FDA approves first mRNA flu vaccine: what mFLUSIVA means
mRNA vaccines make it possible to update shots in weeks. HHS canceled $766 million in federal funding for mRNA vaccines for pandemics.
The FDA approves Moderna’s mFLUSIVA mRNA vaccine for influenza.
On Wednesday night, the Food and Drug Administration approved mFLUSIVA, Moderna’s seasonal flu shot and the first flu vaccine built on mRNA.
August 5th was the FDA's target action date, the deadline the agency sets for itself under user-fee law.
Why did the FDA say “no” in February?
On February 10th, the FDA refused to file Moderna’s application. The objection came from Dr. Vinay Prasad, then head of the vaccine division. Moderna had tested its shot against a standard-dose flu vaccine rather than the strongest shot older adults can get.
A refusal to file is rare for a large company with a completed 40,805-person phase III trial. Eight days later, Moderna announced that it had met with the agency and that the FDA had accepted an amended application. On June 18th, the agency’s vaccine advisory committee took 2 votes, one for adults 50 to 64 and one for 65 and older. Both came back 9 to 0 in favor of approval. VRBPAC voted on whether benefits outweigh risks, not on approval. Changed to "in favor."
How well does mFLUSIVA work?
In the pivotal trial, 2.0% of people who got the Moderna flu shot got sick with the flu. Among those getting the standard-dose flu vaccine, 2.8% did. That means that there were about a quarter fewer flu cases among those getting the Moderna flu shot than those getting the standard-dose flu shot.
Side effects were about twice as high as for the standard-dose flu vaccine. Roughly two-thirds reported arm pain, 45% fatigue, and 38% headache. The FDA gave the Moderna flu vaccine full approval for adults 50 to 64. For adults 65 and older, the FDA granted accelerated approval based on immune response, but Moderna still owes the FDA a study showing the vaccine prevents illness, too.
What got green-lit, and what got cancelled?
On May 1, 2025, HHS announced Generation Gold Standard, a $500 million NIH effort to build universal flu and coronavirus vaccines out of whole killed virus. That technology is about 70 years old. The money came from Project NextGen, the Biden-era COVID vaccine program HHS had called wasteful.
Four weeks later, HHS cancelled $766 million in federal funding. That included a $590 million contract signed that January for mRNA vaccines against flu strains that could start a pandemic, including H5N1. Continued investment was "not scientifically or ethically justifiable," HHS communications director Andrew Nixon said.
And then in August, HHS Secretary Robert F. Kennedy Jr. cancelled 22 more mRNA projects at BARDA, worth about $500 million, most of them for flu and COVID. HHS has never documented where that money went. Asked, the department pointed back to Generation Gold Standard.
Will your insurance cover mFLUSIVA?
FDA approval decides whether a vaccine can be sold. Then the Advisory Committee on Immunization Practices (ACIP) determines whether insurers have to cover it for free. The exception is Medicare, for which Congress wrote influenza vaccine directly into the statute.
Under the Affordable Care Act, private plans must cover ACIP-recommended shots with no copay. That kicks in once the CDC director adopts the recommendation. Even then, commercial insurance plans aren’t required to cover the vaccines until at least a year later. The Inflation Reduction Act ties state Medicaid coverage of adult vaccines to ACIP.
ACIP has not voted on mFLUSIVA. Normally, it wouldn’t have to. Its influenza recommendation is for everyone 6 months and older gets an annual shot, using “an age-appropriate influenza vaccine,” with “no preferential recommendation” among licensed options.
On June 9, 2025, Secretary Kennedy removed all 17 sitting ACIP members and named his own. Then on March 16, 2026, Judge Brian Murphy stayed those appointments and the votes the new members had taken. He found the panel was likely seated in violation of the Federal Advisory Committee Act. HHS appealed on April 29th. The committee has had no quorum since, and its June meeting was cancelled.
So there’s no 2026-27 influenza statement. The adult immunization schedule still posted is the 2025 version. Its notes say “any influenza vaccine appropriate for age,” which should include mFLUSIVA, bu its product table lists inactivated, recombinant, and live attenuated vaccines, not mRNA.
Dr. Erica Schwartz was confirmed as CDC director 51 to 44 on August 5th, the same day the Moderna flu vaccine was approved. Adopting a recommendation is her call. A 65-year-old on Medicare Part B pays nothing either way. A 55-year-old with employer coverage or on Medicaid may be waiting on her sign-off.
The advantage of mRNA vaccine technology.
Most flu vaccine is still grown in fertilized chicken eggs. That process takes months, and it forces a strain guess long before the flu season starts. In a pandemic, it would take about 18 months to produce enough egg-based flu vaccine to cover a quarter of the world.
The advantage of mRNA vaccines is that they’re built from genetic sequences. You can redesign them and make them in weeks. That speed matters whether it’s a natural spillover event, lab accident, or bioweapon that leads to an epidemic or pandemic.
No US law requires synthetic biology companies, which make synthetic DNA and mRNA, to screen their orders for dangerous sequences. Under a 2024 White House framework, federally funded researchers can buy only from providers that agree to screen. Providers sign up voluntarily. But anyone without federal money falls outside that framework.
A 2025 study in Science tested the screening software. AI design tools produced 76,080 variants of 72 toxins and viral proteins. The software missed many of them. Developers patched it, and about 3% still get through.
On June 4th, the Foundation for American Innovation and the Institute for Progress organized a letter asking Congress for “mandatory nucleic acid synthesis screening, including recordkeeping, in the United States.” It said Congress “should act this session,” and it applauded “legislative efforts currently underway.”
“AI systems are improving rapidly, and alongside incredible benefits to science and medicine, there is a real possibility that the knowledge barriers which have historically prevented bad actors from obtaining biological weapons will meaningfully erode,” the letter said.
Signatories included Sam Altman of OpenAI, Dario Amodei of Anthropic, Demis Hassabis of Google DeepMind, and Mustafa Suleyman of Microsoft AI. Dozens of life sciences and national security experts signed, along with Eric Horvitz of Microsoft, senior author on that Science paper. Executives at Twist Bioscience and Ansa Biotechnologies signed too. Those are two of the companies the rule would cover.
If someone releases something engineered, you want a countermeasure you can redesign against a sequence in weeks. The FDA just licensed that capability for seasonal flu, but HHS has defunded it for pandemics.
Where the decisions get made.
BARDA's advanced development money is a congressional appropriation. It runs through the Labor-HHS subcommittees, chaired by Rep. Robert Aderholt (R-AL) in the House and Sen. Shelley Moore Capito (R-WV) in the Senate. Sen. Tammy Baldwin (D-WI) is the ranking Democrat there, and Sen. Patty Murray (D-WA) sits on the subcommittee while serving as vice chair of the full Senate committee. In the House, Rep. Tom Cole (R-OK) chairs full Appropriations and Rep. Rosa DeLauro (D-CT) is its ranking Democrat. Aderholt's FY2027 bill adds $105 million for medical countermeasures, but doesn't mention mRNA vaccines.
Insurance coverage depends on the First Circuit Court of Appeals, which is deciding whether Brian Murphy, U.S. District Judge for the District of Massachusetts, was right to block Secretary Kennedy's ACIP appointees. That ruling settles will determine who sits on the committee. The CDC director can then adopt the recommendation or not.
Senators Tom Cotton and Amy Klobuchar introduced the Biosecurity Modernization and Innovation Act on February 4th. It would direct the Commerce Department to require gene synthesis providers to screen their orders and their customers.