FDA Approves First Mrna Flu Vaccine for Adults Aged 50 and Over

The US Food and Drug Administration has approved Moderna’s mFLUSIVA, the first mRNA-based vaccine against seasonal influenza, for adults aged 50 years and older. The vaccine is expected to become available in the United States for the 2026–2027 respiratory virus season and offers a new option alongside existing flu vaccines.

First mRNA vaccine against seasonal flu

mFLUSIVA, also known as mRNA-1010, uses technology similar to that used in mRNA COVID-19 vaccines.

The FDA approved the vaccine for adults aged 50 and over. For adults aged 50 to 64, approval was based on a large phase 3 clinical trial. For adults aged 65 and over, the vaccine received accelerated approval.

Phase 3 trial included more than 40,000 adults

The main phase 3 trial involved more than 40,000 adults aged 50 years and older across 11 countries.

Around half received mFLUSIVA, while the other half received a licensed standard-dose influenza vaccine.

Researchers concluded that mFLUSIVA was superior to the standard-dose vaccine in preventing laboratory-confirmed flu-like illness.

For adults aged 50 to 64, the trial showed approximately 27% greater relative vaccine efficacy compared with the standard-dose flu vaccine.

Separate data for adults aged 65 and over

Accelerated approval for adults aged 65 years and older followed a clinical trial involving more than 2,900 adults in the United States.

That study compared the immune response generated by mFLUSIVA with that of a high-dose inactivated flu vaccine.

Experts noted that this distinction is important because additional post-approval evidence is still required to confirm clinical effectiveness in the older age group.

Faster production could help match changing flu strains

One potential advantage of mRNA technology is speed.

Traditional egg-based influenza vaccines can take at least six months to manufacture. Because influenza viruses are constantly changing, the circulating strains may shift during that production period.

mRNA vaccines can be produced more quickly and may therefore offer greater flexibility when influenza strains change.

A new option, not a replacement for every flu vaccine

Experts quoted in the article cautioned that mFLUSIVA should not be viewed as a replacement for all existing influenza vaccines.

Instead, it represents an additional option for physicians and patients, particularly for people at higher risk of complications from influenza.

For the 2026–2027 season, the key message remains to receive an appropriate flu vaccine rather than wait for a “perfect” option.

Possible side effects

Side effects reported in clinical trials included:

headache
fatigue
joint pain
muscle pain
nausea
vomiting
fever
chills

Injection-site reactions were also reported. In rare cases, severe allergic reactions or anaphylaxis may occur.

Precautions before vaccination

Moderna recommends informing a healthcare professional before vaccination if a person has previously had an allergic reaction to a vaccine, is immunocompromised, takes medication affecting the immune system, has had Guillain-Barré syndrome after a flu vaccine, or is pregnant, breastfeeding or planning pregnancy.

The company advises against receiving mFLUSIVA in people who have had a severe reaction to any of its ingredients.