WASHINGTON — The U.S. Food and Drug Administration has approved Moderna's mRNA-based seasonal influenza vaccine, marking the first authorization of an influenza vaccine using messenger RNA technology and expanding the platform beyond COVID-19 vaccines.
The vaccine, to be marketed as mFlusiva, is approved for adults aged 50 years and older. The FDA granted traditional approval for people aged 50 to 64 and accelerated approval for adults aged 65 and older, with the latter contingent on additional post-marketing studies to confirm clinical benefit in the older population, according to the agency's decision and the company.
The approval follows months of regulatory scrutiny after the FDA initially declined to review Moderna's application in February, citing concerns over the design of the company's late-stage clinical trial. The agency later reversed that decision after Moderna agreed to conduct additional research in older adults, allowing the application to proceed.
In June, the FDA's Vaccines and Related Biological Products Advisory Committee voted unanimously that the vaccine's benefits outweighed its risks for adults aged 50 and older, clearing the way for the agency's final review.
The approval was supported by a Phase 3 study involving more than 40,000 participants. According to Moderna and FDA briefing documents, the vaccine demonstrated approximately 26.6% greater effectiveness than a licensed standard-dose influenza vaccine in preventing laboratory-confirmed influenza and generated stronger immune responses than Sanofi's high-dose influenza vaccine in older adults. Common side effects included injection-site pain, fatigue and headache, with no major new safety concerns identified during the trial.
Messenger RNA vaccines instruct cells to produce proteins that trigger an immune response rather than relying on viruses grown in eggs or cell cultures. Supporters of the technology say it could allow manufacturers to update influenza vaccines more rapidly when circulating strains change.
The decision represents an important milestone for Moderna as it seeks to diversify its business following declining demand for COVID-19 vaccines. The company has also been developing combination vaccines targeting both COVID-19 and seasonal influenza, although regulatory review of that program has faced delays.
Commercial uptake of mFlusiva may take time because many vaccine purchasing agreements for the upcoming influenza season have already been established. Analysts have said more meaningful sales are likely beginning with subsequent flu seasons, while additional studies required under the accelerated approval pathway will determine whether the vaccine's indication for older adults can be fully confirmed.
