FDA approves Moderna's mRNA flu vaccine for adults 50 and older

The U.S. Food and Drug Administration has granted approval for Moderna's mFlusiva, an mRNA-based influenza vaccine, for adults aged 50 and older. The agency gave traditional approval to the 50-64 age group and accelerated approval to those 65 and older, pending further data on benefit.

In a randomized trial involving more than 40,000 participants, the mRNA vaccine lowered the incidence of PCR-confirmed influenza illness to about 2.0% of recipients, compared with roughly 2.8% for a licensed standard-dose vaccine, representing a 26.6% relative reduction. Serious cases were also fewer among mFlusiva recipients, though the numbers were too small for a definitive statistical conclusion.

Seasonal flu vaccines traditionally rely on virus grown in chicken eggs, a process that can introduce mismatches between the vaccine strain and circulating viruses. mRNA technology bypasses this step by delivering genetic instructions that prompt the body to produce a viral protein, potentially shortening production time and improving strain matching.

The approval follows concerns about the annual need to predict dominant flu strains months in advance, a challenge that contributes to variable vaccine effectiveness, which can range from about 60% in well-matched seasons to much lower levels when the match is poor.

Moderna indicated that limited supplies of mFlusiva might become available through select retailers for the 2026-2027 flu season, although most of the year's vaccine procurement was completed before the approval, which could delay broader distribution.

The agency’s decision also provides data that could support future combination vaccines targeting both influenza and COVID-19, though any such product would require separate regulatory review.