Federal vaccine advisers have recommended Moderna’s MFLUSIVA review, moving the first mRNA influenza vaccine closer to possible U.S. approval for adults 50 and older before the coming winter flu season.
The vote came from the FDA’s independent vaccine advisory panel, which reviewed safety and effectiveness data for MFLUSIVA, an influenza vaccine made by Moderna. The committee voted unanimously that the vaccine’s benefits appear to outweigh its risks for adults ages 50 to 64 and for adults 65 and older.
The decision now goes to the Food and Drug Administration, which will consider the recommendation before issuing a final decision. Moderna is seeking full approval for people ages 50 to 64. The company is also seeking authorization for those 65 and older while it conducts additional testing.
A New Flu Shot Moves Toward Approval
Seasonal influenza remains a serious threat for older adults, who face higher risks of hospitalization and death when flu spreads widely. Tens of thousands of people in the United States die from influenza in many years and seniors often carry the heaviest burden.
The FDA panel’s recommendation marks a major step for mRNA technology beyond COVID-19 vaccines. If the agency approves MFLUSIVA, it would add a new manufacturing approach to the seasonal flu vaccine lineup in the United States.
Current flu vaccines use several platforms. Some are egg-based, some are cell-based and some use recombinant protein technology. Each year, vaccine makers prepare doses months ahead of flu season using strains chosen through global surveillance.
MFLUSIVA uses messenger RNA, the molecule that gives cells instructions for making a target protein. In a vaccine, that instruction is designed to train the immune system to recognize influenza proteins before a person encounters the virus.
The panel vote does not immediately place the shot in pharmacies or doctors’ offices. It gives the FDA expert advice as the agency weighs approval, labeling, post-market requirements and any remaining data needs before winter.
What the FDA Panel Reviewed
The Vaccines and Related Biological Products Advisory Committee met to discuss the safety and effectiveness of MFLUSIVA, manufactured by Moderna TX Inc. The requested indication covers prevention of influenza disease caused by influenza A subtypes and type B viruses represented in the vaccine.
Panel members considered data from a large study involving about 40,000 people ages 50 and older. That trial compared Moderna’s mRNA shot with a routinely used flu vaccine brand. The review also included a smaller study in people 65 and older.
For adults ages 50 to 64, Moderna is seeking full approval. For adults 65 and older, the company is seeking authorization while a larger follow-up study continues. That distinction matters because seniors can respond differently to vaccines than younger adults.
The FDA also reviewed the vaccine’s side-effect profile. According to the reported data, there were no major safety issues. Temporary reactions occurred, including injection-site pain, fever, headache, tiredness and body aches.
Those reactions are familiar across many vaccines. They also appeared somewhat more often than with some existing flu shots. FDA reviewers said that pattern is typical for mRNA vaccines.
How mFlusiva Performed in Older Adults
In the 40,000-person study, Moderna’s mRNA vaccine reduced flu cases by about 27 percent compared with another routinely used flu vaccine brand. That result gave advisers direct evidence from a large older-adult population.
The smaller study in people 65 and older examined immune responses against flu strains. Moderna’s shot generated a strong immune response compared with a high-dose flu vaccine already recommended for that age group.
During the advisory discussion, Dr. Anna Durbin of Johns Hopkins University said the immune-response data “were very compelling.” She also said, “The vaccine looks very promising.”
Those comments reflect a key question in flu vaccine review. Regulators want to know whether a vaccine prevents illness in real people. They also examine whether the immune system responds strongly enough to suggest protection in groups where direct case-count data may be limited.
For seniors, that second question is especially important. Immune systems often become less responsive with age. That is one reason the United States already recommends certain enhanced flu vaccines for people 65 and older.
Why mRNA Could Matter for Flu Season
Flu viruses change constantly. Each year’s vaccine formula is based on predictions about which strains are likely to circulate months later. When circulating strains drift away from the vaccine recipe, protection can weaken.
mRNA vaccines can be made faster than many older vaccine platforms. That speed could help manufacturers respond if influenza changes after strain decisions are made. It could also help public health agencies prepare for unusual or rapidly emerging flu strains.
Dr. Flor Munoz-Rivas of Texas Children’s Hospital, one of the FDA advisers, highlighted that potential during the meeting. “Having this technology available puts us in a better position to be prepared for emerging strains in the future,” she said.
The logic is straightforward. Instead of growing large amounts of virus in eggs, mRNA manufacturing builds genetic instructions for the chosen influenza targets. Once scientists select the target sequence, manufacturers can adjust the vaccine design more quickly.
That flexibility could be useful for seasonal flu vaccines. It could also matter during a future outbreak when timing is critical. Still, approval for MFLUSIVA would focus on the specific use the FDA is reviewing, prevention of influenza in adults 50 and older.
Safety Findings From Moderna’s Studies
Safety is central to every vaccine review, especially for a shot intended for millions of older adults. Moderna’s data showed no major safety concerns in the studies described to advisers.
The most common reactions were temporary. They included injection-site pain, fever, headache, tiredness and aches. These symptoms generally reflect the immune system responding after vaccination.
Panelists also discussed the need for more information in certain groups. Frail seniors and people with weakened immune systems can have different risks and different immune responses. FDA reviewer Dr. Timothy Brennan suggested the agency was open to approval for older adults ahead of the coming season while acknowledging the need for more data.
That kind of staged evidence gathering is common in vaccine regulation. A vaccine can be supported by large trials and still require continued monitoring after wider use. Real-world data can reveal how well a shot performs across varied health conditions, medications and age ranges.
Moderna’s next-step study is expected to include 400,000 people ages 65 and older. Half would receive the mRNA vaccine. The other half would receive one of the existing flu shots designed for seniors. The company is expected to repeat that study across two flu seasons.
What Happens Before Winter
The FDA will now decide whether to follow the advisory committee’s recommendation. The agency often considers panel votes closely, although the final regulatory decision belongs to FDA officials.
A decision is expected by early August. That timing matters because flu vaccination campaigns usually begin before influenza activity rises in the fall and winter. Health systems, pharmacies and manufacturers need time to prepare supply and guidance.
If approved, MFLUSIVA would enter a flu vaccine landscape that already includes several options. For people 65 and older, U.S. recommendations currently favor certain higher-dose or enhanced vaccines because they can produce stronger protection in seniors.
The broader scientific significance comes from the platform. mRNA became widely known during the COVID-19 pandemic, when it allowed vaccine developers to move quickly after the coronavirus genome was published. Influenza presents a different challenge because its strains shift year after year.
For now, the FDA review places MFLUSIVA at a late regulatory checkpoint. The advisory vote signals confidence in the benefit-risk profile presented to the committee. The next milestone is the agency’s final decision, which will determine whether this first mRNA flu vaccine can be used in older Americans during the 2026-2027 flu season.
