First mRNA Flu Vaccine Arrives as Flu Season Gets an Early Start

The first mRNA-based flu vaccine licensed in the United States is arriving at pharmacies and clinics just as flu season appears to be starting early. The US Food and Drug Administration approved Moderna’s mFLUSIVA on Aug. 5 for adults 50 and older.

The FDA’s vaccines advisory committee voted unanimously that the shot’s benefits outweigh its risks. Moderna called the vaccine its fourth approved product in the United States, according to CNN.

For adults ages 50 through 64, the approval rested on a Phase 3 trial of 40,805 adults in 11 countries, according to The Educated Patient. The mRNA shot showed 26.6 percent relative efficacy compared with a standard-dose flu vaccine, meaning it prevented roughly a quarter more flu infections.

Approval for adults 65 and older came through an accelerated pathway. That decision was based on a trial of 2,992 US adults that measured immune response against a high-dose inactivated flu vaccine rather than counting prevented infections, and a confirmatory trial is still to come.

The shot is now available at more than 13,000 locations across the country, according to Moderna. CNN reported that Walgreens is offering it in limited quantities and CVS is providing it to adults 50 and older upon request in selected areas.

More than 75 percent of positive flu tests in the last month were for H1N1, and experts are urging people to get vaccinated earlier than usual, according to the New York Post.

The vaccine contains no egg protein, preservatives or antibiotics. Side effects such as injection site pain, fatigue and headache were reported more often than with conventional shots but were generally mild, lasting a median of two days, according to Immunize.org.