FDA Reverses Moderna Flu Vaccine Decision, Drops Two-Study Drug Approval Requirement

The Food and Drug Administration has reversed course and agreed to review Moderna's application for the first mRNA-based flu vaccine under a revised approach, the company announced Wednesday. Moderna received a Prescription Drug User Fee Act (PDUFA) goal date of Aug. 5, 2026, with the vaccine potentially available for U.S. adults 50 and older for the 2026-2027 flu season.

After receiving a Refusal-to-File (RTF) letter from the FDA, Moderna scheduled a Type A meeting and proposed a revised regulatory approach for the vaccine. The proposed pathway was based on age, seeking approval for adults 50 to 64 years old and accelerated approval for adults 65 and older, with a post-marketing requirement to conduct an additional study in older adults. The company met with the FDA and the agency agreed to review the vaccine after Moderna agreed to conduct an additional study in older people.

RTF letters are rare; according to a 2021 study of 2,475 applications, only 4% received an RTF letter. Additionally, Type A meetings are reserved for urgent issues. When a request for a Type A meeting is submitted, the FDA is required to respond within 14 days, and, if granted, schedule the meeting within 30 days. Moderna requested a meeting only eight days ago.

The FDA originally refused to review the submission due to a dispute over Moderna's trial design. The issue centered on the comparator arm, where Moderna used a standard flu vaccine rather than a high-dose or adjuvanted vaccine that is preferentially recommended for adults 65 and older. Moderna acknowledged that while the FDA recommended including the vaccine in its trial, the agency did not indicate it would refuse to review the mRNA vaccine if the trial proceeded as planned.

Separately, the Food and Drug Administration plans to drop its longtime standard of requiring two rigorous studies to win approval for new drugs. Going forward, the FDA's "default position" will be to require one study for new drugs and other novel health products, the FDA Commissioner and a top deputy wrote in a New England Journal of Medicine piece published Wednesday.

The announcement is the latest example of changing longstanding FDA standards and procedures with the stated goal of slashing bureaucracy and accelerating the availability of new medicines. Since arriving at the agency last April, the FDA Commissioner has launched a series of directives that he says will shorten FDA reviews, including mandating the use of artificial intelligence by staffers and offering one-month drug assessments for new medications that serve "national interests."

In their piece published Wednesday, FDA officials state that dropping the two-trial requirement reflects modern advances that have made drug research "increasingly precise and scientific." "In this setting, overreliance on two trials no longer makes sense," they write. "In 2026 there are powerful alternative ways to feel assured that our products help people live longer or better than requiring manufacturers to test them yet again." The FDA officials predicted the shift would lead to "a surge in drug development."

The FDA's former drug director said the change makes sense and reflects the FDA's decades-long move toward relying on one trial, combined with supporting evidence, for various life-threatening diseases, including cancer. "The scientific point is well taken that as we move toward greater understanding of biology and disease we don't need to do two trials all the time," said the former director, who led the FDA's drug center for about 20 years before retiring in 2024.

The two-study standard for drugs dates to the early 1960s, when Congress passed a law requiring the FDA to review data from "adequate and well-controlled investigations," before clearing new medications. For decades, the agency interpreted that requirement as meaning at least two studies, preferably with a large number of patients and significant follow-up time. The reason for requiring the second study was to confirm that the first trial's results weren't a fluke and could be reproduced.

But beginning in the 1990s, the FDA increasingly began accepting single studies for the approval of treatments for rare or fatal diseases that companies often struggle to test in large numbers of patients. Over the last five years, roughly 60% of first-of-a-kind drugs approved each year have been cleared based on a single study. The shift reflects laws passed by Congress that directed regulators to be more flexible when reviewing drugs for serious or hard-to-treat conditions.

The new policy announced Wednesday will mainly impact drugs for common diseases that previously weren't eligible for reduced testing standards. "It's not the cancers and the rare diseases that will be affected by this," the former drug director noted. "The agency has been approving those on a single trial already."

The latest approach from FDA leadership contrasts with the agency's recent actions on vaccines, gene therapies and other treatments. The FDA's vaccine division has rejected a string of experimental gene therapies and biotech drugs, citing the need for additional studies or more definitive evidence. The trend has weighed on the stocks of many biotech companies and clashed with public statements promoting the speed and flexibility of the FDA's reviews.

The former drug director said the drug industry will have to wait and see whether the FDA's approach to promising experimental therapies changes. "Implementation will be everything," she said. "Since the agency's approach is unclear, and the industry is already baffled, I don't think this adds any illumination."

MRNA vaccines are faster to develop than traditional vaccines. As of 3:30 PM EST on February 18, Moderna shares were up 5.74 percent on the day, rising $2.52 to $46.45.