🧠 FDA to review Moderna flu shot built on COVID-19 mRNA

The FDA said it will review Moderna’s application for the first mRNA flu shot after initially issuing a refuse-to-file letter — a reversal that hinges on Moderna agreeing to a post-market confirmatory study in older adults using a high-dose comparator.

The move

• The Food and Drug Administration reversed course Wednesday and said it would review Moderna’s application after earlier saying it wouldn’t even look at it.

• FDA Commissioner Marty Makary signaled the refuse-to-file letter was part of an iterative process between the agency and the company.

• HHS spokesman Andrew Nixon said FDA met with Moderna and the company amended its application; FDA then accepted it for review.

Why it Matters for Care

• If approved, clinicians could see a new influenza vaccine platform: Moderna’s flu shot built on the COVID-19 mRNA approach the company used to rapidly develop and manufacture its pandemic vaccine.

• The key clinical sticking point is evidence in older adults: FDA wanted comparative safety/efficacy data versus a CDC-recommended high-dose flu vaccine, given higher risk and different immune responses in this population.

• Moderna now says it will run a confirmatory study in older adults after the vaccine is on the market — raising the practical question of how quickly definitive comparative data will arrive relative to adoption.

Between the Lines

• This is a high-stakes signal to industry about regulatory predictability: Moderna says FDA agreed to the trial design 18 months ago, while HHS says the company didn’t follow 2024 guidance on the comparator.

• Health economist Rena Conti (Boston University) warned the back-and-forth fits a pattern of “chaotic decision-making,” which can chill long-horizon vaccine investment.

• Moderna has put over $1B into the program, including up to $750M from Blackstone — creating pressure for a timely pathway while FDA emphasizes “high standards” for licensure.

What to Watch

• FDA’s review outcome and timing — and whether the agency adds conditions or requires more pre-licensure comparative data for older adults.

• Details of the post-market confirmatory trial (design, endpoints, timelines) and how results may affect labeling, recommendations, and uptake.

• Whether the vaccine can realistically be cleared in time for the next flu season, as Moderna claims, pending FDA approval.

Source: NPR Health