Adults aged 50 and older have a new option for fall immunization after the U.S. Produced by Moderna, the shot uses lipid particles to deliver mRNA sequences into human cells, instructing them to temporarily produce a harmless hemagglutinin protein to stimulate an immune response against circulating influenza strains.
How the mRNA Flu Vaccine Works Compared to Traditional Shots
Traditional influenza vaccines often rely on inactivated viruses, purified viral proteins, or egg-based and cell-based manufacturing methods to provoke immunity. By contrast, mFLUSIVA delivers three mRNA sequences wrapped in fat-like molecules, teaching the immune system to recognize surface proteins without introducing a whole virus.
Clinical Trial Effectiveness and Side Effects
In a phase three clinical trial involving more than 40,000 adults aged 50 and older, 2% of participants who received mFLUSIVA developed flu illness compared to 2.8% of those who received a standard-dose inactivated vaccine, representing about a 27% lower relative risk. Short-term immune responses were common, with roughly 75% of mFLUSIVA recipients reporting mild to moderate reactions such as injection site tenderness, fatigue, and muscle aches, compared to 47% of the standard-dose group. Dr. Georges C. Benjamin, chief executive of the American Public Health Association, told The New York Times that removing the egg-based manufacturing process will allow public health agencies to adjust rapidly to newly emerging strains.
Did you know?
Unlike conventional vaccine production that relies heavily on cultivating viruses in eggs, mRNA manufacturing allows developers to copy viral sequences in a lab much faster, opening the door for quicker seasonal updates.
CDC Recommendations and Availability for Older Adults
The Centers for Disease Control and Prevention recommends that most eligible individuals receive their annual flu shot in September or October, allowing roughly two weeks for the body to build full protection. For adults aged 50 to 64, the CDC does not express a preference among licensed, age-appropriate options, meaning mFLUSIVA sits alongside standard inactivated and recombinant vaccines. For adults 65 and older, the agency has historically recommended enhanced vaccines, and mFLUSIVA is now approved for this population.
Co-Administering Fall Respiratory Vaccines
Health providers generally advise older adults to review their broader immunization needs during their fall visit.
Frequently Asked Questions
Can the mFLUSIVA vaccine give you the influenza virus?
No. The vaccine contains no whole flu virus, uses synthetic mRNA instructions that break down naturally, and cannot cause influenza.
Who is eligible to receive the new mRNA flu shot?
The FDA approved mFLUSIVA for adults aged 50 and older.
Can I get my flu shot and my COVID-19 booster at the same time?
Yes.
What are your plans for fall vaccinations this year? Share your thoughts or questions in the comments below.