mRNA Flu Vaccine Coming

On August 11th, the FDA (finally) approved the mRNA flu vaccine produced by Moderna. Clinical trials involving more than 40,000 subjects over the age of 50 showed that the Moderna mRNA flu vaccine (called mFlusiva), which contained copies of viral hemagglutinin sequences from 4 currently circulating strains, provided more protection than the standard egg-produced killed virus vaccine. The incidence of flu was 2% in mFlusiva recipients and 2.8% in standard-dose recipients, a statistically significant protective advantage for the mRNA formulation. In a subgroup of vaccine recipients over 65 years old, mFlusiva maintained its protective edge.

The big advantage of mRNA flu vaccines is that they can quickly be reformulated to match new flu variants. Traditional egg-produced flu vaccines take around 6 months to make, so it has been a yearly guessing game to try to match the flu sequence decided on in the spring with the flu strains causing disease in the fall.

Moderna has indicated that mFlusiva will be available for this fall flu season. Exactly when it will arrive at local pharmacies or doctor’s offices is still to be determined. The traditional flu vaccine is still pretty good, so it is the best option if mFlusiva is not available.