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.

However, on 18 February 2026, the FDA reversed itself and will review the Moderna BLA after a meeting with company officials. This does not mean that it will approve the vaccine — it just means that it will review it under new conditions.

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

FDA refusal to review 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.

FDA reverses course and accepts modified Moderna application for mRNA flu vaccine

On 18 February 2026, Moderna announced that, in response to a prior Refusal-to-File (RTF) letter, the company engaged with the FDA in a Type A meeting and proposed a revised regulatory approach for mRNA-1010.

To advance the review, Moderna proposed a regulatory pathway based on age, seeking full approval for adults 50-64 and accelerated approval for adults 65 and older, along with a post-marketing requirement to conduct an additional study in older adults.

Following submission of the amended application, the FDA accepted the Moderna BLA for review and assigned a Prescription Drug User Fee Act (PDUFA) goal date of 5 August 2026, with approval possibly in time for the 2026-27 flu season.

What does this all mean?

This is better news than what I reported earlier, when it appeared that the FDA would not review the Moderna mRNA-based seasonal flu vaccine biologics licence application.

However, 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. Just because the FDA is going to review the revised application, I remain skeptical that it will approve any mRNA-based vaccine. Our inability to provide “good faith” to RFK Jr’s decisions on vaccines means it’s hard to tell whether this decision on Moderna’s vaccine is deserved (and it may well be), the start of a long-term strategy against mRNA vaccines, or even all vaccines.

On the surface, this may not seem important since the Moderna mRNA-based seasonal flu vaccine is not a large 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.

At any rate, it’s good news that the FDA reversed its initial decision and will review the Moderna mRNA-based seasonal flu vaccine with new indications. I’m cautiously optimistic that the FDA will approve this new vaccine, but I remain wary.

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