The US Food and Drug Administration approved Moderna's mRNA-based influenza vaccine, mFLUSIVA, on August 5 for adults aged 50 to 64, while granting accelerated approval for individuals aged 65 and older. Nature reported that the company plans to make the shot available in the United States within weeks for the 2026–27 influenza season.
Clinical trials involving more than 40,000 adults demonstrated that 2% of participants who received mFLUSIVA developed laboratory-confirmed influenza, compared with 2.8% of those who received a standard-dose non-mRNA comparator vaccine. That outcome reflected a 26.6% relative reduction in confirmed flu cases against three World Health Organization-recommended strains selected for the 2024–25 Northern Hemisphere season.
Moderna, based in Cambridge, Massachusetts, designed the vaccine—previously designated mRNA-1010—to deliver mRNA molecules encoding the influenza virus's hemagglutinin surface protein inside lipid nanoparticles. Once inside host cells, the mRNA translates into the hemagglutinin protein, triggering antibody production. Emanuele Montomoli, a public health researcher at the University of Siena, told Nature that the mRNA platform enables rapid reformulation to match circulating strains and helps address manufacturing delays.
Trial participants tolerated the shot well overall, with mild to moderate adverse effects such as fatigue, headache, and injection-site pain reported most frequently. Injection-site pain occurred more than twice as often in mFLUSIVA recipients compared to those receiving standard vaccines. For individuals aged 65 and older, a separate study found that a single dose generated stronger antibody responses than both standard-dose and high-dose licensed shots.
Regulators in Australia, Canada, and the European Union are currently reviewing mFLUSIVA. In April, the European Commission authorized Moderna's combined influenza and COVID-19 mRNA vaccine, mCombriax. Under the terms of the US accelerated approval, Moderna agreed to conduct a phase IV confirmatory trial evaluating mFLUSIVA's efficacy relative to enhanced vaccines in adults aged 65 and older.
