FDA Approves Moderna’s mFLUSIVA, First mRNA Flu Vaccine, for Adults 50 and Over

Correction — August 8, 2026: An earlier version of this article stated that Moderna’s vaccine met non-inferiority standards and produced strong antibody responses across all influenza strains. Both were wrong: the Phase III trial demonstrated superiority over a standard-dose comparator, and immunogenicity exceeded the comparator on influenza A strains only. It also described Sanofi as an active mRNA flu competitor; Sanofi has discontinued that program. This article has been rewritten.

The U.S. Food and Drug Administration approved mFLUSIVA (mRNA-1010) on August 5, 2026, making Moderna’s seasonal influenza shot the first mRNA vaccine licensed for flu. The label covers adults 50 and over only, and the portion covering adults 65 and over was granted under accelerated approval, contingent on a postmarketing study running across two influenza seasons.

The approval closes a regulatory sequence that began with a rejection. The FDA initially issued a refusal to file on Moderna’s application — declining to review it at all — before reversing and clearing the vaccine. BioIntel covered that refusal in February, when it read as a setback for mRNA beyond COVID-19. It now reads as the first move in a review that ended in licensure.

The efficacy data

The pivotal P304 Phase III trial enrolled more than 40,000 participants across 11 countries with a median follow-up of roughly six months. Against a licensed standard-dose comparator, mFLUSIVA showed a relative vaccine efficacy of 26.6% in adults 50 and over, rising to 27.4% in adults 65 and over. Laboratory-confirmed influenza occurred in 2.0% of mFLUSIVA recipients against 2.8% of standard-dose recipients.

Relative vaccine efficacy is the figure that matters for reading this correctly: it measures the reduction in illness against another vaccine, not against no vaccine at all. The absolute difference in the trial was 0.8 percentage points.

By strain, efficacy was 29.6% against H1N1, 22.2% against H3N2, and 29.1% against B/Victoria. On immunogenicity, mFLUSIVA exceeded comparator antibody titers on the influenza A strains and was similar on the B strains — a distinction that a generic “broad protection” framing erases, and one that matters because H3N2, the strain with the weakest showing here, is historically the driver of severe seasons in older adults.

The label is the commercial story

An approval capped at 50 and over is a materially smaller market than the universal-recommendation flu franchise it competes into. The accelerated-approval mechanism in 65 and over adds a second constraint: the indication in the highest-risk, highest-value population is provisional, and confirmatory data across two seasons will decide whether it holds.

The larger gate is not the FDA at all. The CDC’s Advisory Committee on Immunization Practices has not issued a recommendation, and ACIP is what drives payer coverage, pharmacy stocking, and provider ordering in the U.S. influenza market. Approval permits sale; recommendation creates demand. Until ACIP acts, mFLUSIVA has a license and no established route into routine seasonal use.

The competitive picture has already resolved

Coverage of a first-in-class approval tends to ask who files next. In mRNA influenza, that question has been answered, and not in Moderna’s favor.

Pfizer already holds Phase 3 data at 34.5% relative efficacy against Fluzone — a stronger number than Moderna’s 26.6%, on a comparator in the same class. Cross-trial comparisons are not head-to-head evidence, and different trials enroll different populations in different seasons, but a competitor arriving with a better headline figure changes what “first approval” is worth.

Sanofi has publicly scrapped its mRNA seasonal influenza program. The incumbent with the largest installed flu franchise has decided the modality is not where it will defend that position — a judgment about commercial return, not about whether the science works.

So the read is narrower than it first appears. Moderna is first to a license in a category where a rival has better data and the largest incumbent has walked away. Being first matters most if it converts into an ACIP recommendation and stocking decisions before Pfizer arrives.

What the approval unlocks

The clearance has consequences inside Moderna’s own pipeline. It establishes a licensed mRNA influenza component, which is the prerequisite for the company’s combination influenza/COVID-19 vaccine, and it clears a path for resubmission of the combination and pandemic influenza programs that had been held up. Filings have also been accepted in the European Union, Canada, and Australia, so the label question will be tested by regulators working from the same dataset under different standards — and whether they replicate the 50-and-over cap is the clearest available signal of how conservative the FDA’s read was.

What to watch

• ACIP. A recommendation, its age scope, and whether it preferentially positions mFLUSIVA against standard-dose shots. This is the commercial gate.
• The postmarketing study in 65 and over. Two influenza seasons of confirmatory data. Failure converts an accelerated approval into a withdrawn indication.
• Pfizer’s filing. Whether a 34.5% figure translates into a broader label than Moderna’s, which would make first approval a temporary advantage rather than a durable one.
• The EU, Canadian, and Australian decisions. Whether the 50-and-over restriction is a global read of the data or an FDA-specific one.
• H3N2 in the field. Trial efficacy of 22.2% against the strain that drives severe seasons is the number most likely to be tested by real-world use.