The Food and Drug Administration has approved Moderna’s influenza vaccine, to be marketed as mFlusiva, the first licensed seasonal flu shot manufactured using mRNA technology. The decision makes this Moderna’s fourth vaccine to enter the U.S. market. Moderna indicated it expects some doses to be available before the upcoming flu season.
The vaccine’s regulatory path included a high-profile dispute earlier in 2026. In February, Vinay Prasad, then the FDA’s director of biologics, issued a rare “refusal-to-file” notice to Moderna, stating the agency would not review the application based on the data package provided. Moderna publicly disclosed the agency’s position and its own objections, and within about a week the agency reversed that decision. The official who issued the refusal-to-file left the FDA at the end of April.
The FDA granted a standard approval for use of mFlusiva in adults ages 50 to 64, and an accelerated approval for adults 65 and older. For the accelerated approval in the older age group, Moderna committed to conducting a Phase 4 post-licensure trial to generate additional effectiveness data, particularly comparing mFlusiva with high-dose or adjuvanted vaccines that are preferentially recommended for older adults in the U.S.
At a June meeting of the Vaccines and Related Biological Products Advisory Committee (VRBPAC), regulators and external advisers reviewed Phase 3 results. For adults aged 50 to 64, participants who received Moderna’s mRNA vaccine were reported to be 27% less likely to have test-confirmed influenza than those who received a standard-dose comparator. The committee voted unanimously that the vaccine’s benefits outweighed its risks.
A central point of contention during review was Moderna’s choice of comparator in the older adult cohort. U.S. recommendations favor adjuvanted or high-dose influenza vaccines for older adults. The FDA had raised the comparator issue with Moderna before the trial began; company documents indicate the FDA discussed it but did not categorize it as an absolute impediment at that time. Moderna also argued that some of the 11 countries participating in the Phase 3 trial do not routinely use adjuvanted or high-dose vaccines for older adults, which influenced trial design and comparator selection.
The article highlights manufacturing and strategic advantages of the mRNA platform compared with conventional egg- or cell-based influenza vaccine production. Traditional methods require months of lead time and rely on World Health Organization strain selection well ahead of the season; by contrast, mRNA vaccines can be produced more rapidly. This faster manufacturing could enable strain updates closer to the flu season and could be advantageous in the event of a pandemic, potentially speeding licensure pathways for a pandemic vaccine if one were needed.
For its accelerated approval in adults 65 and older, Moderna agreed to perform a Phase 4 trial to collect additional real-world effectiveness data and to compare performance with U.S.-preferred older-adult vaccines. Separately, Moderna has submitted the vaccine for regulatory review outside the U.S.; the product has been accepted for review in the European Union, Canada, and Australia, and further submissions are planned later in the year.
Overall safety profiles between the mRNA vaccine and comparators were described as similar. However, the mRNA vaccine arm reported substantially more side effects, most of which were mild and lasted one to two days. The increased reactogenicity was a notable finding discussed by advisers and regulators during the review process.
Moderna’s chief executive, Stéphane Bancel, issued a statement noting that influenza remains a significant public health challenge and that mFlusiva offers an important new option for older Americans. He also emphasized the broader potential of the company’s mRNA platform to address public health needs through scientific innovation. Moderna said it expects initial vaccine doses to be available ahead of the coming flu season.