With a panel of outside experts set to weigh in Thursday—and with a refusal-to-file fiasco with the FDA just barely in the rearview—Moderna and its contender for the United States’ first mRNA-based influenza vaccine are heading into a critical test this week.
Still, documents released Tuesday ahead of a Jun. 18 meeting of the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) bode well for Moderna’s mFlusiva, especially in light of the brief application impasse earlier in 2026.
Experts from VRBPAC are tasked with voting (PDF) on two questions Thursday, focused on the risk-benefit profile of mFlusiva for influenza prevention in adults between the ages of 50 and 64 years, as well as in the 65-years-and-older crowd.
The FDA uses advisory committee meetings to seek outside counsel on tough or high-profile regulatory decisions. The agency isn’t beholden to the vote results, though the FDA often follows the opinions of its panels.
Adding uncertainty to the fate of mFlusiva is the refusal-to-file (RTF) letter that Moderna received earlier this year. In the letter, the agency’s Center for Biologics Evaluation and Research (CBER)—then under the controversial stewardship of Vinay Prasad, M.D.—raised issues with the control arm in Moderna’s phase 3 vaccine trial, arguing that the standard-dose seasonal flu vaccine used in the comparator arm did not represent best available standard of care for older adults.
Nevertheless, the FDA’s view on mFlusiva’s approvability now appears more “balanced,” or “not harsh,” on the whole, Jefferies analyst Andrew Tsai wrote to clients in a June 16 note.
In summarizing its concerns and the reason for the meeting, the FDA noted in briefing documents (PDF) that on effectiveness, “[n]o major deficiencies were identified” and that mFlusiva also met all pre-specified criteria for success—noninferiority, superiority and super-superiority—relative to the standard-dose comparator shot.
Still, the regulator is asking the VRBPAC members to explore whether that standard-dose control was really the best comparator for Moderna’s purposes, citing the treatment preference of a high-dose, recombinant or adjuvanted flu shot in patients ages 65 years and older.
Other factors up for consideration are the “interpretive uncertainty” in relative vaccine efficacy against influenza B/Victoria over low case accrual, the adequacy of a single-season efficacy data in the study population Moderna recruited and whether using immunogenicity as a surrogate endpoint is a reasonable weathervane for mFlusiva’s clinical benefit in the older patient population.
Moderna’s primary efficacy study for mFlusiva, coded mRNA-1010-P304, enrolled nearly 41,000 participants across 301 sites in North America, Europe and East Asia, the FDA noted in its review materials. The trial ran during the 2024-2025 Northern Hemisphere influenza season, comparing Moderna’s mRNA vaccine to either a standard-dose trivalent or quadrivalent flu vaccine.
To address FDA concerns, Moderna has proposed a bifurcated regulatory pathway, seeking traditional approval for adults between the ages of 50 and 64 years and an accelerated nod in those 65 and older. Were it to win that accelerated green light on an immunogenicity surrogate endpoint, Moderna would commit to running a confirmatory trial for mFlusiva in the older patient group.
The FDA’s position appears to reflect “a change in response to this specific application from a few months ago and let us hope more generally with respect to vaccines,” former FDA chief scientist Jesse Goodman told Reuters on Tuesday.
Investors appeared to react warmly to the FDA’s stance in the documents. Moderna’s stock was trading up about 8% as of mid-afternoon on Tuesday, June 16.
Early this year, after the FDA snubbed its application attempt, Moderna published the RTF letter and immediately took issue with the fact that the FDA’s decision seemed to contradict prior discussions between the two. At the time, the mRNA specialist’s CEO, Stéphane Bancel, argued that the move did “not further our shared goal of enhancing America's leadership in developing innovative medicines."
The decision immediately proved controversial and seemed to confound fears about an increasing anti-vaccine bent under a Robert F. Kennedy Jr.-led health department.
Since then, both Prasad and Trump administration-appointed FDA commissioner Martin Makary, M.D., have hit the exit, alongside many other political appointees at the regulator, with reports mounting in recent months that the White House has grown frustrated by the unpopular optics of an anti-vaccine ethos at the FDA and beyond before midterm elections this fall.
Following the public fallout, the FDA reversed course days later, accepting a revised influenza filing from Moderna and setting the shot on course for a potential approval in time for the 2026-27 flu season.
The FDA currently aims to make an approval decision on mFlusiva by Aug. 5.
Moderna’s future hinges on the success of several near-term potential launches, with mFlusiva expected to lead that charge. The company is also hoping to secure clearance for a combination flu and COVID shot and a seasonal vaccine for norovirus within the 2027-28 timeframe.
In a bid to get its commercial house in order, Moderna on Tuesday morning revealed that it has hired Novartis and BMS veteran Ester Banque to fill the role of chief commercial officer. Meanwhile, company president Stephen Hoge, M.D., is having his responsibilities expanded to oversee each of the company’s three divisions: commercial, manufacturing and R&D.