FDA approves Moderna's mRNA flu vaccine mFlusiva for adults 50+, experts warn of public hesitancy
The FDA has authorized Moderna's mFlusiva, an mRNA-based influenza shot, for people aged 50 and older, citing a 26.6% higher efficacy than standard flu vaccines, while health officials note that misinformation may limit uptake.
The U.S. Food and Drug Administration granted approval on Wednesday for Moderna's mFlusiva, an mRNA influenza vaccine, for adults 50 years and older. A trial involving more than 40,000 participants aged 50 to 64 showed the product was 26.6% more effective than a conventional full-dose flu shot in preventing symptomatic illness. Approval for those 65 and older is provisional pending additional studies, and Moderna is also testing the vaccine in younger adults and adolescents.
Dr. Martín Bäcker, a principal investigator at the NYU Langone-Long Island Vaccine Center, said the approval demonstrates that mRNA technology can be applied to common diseases and that the study confirmed the vaccine’s performance compared with traditional formulations. Dr. Sharon Nachman, chief of pediatric infectious diseases at Stony Brook Medicine, noted that mFlusiva’s ability to be matched more closely to circulating flu strains each season could represent a "game changer" for vaccine effectiveness.
Unlike most flu vaccines, which are produced in chicken eggs, mRNA vaccines use the genetic sequence of the target virus to prompt an immune response. "It’s called a messenger for a reason," said Jeff Coller, a professor of RNA biology at Johns Hopkins University. Dr. Bruce Farber, chief of public health and epidemiology at Northwell Health, said the new shot could be dramatically more effective in years when traditional vaccines poorly match dominant strains, but emphasized that public acceptance will be a major challenge.
Vaccine confidence remains low; a recent KFF survey found that only 56% of Americans consider COVID-19 vaccines safe, and about a quarter of respondents believe mRNA vaccines can alter DNA. Flu vaccination rates in New York have slipped to roughly 48% for the 2024-25 season.
The FDA initially declined to review Moderna’s application for mFlusiva after criticism from some scientists and industry groups, but later reversed the decision. HHS Secretary Robert F. Kennedy Jr., a known vaccine skeptic, has questioned the efficacy of mRNA products, prompting a response from Coller that the secretary’s statements contradict the evidence. HHS spokeswoman Emily Hilliard said the department will continue to monitor safety and effectiveness data as it becomes available.