The U.S. Food and Drug Administration on Wednesday approved the country's first mRNA-based flu vaccine, clearing Moderna's mFLUSIVA for adults aged 50 and older.
"Flu remains a significant public health challenge, and mFLUSIVA provides an important new option for America's seniors," Moderna CEO Stephane Bancel said. The vaccine was about 27% more effective than standard flu shots during the 2024-25 respiratory virus season in a trial that enrolled more than 40,000 adults.
The approval covers traditional approval for adults 50 to 64 and accelerated approval — which requires further trials to confirm clinical benefit — for those 65 and older. Side effects were typical for vaccines: injection-site pain, fatigue, headache and fever. Moderna says the shot should be available this fall.
The technology's real promise is speed. For conventional flu vaccines, experts pick the strains in February, months before the season. An mRNA vaccine needs less time between strain selection and circulation, allowing a closer match between the vaccine and the flu strains actually circulating.
The path to approval was rocky. The FDA initially declined to review the vaccine in February, citing inadequate trials, before reversing course about two weeks later. In June, the agency's independent vaccine panel voted unanimously that the benefits outweigh the risks.
The approval arrives amid political friction over mRNA science: Health and Human Services Secretary Robert F. Kennedy Jr.'s department canceled about $500 million in mRNA vaccine development projects last August, claiming "these vaccines fail to protect effectively" — against the evidence. The CDC's vaccine advisory committee, whose members Kennedy replaced in a process a federal judge ruled unlawful, has not met since March and is next scheduled to convene in October.
