FDA approves Moderna's mRNA flu vaccine for adults 50-64, grants accelerated approval for seniors

The U.S. Food and Drug Administration approved Moderna's mRNA flu vaccine, mFLUSIVA, for adults aged 50-64 on 5 August and granted accelerated approval for people 65 and older. Moderna expects the product to be available within weeks for the 2026-27 flu season in the United States.

The vaccine uses messenger RNA to encode the influenza hemagglutinin protein, which is delivered in lipid nanoparticles. In clinical trials involving more than 40,000 participants, 2 % of recipients of mFLUSIVA developed laboratory-confirmed influenza compared with 2.8 % of those who received a standard non-mRNA vaccine, representing a 26.6 % relative reduction in cases.

"The key questions regarding immunogenicity, efficacy and safety have been addressed, which enabled the licensure of mFLUSIVA," said Raffael Nachbagauer, vice-president of infectious-disease research at Moderna.

Researchers highlighted the platform’s ability to be reformulated quickly to match circulating strains. Emanuele Montomoli, a hygiene and public-health researcher at the University of Siena, called the approval a potential "game changer" for addressing slow manufacturing timelines.

The vaccine was generally well tolerated; the most common adverse events were mild to moderate injection-site pain, fatigue and headache, occurring more frequently than with standard-dose comparators. A separate study in adults 65 and older showed that a single dose of mFLUSIVA generated stronger antibody responses than existing standard-dose and high-dose flu shots.

"A relative improvement over a standard-dose influenza vaccine is already clinically meaningful," said Federico Martinón-Torres, head of paediatrics at the University Clinical Hospital of Santiago de Compostela.

Regulatory reviews are ongoing in the European Union, Canada and Australia. Earlier in April, the European Commission approved Moderna's combined seasonal influenza and COVID-19 mRNA vaccine, mCombriax.