FDA reverses course and agrees to review Moderna’s mRNA flu vaccine application

The FDA reversed course and agreed to review Moderna’s application for an mRNA-based flu vaccine after last week refusing to review the filing. The regulator accepted a revised application that split the age cohorts and agreed to an additional post-market study for adults over the age of 65.

The FDA last week refused to review Moderna’s application for an mRNA-based flu vaccine, saying the study lacked a comparator arm reflecting “the best-available standard of care” for adults ages 50 and older. Yesterday, the U.S. regulator reversed course, accepting a revised application that split the age cohorts and agreed to an additional post-market study for adults over the age of 65.

The back and forth from the FDA reflects a year of turbulence under HHS secretary Robert F. Kennedy Jr., a longtime anti-vaccine activist and critic of mRNA technology, alongside Center for Biologics Evaluation and Research Director Dr. Vinay Prasad. According to one source, Dr. Vinay Prasad, the FDA commissioner’s deputy, was reported to have at times overruled or clashed with career staff in decisions involving access to new COVID-19 shots and initially declined to consider a new mRNA flu vaccine from Moderna. That decision was reversed after Moderna indicated it would challenge the decision and request intervention from the White House.

Moderna’s CEO said the turnarounds foster challenges within the biopharma industry and affect innovation. “When expectations and review timelines are unpredictable, companies face greater risk and can hesitate to invest, slowing the development of breakthrough medicines,” the CEO said on a Feb. 13 earnings call after the FDA’s initial refusal to file. “This delays patient access and increases overall healthcare costs. Sustained regulatory uncertainty frightens U.S. leadership in innovative medicines.”

For Moderna, the shift has meant shelved programs, vanished contracts and lost jobs. Other pharma companies with long-held programs in vaccines have been able to weather the storm based on the diversity of their portfolios, though vaccine sales have suffered along with fewer shots in arms in 2025.

One large vaccine maker said its Prevnar family of pneumococcal vaccines remained a major blockbuster in 2025 with almost $6.5 billion in revenue worldwide despite a 2% drop in the U.S. market. Another company said a more than 9% rise in sales of the RSV vaccine Beyfortus in 2025 gave it hope the 2023-approved shot was beginning to catch on in the market, while overall vaccine sales dropped more than a percentage point with flu, COVID-19 and other vaccines dragging down the total, and leaders expect sales to decline again in 2026. A third company said Gardasil remains important but is no longer a key growth driver and described a decline in dose recommendations by the CDC as a concern for public health more than a financial matter for the company.