FDA clears Moderna’s mRNA flu vaccine

The U.S. Food and Drug Administration has approved Moderna’s mRNA-based influenza vaccine, mFlusiva (mRNA-1010), for adults aged 50 and older. This decision makes mFlusiva the first mRNA-based seasonal flu vaccine authorized for use in the United States. The approval follows a formal regulatory review that covered safety, efficacy and manufacturing data for the product.

Regulators differentiated the approval pathway by age group. Adults between 50 and 64 years received traditional, or standard, approval, while adults aged 65 and older received accelerated approval. The accelerated pathway for the older population is contingent on Moderna providing additional clinical data to confirm clinical benefit in that age group.

The FDA’s decision was underpinned by a late-stage clinical trial that enrolled more than 40,000 adults aged 50 and above. In this study, mFlusiva demonstrated roughly 26.6% to 27% relative vaccine efficacy compared with a licensed standard-dose flu shot over the duration of follow-up. In practical terms, the mRNA vaccine was about 27% more effective than the comparator at preventing influenza illness under the conditions studied.

The trial focused on adults in the same age range covered by the approval, providing evidence across both the 50–64 and 65-plus populations. These data supported full approval in the younger cohort and contributed to the accelerated approval decision in older adults, where further confirmation will be provided by ongoing or future studies.

Adverse reactions were more frequent with mFlusiva than with the standard-dose comparator, but most events were described as mild to moderate and transient. Reported side effects included injection-site pain and tenderness, as well as swollen lymph nodes near the injection area.

Systemic reactions such as fatigue, headache, muscle or joint pain, nausea or vomiting, and fever were also observed. These side effects are consistent with heightened reactogenicity seen with mRNA platforms, but remained generally short-lived in the trial population.

Before granting approval, the FDA’s independent vaccine advisory committee voted unanimously in June to recommend that the agency authorize mFlusiva. Earlier in the year, the FDA had initially declined Moderna’s request for review of the application but subsequently reversed that decision and proceeded with full evaluation. The final approval represents a regulatory turnaround from that earlier stance.

Moderna has stated that it expects to have mFlusiva available for the 2026–2027 flu season, described as this fall’s flu season in the reporting. With authorization now in place, the company can move ahead with supplying doses for adults aged 50 and older, including those covered under the accelerated approval, as additional data collection continues.