FDA Approves Moderna’s mRNA Flu Vaccine for Adults Ages 50 and Older
The U.S. Food and Drug Administration (FDA) has approved Moderna’s new seasonal influenza vaccine, the first flu shot in the United States to use messenger RNA (mRNA) technology.
Moderna announced Wednesday (Aug. 5) that an FDA advisory committee unanimously determined that the vaccine is safe and effective for preventing seasonal flu. Known as mFlusiva, or mRNA-1010, the vaccine is approved for adults ages 50 and older.
Like mRNA vaccines used against COVID-19, mFlusiva delivers genetic instructions that tell cells how to produce hemagglutinin, or HA. HA is a protein found on the surface of influenza viruses and is the primary target of traditional flu vaccines. After vaccination, the immune system learns to identify HA from the influenza strains included in the shot, helping it respond more effectively when exposed to those viruses.
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The HA protein changes quickly as influenza viruses evolve, making it difficult for conventional flu vaccines to perfectly match the strains circulating each season. Traditional vaccines also require months to manufacture. Because mRNA vaccines can be developed and produced more rapidly, the technology could make it easier to update flu shots to target the strains expected to dominate in a particular season.
The FDA’s decision was partly based on a late-stage clinical trial involving more than 40,000 adults ages 50 and older. Participants were vaccinated ahead of the 2024–2025 Northern Hemisphere flu season. About half received mFlusiva, while the remainder received a standard-dose conventional flu vaccine rather than the higher-dose flu shot approved for some older adults in the U.S.
Among the approximately 40,000 participants, about 970 developed influenza. The illness affected roughly 2% of people who received the mRNA vaccine, compared with 2.8% of those given the standard vaccine. Based on these results, mFlusiva was 26.6% more effective at preventing flu illness during the trial.
mFlusiva also provided greater protection against all three influenza subtypes included in the vaccine. Among adults ages 65 and older, the mRNA flu vaccine was 27.4% more protective overall than the standard-dose shot.
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Participants who received mFlusiva reported side effects such as pain at the injection site, headache, fatigue and muscle aches more often than those who received the conventional vaccine. However, the reactions were generally mild to moderate and short-lived, consistent with findings from earlier mRNA-1010 trials.
A separate trial involving adults ages 65 and older compared mFlusiva with a high-dose flu vaccine currently approved for older adults in the U.S. The results indicated that the mRNA vaccine produced a stronger immune response, based on antibody levels.
The findings led the FDA advisory committee to conclude that mFlusiva’s benefits outweigh its potential risks. The vaccine received standard approval for adults ages 50 to 64 and accelerated approval for people ages 65 and older. Additional studies will be conducted to confirm whether mFlusiva offers a meaningful advantage over high-dose flu vaccines in the oldest age group.
“Flu remains a significant public health challenge, and mFLUSIVA provides an important new option for America’s seniors,” Moderna CEO Stéphane Bancel said in a statement.
The approval comes as U.S. policy toward mRNA vaccine research and development continues to change.
During the second Trump administration, the federal government has reduced support for mRNA vaccine programs, including the cancellation of hundreds of millions of dollars in funding for research and development. Experts have said the moves could discourage investment in the field. Moderna has also scaled back some investments, citing opposition in the U.S. market. Health Secretary Robert F. Kennedy Jr. has also repeatedly expressed opposition to mRNA technology.
When Moderna first submitted mFlusiva for FDA approval in February, the agency declined to review the application. The FDA reversed that decision one week later, although experts said the reason for the change was unclear.
This article is for informational purposes only and is not intended to provide medical advice.
Source: www.livescience.com