The Food and Drug Administration has approved a first-of-its-kind flu vaccine made with messenger RNA technology, enabling its developer, Moderna, to complete a dramatic regulatory turnaround.
The agency on Wednesday approved mFlusiva, previously known as mRNA-1010, for use against seasonal influenza in all adults at least 50 years of age. The shot’s clearance in those 65 or older was handed out under an “accelerated” approval that’s contingent on results from a postmarketing study. Moderna previously disclosed that it’s already aligned with regulators on the framework of that trial, which will take place over the course of two flu seasons.
"Flu remains a significant public health challenge, and mFlusiva provides an important new option for America's seniors,” said Moderna CEO Stéphane Bancel, in a statement. “This approval also reflects the ongoing potential of our mRNA platform to help address important public health challenges through continued scientific innovation.”
Like the rest of Moderna’s pipeline, mFlusiva is built on mRNA technology capable of being weaponized against emerging pathogens more quickly than traditional vaccines. That speed advantage helped Moderna bring one of the first COVID-19 vaccines to market during the pandemic, and made Moderna a household name.
Sales of that COVID-19 vaccine have fallen considerably since then, and even with other product approvals, Moderna has struggled to find another big seller. It’s long hoped mFlusiva could be a big part of the solution, given current flu shots are based on a slower production process that relies more heavily on expert guesswork to determine which viral strains to target.
That vaccine, though, has faced an unusual and tumultuous regulatory path. Moderna first sought clearance of a combination COVID and flu shot, but abandoned that plan after U.S. regulators requested additional data from its influenza component. Moderna gathered those results, which were published in the New England Journal of Medicine and showed that, when compared to a standard-dose flu vaccine, mFlusiva reduced the likelihood of influenza-like illness by 27% in adults 50 years of age or older. Yet the FDA — led at the time by Marty Makary and top deputy Vinay Prasad — refused to review the application.
The unusual decision drew public backlash, though, and the agency quickly reversed course after a formal meeting with Moderna. And Prasad and Makary, who had enacted stricter vaccine approval guidelines, have both since left the FDA. Interim leaders have appeared to take a friendlier stance on multiple other delayed or previously spurned drug applications, heightening Moderna’s chances at a comeback.
In June, an FDA advisory committee then threw unanimous support behind mFlusiva. The panelists determined that the benefits of vaccination with Moderna’s shot outweigh the risks in adults between 50 and 64 years of age. They were also supportive of use in those 65 and older, despite agency reviewers’ concerns with certain gaps in the evidence Moderna had accumulated. The confirmatory study is meant to address those issues.
No new or serious safety concerns were identified by either Moderna or FDA staff reviewers. Adverse reactions consistent with mRNA vaccines, such as fatigue, joint pain and muscle aches, were recorded in the trial.
“The studies that were presented today were very well conducted. They have very clear results that are very robust,” said Flor Munoz-Rivas, a panelist and associate professor of pediatrics and infectious disease at Baylor College of Medicine, at the meeting. An approval would help the U.S. be “better prepared for emerging strains or pandemic strains in the future.”
Moderna expects mFlusiva to be available in the U.S. for the upcoming 2026-2027 flu season. The shot is under review in Europe, Canada and Australia, and other submissions are planned this year.
