FDA Panel Backs mFlusiva mRNA Flu Shot for Elderly

Despite a number of significant limitations in the available safety and efficacy data for licensure review of Moderna, Inc.’s new mRNA influenza biologic mFlusiva, the U.S. Food and Drug Administration’s (FDA) Vaccines and Related Biological Products Advisory Committee ((VRBPAC) voted on June 18, 2026 to recommend fast-tracked licensure of the first mRNA product to target seasonal influenza for use in adults 65 and older and for a traditional approval process for adults 50 to 64 years of age.^{1 2}

During discussions on the safety and efficacy data submitted by Moderna for accelerated approval of its experimental mRNA (messenger ribonucleic acid) annual flu shot for seniors over age 65, including those who are frail, the FDA advisory panel determined that the benefits of administering mFlusiva (formerly mRNA-1010) outweighs its risks and voted unanimously (9 to 0) to recommend favorable consideration by the FDA.^{1 2}

Speed and Efficacy Rule the Day

Perhaps the biggest argument made during the VRBPAC meeting for switching to mRNA based biologicals from traditional influenza vaccines that use eggs and insect cells for production is the greater production speed offered by the mRNA technology, which also allows a more timely prediction of circulating strains to more accurately match the vaccine strains. In other words, mRNA technology provides drug companies with an accelerated production process that cuts down on research and development costs and makes it easier to match circulating strains with strains included in the vaccine.

In Moderna’s presentation to the panel, Rituparna Das, MD, PhD noted that “current influenza vaccine technologies can be affected by the long interval between strain selection and vaccination.”² She added:

By directly encoding the selected antigen sequence, avoiding egg adaptation and supporting a more flexible manufacturing timeline, mRNA-1010 has the potential to address important limitations of current influenza vaccines and improve protection in a population that continues to experience substantial influenza disease burden.²

According to panel member Flor Muñoz-Rivas, MD of Texas Children’s Hospital:

Having this technology available puts us in a better position to be prepared for emerging strains in the future.¹ 

The members of the panel were presented with data showing a 26.6 percent higher efficacy of mFlusiva than a licensed standard-dose flu vaccine. This may well have been the deciding factor, “It’s great to see the higher efficacy compared to existing vaccines,” said panel member Adam Berger, PhD of the National Institutes of Health (NIH). However, the study demonstrating superior efficacy only evaluated one influenza season and different strains can circulate in different flu seasons, meaning critical long term efficacy data is missing.^{2 3}

And it probably would have been more revealing to compare mFlusiva’s efficacy with that of the high-dose, recombinant, or adjuvanted influenza vaccines recommended by the U.S. Centers for Disease Control and Prevention (CDC) for elderly individuals.⁴

Safety, Not So Much

Clearly, any safety concerns about mFlusiva were minimized in panel discussions. Dr. Berger, for example, said that evidence “largely supports the safety and effectiveness” of the biologic. He characterized the safety data as “relatively reassuring.” Not exactly a strong vote of confidence for this experimental biologic that employs a new and extremely controversial technology (mRNA) for which there are no good long-term safety studies.²

Berger’s lukewarm comments on the safety aspects of the product are particularly troubling, given no safety studies have been done on the health impacts of administering mFlusiva to patients, who have also received one or more other routinely recommended respiratory vaccines such as COVID-19, RSV (Respiratory Syncytial Virus), and pneumococcal vaccines, or will receive them simultaneously in the future. Also, studies were not done giving mFlusiva to immunocompromised individuals.  Very frail older adults with co-morbidities were not included in the clinical trials for the product, two groups which Nicholas Jacobus pointed out in a PharmExec.com article are “most likely to respond differently to mRNA-based vaccine platforms.”^{4 5}

These are no small gaps in data and fundamental understanding of the risk profile of mFlusivia. The lack of evidence for safety in the vulnerable elderly population appears to have been minimized and conveniently shoved aside by VRBPAC.

A decision by the FDA on mFlusiva is expected to be made by Aug. 5, 2026. If the licensure application for the experimental biologic is approved, it would make mFlusiva the the first mRNA-based seasonal flu shot in the United States.³

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