On August 5th, the FDA approved Moderna's mRNA flu vaccine — mFlusiva — for adults 50 and older. The same mRNA technology. The same age group most vulnerable to flu complications. And for Americans 65 and older, the approval came in a category called "accelerated" — which is the FDA's way of saying the evidence isn't complete yet.
They approved it anyway.
The backstory matters. In February, Vinay Prasad — then the FDA's head of biologics and an RFK ally who had been applying genuine scrutiny to new vaccine applications — issued a rare refusal-to-file notice, blocking even the review of Moderna's application. A week later, on February 18th, that decision was reversed under pressure. Prasad was gone from the agency by April 30th.
Draw your own conclusions about the sequence of events.
The accelerated approval for Americans 65 and older is the detail that deserves the most attention. It means Moderna is required to run post-market studies over two flu seasons before that approval becomes permanent. The data the FDA would normally require to protect seniors before approval doesn't exist yet. They're collecting it now — from the people who get the shot.
Brian Hooker, chief medical officer at Children's Health Defense, put it plainly: "I really believe that this technology is just too new. There has not been the adequate level of study of the implications for, you know, literally everybody."
The same concern applies here that applied to the COVID mRNA vaccines. Long-term data on repeated annual exposure doesn't exist in the literature because mRNA flu vaccines are brand new. The clinical trial showed 27% fewer flu cases in 40,000 participants across 11 countries compared to a standard shot. That's the short-term picture. The long-term picture has a two-year post-market study attached to it.
RFK spent the past year trying to apply the brakes. His HHS cancelled approximately $500 million in mRNA vaccine research funding. An HHS spokesperson offered careful framing for this approval: "Secretary Kennedy has been clear that he believes mRNA products warrant heightened scientific scrutiny. That's why this vaccine is entering the market with some of the strongest post-market study commitments FDA has required."
The strongest post-market study commitments. For a product that just received accelerated approval. For the most vulnerable age group.
One significant wrinkle: a federal judge has blocked ACIP — the Advisory Committee on Immunization Practices — from meeting, which means there may be no official federal recommendation for mFlusiva this flu season. Without that recommendation, most private insurers won't cover the shot. Its practical reach may be limited for now.
But the trajectory is set. The same technology that went from lab to arm in record time during COVID is now moving into annual flu shots for Americans 50 and older. The man who tried to stop it is gone. The approval came with conditions because the full data wasn't there. And the post-market studies meant to generate that data will use the seniors who get vaccinated this fall as the study population.
Worth knowing before you roll up your sleeve.