FDA Is Backing First-of-Its-Kind mRNA-Based Flu Vaccine

A new kind of flu vaccine moved a step closer to the US market Thursday as federal health advisers recommended approval of the first one made with the same mRNA technology that was key to ending the COVID-19 pandemic. The Food and Drug Administration is evaluating Moderna's new shot, dubbed mFlusiva, for older Americans ahead of the winter flu season. Moderna is seeking full approval for the vaccine's use in people ages 50 to 64—along with authorization for use in those 65 and older while it conducts additional testing, reports the AP. The FDA's independent advisory committee evaluated Moderna's studies of the vaccine and voted unanimously that its benefits appear to outweigh any risks for both age groups. The FDA will consider that recommendation in making a final decision by early August.

There are several types of flu vaccines already available in the US, including three specifically recommended for people 65 and older. But vaccines made with the Nobel Prize-winning mRNA technology are faster to manufacture than other types—something experts say might help if the shape-shifting flu virus mutates in a way that requires suddenly brewing new doses to match. "Having this technology available puts us in a better position to be prepared for emerging strains in the future," said Dr. Flor Munoz-Rivas of Texas Children's Hospital, an FDA adviser.

In a study of 40,000 people age 50 and older, Moderna's mRNA vaccine reduced flu cases by about 27% compared with those given another routinely used vaccine brand. In a smaller study of people 65 and older, Moderna's shot also generated a strong protective immune response compared with a high-dose flu vaccine already recommended for that age group. Data showing strong immune reactions "were very compelling," said FDA adviser Dr. Anna Durbin of Johns Hopkins University, adding that "the vaccine looks very promising." Moderna's Dr. Rituparna Das told panelists that the company's ability to quickly manufacture mRNA vaccines that closely match the latest flu strains could prevent thousands of hospitalizations in older Americans.

Severe flu cases in the US generally rise in years when the flu shot doesn't closely match the circulating viruses. Moderna officials noted that flu strains for each fall's vaccines are now chosen several months earlier than the yearly recipe update for COVID-19 shots, which mostly are mRNA-based—and there can be a mismatch if the flu virus mutates after the recipe is made. If approved, Moderna is planning its required next-step study to include 400,000 people 65 and older, half given the mRNA vaccine and the rest given one of today's special-for-seniors shots. Moderna's data showed no major safety issues, although the shot did cause temporary reactions that included injection-site pain, fever, headache, tiredness, and aches. Those temporary reactions can be a sign that "your immune system is responding," said Dr. Hayley Gans, a Stanford Medicine pediatrician and FDA adviser.