Moderna's mRNA flu vaccine cleared for adults 50+, may hit pharmacies this week
The FDA approved Moderna's mRNA influenza vaccine for adults 50 to 64 and granted accelerated approval for those 65 and older. CVS and Walgreens plan to stock the shot, which clinical data suggest is more effective than standard flu shots.
Moderna's mRNA-based influenza vaccine, designated mFLUSIVA, received U.S. Food and Drug Administration approval in early August for adults aged 50 to 64, with accelerated clearance for people 65 and older. Retail chains CVS and Walgreens said the product could be available to consumers as early as this week.
Unlike traditional flu shots that rely on virus grown in chicken eggs, the mRNA vaccine delivers a short segment of genetic code that prompts the body to produce harmless viral proteins and trigger an immune response. Sonoma County health officer Dr. Mia Shim noted that while the mRNA platform is familiar from COVID-19 vaccines, this is its first use for seasonal flu inoculations.
Shim explained that the mRNA approach shortens development time, allowing manufacturers to incorporate the most recent circulating strains rather than relying on six-month-old surveillance data used for egg-based vaccines. The new shot targets three strains—H1N1, H3N2 and an influenza B lineage.
A clinical trial involving more than 40,000 adults 50 and older, published in the New England Journal of Medicine, found the mRNA vaccine reduced laboratory-confirmed flu cases by 26.6% compared with a standard-dose egg-based shot. Effectiveness gains were observed across all targeted strains, ranging from roughly 22% to 30%.
Sutter Health will continue offering its existing egg-based and high-dose options for the upcoming season, with its vaccine advisory committee slated to review the mRNA product for future formulary inclusion.
Shim cautioned that side effects such as sore arm, fatigue, headache and muscle aches occur about twice as often with the mRNA vaccine but are generally mild and resolve within one to two days. She emphasized that serious adverse events are comparable to those seen with traditional flu shots.
Public health officials continue to stress vaccination as a primary tool to reduce flu-related illness and deaths, especially among children who remain largely unvaccinated. The CDC reports that flu-related pediatric deaths over the past two decades have ranged from 37 to 297 per season, with most recent deaths occurring in unvaccinated children.
Experts recommend receiving the flu vaccine in mid-to-late October, allowing two weeks for immunity to develop before typical flu activity rises in November. Additional protective measures—hand hygiene, staying home when ill, improved indoor ventilation and mask use in crowded settings—are advised to complement vaccination.