FDA Reverses Course, Will Review Moderna's mRNA Flu Vaccine

The U.S. Food and Drug Administration will review a messenger RNA (mRNA) flu vaccine for approval, according to its maker, Moderna. The decision is a dramatic U-turn for the agency, which, only about a week ago, had publicly rejected Moderna’s application to get the shot reviewed.

When it initially rejected the application, the FDA had said Moderna’s clinical trials were lacking. On Wednesday, Moderna said it had made modifications to its application.

While the reversal has been welcomed by the vaccine maker and public health experts alike, the incident has been the latest instance of the Trump administration undermining vaccine science. Secretary of Health and Human Services Robert F. Kennedy, Jr., whose department has jurisdiction over the FDA, is a noted vaccine skeptic who has repeatedly criticized mRNA COVID vaccines.

HHS spokesperson Andrew Nixon said in a statement that the FDA had held discussions with the company, leading to “a revised regulatory approach and an amended application, which FDA accepted.” “FDA will maintain its high standards during review and potential licensure stages as it does with all products,” Nixon said.

William Schaffner, an infectious disease physician and a professor at Vanderbilt University Medical Center, says the FDA’s decision to backtrack is “good news.” “It is important to give all candidate new vaccines a fair equitable assessment. This is especially true for new mRNA-based vaccines as this technology currently is being applied to create vaccines against a variety of illnesses, including cancers," he says.

Modern’s mRNA flu shot is based on the same technology as its COVID vaccine. The mRNA COVID shots have been credited with saving millions of lives. “With these mRNA vaccines, the benefits outweigh the risk,” says Angie Rasmussen, a virologist at the University of Saskatchewan.

In these kinds of shots, mRNA—essentially the instruction manual for genes to make proteins—is injected into the body, where it teaches cells to recognize and attack viral proteins. Vaccines that use mRNA are attractive prospects for protecting against flu and a host of other diseases, including cancer. They are easy to manufacture quickly and highly flexible, meaning new vaccines can be made rapidly to respond to emerging viral variants.

Having such a vaccine available for flu would “potentially be a major step forward in efforts to protect the health of individuals from severe influenza,” says Robert Hopkins, medical director of the National Foundation for Infectious Diseases.