FDA Grants Approval to Moderna's mRNA Seasonal Flu Vaccine for Adults 50+

The U.S. Food and Drug Administration has approved Moderna's mRNA-based seasonal flu vaccine, mFlusiva (mRNA-1010), for adults 50 years and older, the company said in a press release. The vaccine targets the four strains of influenza most commonly circulating each season and has been studied in human trials since 2021.

In a Phase 3 trial that enrolled 40,805 participants across 11 countries, the vaccine demonstrated superior protection against influenza-like illness compared with a licensed standard-dose flu vaccine. The study also reported higher rates of solicited adverse events such as injection-site pain, fatigue, headache and muscle aches, which were described as mostly mild to moderate and transient.

The approval includes a standard authorization for adults aged 50-64 and an accelerated approval pathway for those 65 and older. > "mRNA-1010 was superior to standard-dose licensed vaccines for prevention of…influenza-like illness in adults 50 years of age or older," the study authors wrote.

The FDA initially declined to review Moderna's application, citing concerns that the comparator vaccine used in the trial did not represent the best available standard of care in the United States. After the agency later indicated that a licensed standard-dose influenza vaccine would be an acceptable comparator, it reversed its position and proceeded with the review.

Critics had previously characterized the FDA's initial refusal as politically motivated. Law professor Richard Hughes IV told The Guardian that the move was "pretext and obfuscation" aimed at an "anti-vaccine agenda." The agency’s subsequent decision to approve the vaccine reflects its assessment that the data meet regulatory standards.