FDA Approves Moderna mRNA Flu Vaccine mFlusiva for Adults 50 and Older
The FDA approved mFlusiva, the first mRNA-based seasonal flu vaccine, for adults aged 50 and older. Clinical trials showed the vaccine was about 26 to 27 percent more effective than standard flu shots, though distribution challenges remain due to a blocked CDC advisory committee.
The U.S. Food and Drug Administration approved mFlusiva, the nation's first mRNA-based seasonal influenza vaccine, for adults aged 50 and older in August 2026.
The FDA granted standard approval for adults aged 50 to 64 and accelerated approval for those 65 and older, with the accelerated approval contingent on post-marketing studies to confirm clinical benefit.
In a Phase 3 clinical trial involving more than 40,000 participants, the vaccine showed approximately 26 to 27 percent higher efficacy in preventing influenza compared to traditional standard-dose flu vaccines. Side effects including injection-site pain, fatigue, and headaches were more frequent than with traditional shots but were generally mild to moderate.
The vaccine uses mRNA technology similar to that used in COVID-19 vaccines. This platform offers a manufacturing advantage: while traditional egg-based or cell-based vaccines require strain selection roughly six months in advance, mRNA vaccines can be produced in two to three months, allowing for more precise matching against circulating viral strains.
The rollout faces complications. A federal judge has blocked the CDC's Advisory Committee on Immunization Practices from meeting due to procedural disputes, leaving the agency without its standard mechanism for issuing formal vaccine recommendations. Private insurers, Medicare, and Medicaid typically tie coverage to ACIP guidelines, creating uncertainty about whether the vaccine will be covered with zero copay.
The approval came despite a challenging political environment for mRNA technology. The Department of Health and Human Services previously canceled approximately $500 million in funding for mRNA vaccine development programs. HHS officials said mFlusiva is entering the market under stringent post-market study commitments.
