FDA Approves First mRNA-Based Flu Vaccine for Seniors

The US Food and Drug Administration has officially approved the first mRNA-based flu vaccine for adults aged 50 and older, as announced by drugmaker Moderna. “Flu remains a significant public health challenge, and mFLUSIVA provides an important new option for America’s seniors,” stated Moderna CEO Stephane Bancel. He added, “This approval also reflects the ongoing potential of our mRNA platform to help address important public health challenges through continued scientific innovation.”

In clinical trials, the new vaccine demonstrated approximately 27% greater effectiveness during the 2024–25 respiratory virus season compared to standard flu shots, with over 40,000 adults aged 50 and older participating in the study. Some side effects reported included injection-site reactions like pain and tenderness, fatigue, headaches, muscle or joint pain, nausea, vomiting, and fever.

For traditional flu vaccines, experts choose the strains for the upcoming fall season in February. However, Moderna’s mRNA flu vaccine allows for a shorter time frame between strain selection and public availability, potentially improving the match between vaccine-induced immunity and the circulating influenza strains. Moderna anticipates that the vaccine will be available this fall.

Earlier this year, the FDA initially rejected Moderna’s review request for the flu vaccine due to concerns over trial adequacy. However, the agency reversed its decision about two weeks later, agreeing to review the vaccine. Moderna's mRNA technology has also been applied in its Covid-19 vaccines, and Pfizer is also developing mRNA-based flu vaccines. A combined Covid-19 and flu mRNA vaccine from Moderna received approval in Europe this year.

Despite the rapid development of mRNA Covid-19 vaccines being a significant achievement during President Donald Trump’s first term, his administration has since retracted support for mRNA technology in infectious diseases. In August 2025, the US Department of Health and Human Services canceled 22 projects worth about $500 million related to mRNA vaccine development, with HHS Secretary Robert F. Kennedy Jr. controversially asserting, “these vaccines fail to protect effectively against upper respiratory infections like COVID and flu.”

Nonetheless, in June, an independent vaccine advisory panel from the FDA unanimously concluded that the advantages of Moderna's new vaccine outweigh the risks. They supported traditional approval for individuals aged 50 to 64 and accelerated approval for those aged 65 and older, which will necessitate further trials to validate clinical benefits.

Typically, the US Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices reviews new vaccines and provides recommendations. However, a federal judge ruled in March that Kennedy improperly replaced all committee members, resulting in no meetings since. The next meeting for the committee is scheduled for October.