The U.S. Food and Drug Administration has approved Moderna’s mRNA-based flu vaccine, named mFlusiva, offering a new tool for adults aged 50 and over ahead of the upcoming respiratory virus season, according to reports from the Associated Press and NPR. Clinical trials showed the new messenger RNA shot was 27% more effective than the standard flu shot, according to coverage by HuffPost.
Regulatory Approval Status and Age Brackets
The FDA granted full approval for mFlusiva for adults aged 50 to 64, according to HuffPost. For adults aged 65 and older, the vaccine received temporary accelerated approval, as reported by HuffPost. Moderna is currently conducting an additional trial comparing the new vaccine to the current high-dose flu shot given to adults over 65, according to HuffPost. The vaccine is expected to be available in time for the upcoming respiratory virus season, though insurance coverage details remain uncertain, according to HuffPost.
How mRNA Technology Applies to Influenza
The vaccine utilizes messenger RNA technology, mirroring the platform used in COVID-19 vaccines, according to Dr. S. Dr. Onyema Ogbuagu, a professor of medicine and pharmacology at Yale School of Medicine, explained to HuffPost that influenza viruses continuously alter their genomes to evade natural or vaccine-induced immunity. This constant mutation causes significant mismatches during certain flu years, which correlates with higher rates of illness, hospitalizations, and deaths, such as during the flu season recorded nationwide last year, which was the worst in 25 years, according to HuffPost.

Manufacturing Agility and Potential Strain Updates
The mRNA platform allows for vaccines to be produced faster, according to Dr. Onyema Ogbuagu, as reported by HuffPost. Dr. Cynthia Leifer, a professor in the department of microbiology and immunology at Cornell University, explained to HuffPost that adjusting an mRNA vaccine to match a newly circulating variant does not require changing the entire vaccine. Because the platform delivers blueprints, manufacturers can modify small parts rapidly once dominant strains are identified, according to HuffPost.
Clinical Trial Safety and Side Effect Profiles
Moderna tested mFlusiva in a trial of about 40,000 people, according to HuffPost. Because the mRNA vaccines generate a stronger immune response than traditional flu vaccines, clinical trial participants experienced stronger side effects, according to Dr. S. Expected mild reactions include fatigue, injection site pain, headaches, and low-grade fevers, according to HuffPost.
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