FDA U-turn lets Moderna’s mRNA flu shot into the review pipeline

CBS News, Axios, the New York Times, CNBC, and CNN contributed to this report.

Moderna just dodged what looked like a major regulatory roadblock.

On Wednesday the biotech said the US Food and Drug Administration has reversed course and will review its application for an mRNA seasonal flu vaccine candidate called mRNA-100. That’s a big pivot: last week the agency sent Moderna a rare “refusal to file” letter, effectively tossing the company’s submission back to the bench. Now, after a face-to-face Type A meeting and an amended filing, the FDA has accepted the revised approach for review.

Why the flip? It boiled down to trial design. The controversy centered on a 40,000-person Phase 3 study that showed Moderna’s shot worked well in adults 50 and older compared with a standard flu vaccine. FDA vaccine director Dr. Vinay Prasad objected that Moderna didn’t use the highest-dose vaccine recommended for people 65+, and flagged the control arm as not reflecting the “best-available standard of care” for older adults. That prompted the refusal to file.

Moderna pushed back, saying the company’s original plan had been discussed with regulators and that the control it used — widely distributed Fluarix Quadrivalent by GSK — was acceptable. After talks, Moderna and the FDA struck a compromise: the company will seek full approval for people aged 50–64 and an accelerated approval for those 65 and up, while committing to run another study comparing the shot to a higher-dose or similar vaccine in older adults after it’s on the market.

“Pending FDA approval, we look forward to making our flu vaccine available later this year so that America’s seniors have access to a new option to protect themselves against flu,” Moderna CEO Stéphane Bancel said in a statement.

HHS confirmed the swap. Andrew Nixon, a spokesperson for the Department of Health and Human Services, called the meeting “constructive” and said discussions “led to a revised regulatory approach and an amended application, which FDA accepted.” He added that the agency will “maintain its high standards during review and potential licensure stages as it does with all products.”

Practical upshot: the FDA has set an internal target — August 5 — to decide whether to approve the shot in time for the 2026–27 flu season. Moderna says it plans to make the vaccine available for adults 50 and older if it gets the green light.

Investors liked the news. Moderna shares jumped roughly 6% in midday trading.

No mRNA flu vaccine has been licensed anywhere yet. If Moderna clears the bar, it would be the first. The tech itself—mRNA—earned its stripes during the Covid pandemic, but it’s come under fresh scrutiny lately. The US health-policy environment has shifted; some senior officials have openly criticized mRNA platforms, and Health Secretary Robert F. Kennedy Jr. has been vocal about safety concerns. That political backdrop made Moderna’s initial refusal especially noisy and sent ripples through the vaccine industry.

Executives and industry groups slammed the perceived inconsistency. Moderna’s president, Dr. Stephen Hoge, told interviewers that regulators must be predictable: changing the rules after trials are designed “isn’t something you can have.” BIO, the biotech trade group, called the FDA’s decision to review the vaccine “absolutely right” for innovation.

What to keep an eye on next:

• The FDA’s review timeline and whether August 5 sticks. If it approves the shot, rollout could be fast.
• The post-market study Moderna must run in 65+ adults: who pays for it, how it’s designed, and whether real-world data backs the vaccine’s benefits.
• International regulators: Europe, Canada and Australia are also reviewing the candidate, and their decisions will matter for global uptake.
• The political noise. Shifts at HHS and the agency’s top leadership have put extra spotlight on vaccine approvals; that could shape how strictly regulators parse trial design down the road.

Moderna’s application is back in play after a dramatic back-and-forth. The fix is procedural for now—reframe the filing, add a post-market study—rather than a wholesale cure for the uncertainty that’s been dogging mRNA development under current policy winds. The industry will be watching closely: an approval would be a milestone for mRNA beyond Covid, but the way this episode unfolded highlights how fragile the path to market can be when science, policy and politics collide.