FDA Approves Moderna's mRNA Flu Vaccine Amid Political Backlash

The FDA has approved Moderna's mRNA flu shot, the first of its kind, for adults 50 and older, despite political controversy and an initial refusal.

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The U.S. Food and Drug Administration has given the green light to Moderna's mRNA-based seasonal flu vaccine, mFlusiva (also known as mRNA-1010), making it the first mRNA flu shot to receive regulatory approval. The vaccine is authorized for adults aged 50 and above, with a standard approval for those 50 to 64 and an accelerated approval for individuals 65 and older. It targets the four most common influenza strains and has been under human testing since 2021.

The approval is backed by a Phase 3 trial that enrolled over 40,000 adults across 11 countries, with one source citing nearly 44,000 participants. During the 2024-2025 Northern Hemisphere flu season, about 970 individuals contracted the flu: 2% of those who received the mRNA vaccine versus 2.8% of those given a standard-dose conventional vaccine, indicating a 26.6% overall reduction in flu risk. Among those aged 65 and older, the mRNA vaccine was 27.4% more protective. The shot also proved superior against each of the three flu subtypes covered by the vaccine.

Moderna reported that the vaccine outperformed standard-dose licensed vaccines in preventing influenza-like illness in adults over 50. An additional trial comparing mFlusiva with a high-dose flu vaccine in seniors showed that the mRNA shot elicited stronger immune responses based on antibody levels. As part of the accelerated approval for those 65 and older, further studies are required to confirm its benefit over the high-dose alternative.

Solicited adverse events were more frequent with mRNA-1010, including injection-site pain, fatigue, headache, and myalgia, but most were mild to moderate and transient.

The approval comes amid a politically charged atmosphere. The FDA initially declined to review Moderna's application in February, citing that the comparator vaccine did not represent the best available standard of care and preferring a higher-dose vaccine for older adults. This was despite the FDA having previously told Moderna that a licensed standard-dose vaccine as a comparator was acceptable. The agency reversed its decision within a week, and an advisory committee unanimously voted in favor of approval in June.

Critics have labeled the initial refusal as politically motivated. Law professor Richard Hughes IV commented, "It's all pretext and obfuscation when the real agenda is rejecting conventional science and serving a predetermined anti-vaccine agenda." The reversal followed reports that the director of drug approval had overruled career scientists.

Meanwhile, the second Trump administration has been withdrawing federal support for mRNA vaccines, canceling hundreds of millions in research and development funds. Health Secretary Robert F. Kennedy Jr., who has repeatedly voiced opposition to mRNA technology, canceled a federal campaign to encourage flu shots earlier this year, even during a severe flu season and despite the CDC having already paid for it.

Moderna CEO Stéphane Bancel said: "Flu remains a significant public health challenge, and mFLUSIVA provides an important new option for America's seniors."