is expected to enroll up to 800,000 participants across two flu seasons, with the aim of filling the evidentiary gaps panelists identified.²

If approved, mFLUSIVA would become the first mRNA-based seasonal influenza vaccine licensed in the US. Regulatory submissions are also under active review in the EU, Canada, and Australia.¹

The vote caps an unusual regulatory episode that began in February 2026, when then-CBER director Vinay Prasad, MD, MPH, issued a rare refusal-to-file letter citing Moderna's use of a standard-dose rather than high-dose comparator in its pivotal trial. The FDA reversed that decision within days following public backlash and a formal Type A meeting. Both Prasad and former FDA commissioner Marty Makary — who had enacted stricter vaccine review standards — have since departed the agency, and interim leadership has appeared to signal a shift toward more traditional regulatory posture.²

References

1. Moderna announces FDA advisory committee votes unanimously in favor of the benefit-risk profile of mRNA-1010, an investigational seasonal influenza vaccine. (2026 Jun 18). Moderna, Inc. https://finance.yahoo.com/healthcare/articles/moderna-announces-fda-advisory-committee-200000554.html
2. Alvarado D. (2026 Jun 18). Moderna flu vaccine wins unanimous support from FDA panel. BioPharma Dive. https://www.biopharmadive.com/news/moderna-mflusiva-mrna-flu-vaccine-fda-committee-vote/823275/
3. Leroux-Roels I, Huang G, Ferguson M, et al; (2026 May 6). Efficacy and safety of an mRNA seasonal influenza vaccine in adults. N Engl J Med. https://www.nejm.org/doi/full/10.1056/NEJMoa2516491
4. Vaccines and Related Biological Products Advisory Committee June 18, 2026 Meeting Announcement. (2026 Jun 3). U.S. Food and Drug Administration. https://www.fda.gov/advisory-committees/advisory-committee-calendar/vaccines-and-related-biological-products-advisory-committee-june-18-2026-meeting-announcement
5. Schoenthaler E. (2026 Jun 18). FDA advisory panel convenes today to weigh Moderna's mRNA-based flu vaccine. BioPharm International. https://www.biopharminternational.com/view/fda-advisory-panel-convenes-today-to-weigh-moderna-s-mrna-based-flu-vaccine