Moderna's mRNA Flu Vaccine Faces FDA Advisory Panel Review

Moderna's MFLUSIVA (mRNA-1010), the first mRNA-based seasonal influenza vaccine candidate in the U.S., went before the FDA's VRBPAC advisory panel on June 18, 2026, with [MRNA](/stocks/MRNA) shares surging roughly 11-12% on favorable pre-meeting briefing documents.

The FDA's Vaccines and Related Biological Products Advisory Committee (VRBPAC) convened June 18, 2026, to assess the benefit-risk profile of MFLUSIVA (mRNA-1010), Moderna's investigational trivalent mRNA seasonal influenza vaccine. If approved, MFLUSIVA would become the first mRNA-based flu vaccine authorized in the United States, a milestone that would validate the platform's reach well beyond COVID-19.

MRNA shares surged roughly 11-12% ahead of the meeting after the FDA released pre-meeting briefing documents citing no major deficiencies in Moderna's application. The rally was concentrated on June 16-17 when those documents went public, not on the day of the panel vote itself. The FDA's formal approval decision is scheduled for August 5, 2026. The road to this point was turbulent: in February 2026, the FDA issued a Refusal to File letter, with CBER director Vinay Prasad arguing Moderna had not benchmarked against a high-dose flu vaccine for older adults. The agency reversed course days later after Moderna restructured its regulatory strategy, seeking traditional approval for adults 50-64 based on clinical efficacy and accelerated approval for adults 65 and older based on immunogenicity data, with a Phase IV confirmatory trial required for the older cohort.

Phase 3 data from Study P304 (40,805 participants) showed MFLUSIVA delivered 26.6% relative vaccine efficacy against RT-PCR-confirmed influenza-like illness versus a standard-dose flu vaccine, rising to 47.9% when measured against hard healthcare outcomes including ER visits, hospitalizations, and urgent care. FDA reviewers flagged residual concerns: data covering only a single flu season, uncertainty around efficacy against the B/Victoria strain, and the absence of data in immunocompromised or very frail elderly individuals. The broader regulatory backdrop is unusually charged: Health Secretary RFK Jr. has taken a skeptical stance toward mRNA vaccines, and a federal court in March 2026 blocked his overhaul of childhood vaccine advisory committees. A VRBPAC vote to recommend approval would be a significant counterweight to that policy friction, though the final FDA decision remains independent of the panel's outcome.