On 10 February 2026, Moderna announced that the US Food and Drug Administration (FDA) refused to review its biologics license application (BLA) for its mRNA-based flu vaccine. Without a review and approval of its BLA, Moderna will not be able to market its new flu vaccine in the USA, although other countries may still review and approve it.

This is just another method from the anti-vaccine sycophants of HHS Secretary Robert F Kennedy Jr to disrupt and damage the vaccine system of the USA. I think this is just the first shot by RFK Jr to end approvals for new vaccines, unless those vaccines’ BLAs meet some ridiculous and unscientific standards for approval.

Let’s look at what happened here and what it portends for the future of vaccine development in the USA.

FDA refusal of Moderna BLA for mRNA flu vaccine

Just for a quick review, the biologics license application is the last step of the vaccine development process. After preclinical studies to determine if a new vaccine might work, Moderna and other vaccine manufacturers file an Investigational New Drug (IND) application to the FDA’s Center for Biologics Evaluation and Research (CBER) to begin clinical trials.

Moderna included over 40,000 individuals in three phases of clinical trials for the new mRNA-based seasonal flu vaccine, designated mRNA-1010. The study compared the safety and effectiveness of mRNA-1010 against other seasonal flu vaccines currently on the market.

That trial concluded the new vaccine was somewhat more effective in adults 50 and older than the standard flu vaccine. So, mRNA-1010 is not a great technological advance over other flu vaccines, but mRNA technology might allow Moderna to develop a revised flu vaccine against new flu strains quickly.

In the letter to Moderna, FDA vaccine director Vinay Prasad, MD, MPH, said that he doesn’t consider the application to contain an “adequate and well-controlled trial” because it didn’t compare the new shot to “the best-available standard of care in the United States at the time of the study.”

Even though I disagree with Prasad’s decision, the FDA under President Joe Biden advised Moderna to revise its clinical trial for the vaccine, but they didn’t make any changes. The FDA agreed to let the study proceed as originally planned without the recommended changes. Basically, Biden’s FDA wanted Moderna to compare the safety and effectiveness of mRNA-1010 against the high-dose flu vaccines recommended for seniors.

Moderna said it had shared with the FDA additional data from a separate trial comparing the mRNA-1010 against a licensed high-dose vaccine used for seniors.

For decades, the FDA has allowed vaccine manufacturers to quickly update their annual flu vaccine to target the latest strains by showing that they trigger an immune response in patients. That’s a far more efficient approach than running long-term studies tracking whether patients get the flu and how they fare.

What does this all mean?

On the surface, this may not seem important because the Moderna mRNA-based seasonal flu vaccine is not a big leap in flu vaccine safety and effectiveness. We are waiting for new universal flu vaccines that might work across several years, lessening the need for an annual flu jab.

However, the FDA and Prasad’s decision not to review this application is more troubling than it seems. FDA approval of new flu vaccines has got to be speedy and efficient because new strains of the flu appear annually, so new vaccines need to get to market before the flu season starts. Flu vaccine manufacturers generally have about six months from the decision on which flu virus strains are circulating to produce a new vaccine.

Of course, the anti-vaccine FDA wouldn’t even review the BLA, so Moderna didn’t have a chance to address any questions about it. And Moderna will probably have little opportunity to market the vaccine in the USA.

If this refusal had been made during other Presidents and HHS Secretaries, we would just assume there was a problem with the application and barely notice the action.

Given RFK Jr’s attacks on mRNA-based vaccines in general, I am generally worried that the USA will fall behind on numerous promising mRNA-based vaccines and cancer treatments. Our inability to provide “good faith” to RFK Jr’s decisions on vaccines means that it’s hard to tell if this decision on Moderna’s vaccine is deserved (and it may well be), or the start of a long-term strategy against mRNA vaccines, or even all vaccines.

What worries me most is that the damage to the vaccine system in the USA will be so great that it could take years, or even decades, to repair it if a more science-based administration takes over the reins eventually. It’s making me lose sleep.

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