FDA panel backs first-of-its-kind flu vaccine using mRNA technology

WASHINGTON (AP) — A new kind of flu vaccine moved a step closer to the U.S. market Thursday as federal health advisers recommended approval of the first 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.

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.

Tens of thousands of Americans die from influenza every year, and older adults are among the most vulnerable. There are various types of flu vaccines already available in the U.S., 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, one of FDA's advisers.

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 U.S. generally rise in years when the flu shot doesn’t closely match the circulating virus. Moderna officials noted that flu strains for each fall's vaccines now are chosen several months earlier than the yearly recipe update for COVID-19 shots that mostly are mRNA-based — and there can be a mismatch if the flu virus mutates after the recipe is made.

At the meeting, FDA vaccine reviewer Dr. Timothy Brennan suggested the agency was open to approving the vaccine for older adults ahead of the coming flu season, despite the need for more information about its use in frail seniors or people with weak immune systems.

If it's 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. It's supposed to repeat that study for two flu seasons.

Moderna's data showed no major safety issues although the shot did cause some temporary reactions including injection-site pain, fever, headache, tiredness and aches. The latter reactions are common in a variety of vaccines, but occurred somewhat more often than with today's flu shots. The FDA said that's typical of mRNA vaccines.

Those temporary reactions can be a signal that “your immune system is responding,” said Dr. Hayley Gans, a Stanford Medicine pediatrician and FDA adviser who stressed it will be important to explain that to vaccine recipients.

Earlier this year, Moderna’s data was at the center of a highly unusual public dispute as a then-top FDA official blocked the company’s application for its first-of-its-kind shot.

The embattled vaccine chief at the time, Dr. Vinay Prasad, said the company should have compared its shot to a high-dose flu vaccine recommended for seniors rather than a standard-dose brand. It was a sign of FDA’s heightened vaccine scrutiny under Health Secretary Robert F. Kennedy Jr.

Moderna challenged that decision, noting that FDA staff had approved that main study’s design and citing a separate, smaller study comparing the mRNA shot with a high-dose vaccine for seniors. Days after the spat, the FDA accepted Moderna’s application.

Moderna also is studying the vaccine in younger adults and plans a separate study in 9- to 17-year-olds this fall.

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