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The Food and Drug Administration has approved Moderna’s mFlusiva, the first U.S. influenza vaccine made with messenger RNA technology. The new mRNA flu vaccine is intended for adults age 50 and older.
Moderna expects limited supplies to reach select retailers ahead of the 2026-2027 flu season. Other seasonal flu vaccines have already started arriving at pharmacies and medical offices.
Approval Covers Adults Age 50 and Older
The FDA granted traditional approval for mFlusiva in adults ages 50 through 64. That decision was based on a large clinical trial involving about 40,000 adults.
The study found approximately 27% fewer flu cases among mFlusiva recipients compared with people receiving a standard flu vaccine.
For adults age 65 and older, the FDA granted accelerated approval. That pathway allows a product to reach patients based on evidence considered likely to predict a clinical benefit.
A smaller study found that mFlusiva produced a strong immune response when compared with an existing high-dose flu vaccine for older adults. Moderna must conduct an additional study to confirm its benefits in that age group.
How the mRNA Flu Vaccine Works
Traditional flu vaccines often use weakened, inactive or laboratory-produced pieces of influenza viruses. Many are manufactured using chicken eggs, a process that can take several months.
MFlusiva instead delivers genetic instructions that teach cells to produce harmless proteins resembling parts of the influenza virus. The immune system then learns to recognize those proteins and respond to future exposure.
The vaccine does not contain a live influenza virus. Its mRNA also does not enter the cell’s nucleus or change a person’s DNA.
MFlusiva targets three influenza strains: A/H1N1, A/H3N2 and the B/Victoria lineage. The FDA’s scientific review describes it as a single intramuscular injection supplied in a prefilled syringe.
Study Found No Major Safety Problems
Moderna’s clinical data identified no major safety concerns. However, short-term reactions occurred somewhat more frequently with mFlusiva than with traditional flu shots.
Reported reactions included pain at the injection site, fever, headache, fatigue and muscle aches. Those effects were generally temporary.
An independent FDA advisory committee reviewed the evidence in June. The panel unanimously concluded that the vaccine’s benefits outweighed its risks for both approved age groups.
The FDA initially declined to review Moderna’s application earlier in 2026, citing concerns about the submission and study design. The agency reversed that decision after the company amended its application.
New Option Arrives Before Flu Season
Seasonal influenza vaccines require regular updates because circulating viruses change over time. Manufacturers select new formulations each year based on strains expected to spread during the upcoming season.
Messenger RNA vaccines can be redesigned and manufactured more quickly than many traditional shots. That speed could become important if influenza strains change unexpectedly or a new pandemic threat emerges.
MFlusiva will join several existing flu vaccines for older adults. Current federal guidance recommends enhanced vaccines for people age 65 and older when they are available.
The new approval does not change the general recommendation that most people age 6 months and older receive an annual flu vaccine. Vaccine selection should account for a person’s age, health conditions and medical history.
Availability and insurance coverage may differ by pharmacy or health provider. Adults interested in mFlusiva can confirm local supply and eligibility as the fall vaccination season approaches.