Clinical Trials Show Moderna's New mRNA Flu Vaccine Is Safe and Effective. FDA Won't Even Consider It.

Since being sworn in as Health and Human Services (HHS) secretary, Robert F. Kennedy Jr has repeatedly tried to undermine public trust in vaccines. His agency recently took steps to slow down the development of these public health tools yet again.

This week, vaccine manufacturer Moderna revealed that Vinaya Prasad, the top vaccine regulator at the Food and Drug Administration (FDA)—which is a part of HHS—declined to even consider the safety and efficacy of the company’s new mRNA influenza vaccine.

The decision is not surprising, especially when one considers Kennedy’s past statements on mRNA vaccines. Nor is it surprising, given the broad discretion that the FDA has on public health. The FDA’s precautionary approach to all matters has slowed innovation in a variety of areas. In August 2025, the agency limited access to COVID-19 vaccinations (chiefly mRNA vaccines) to people aged 65 and older and to those with underlying health conditions that put them at higher risk of severe outcomes.

In his letter, Prasad claimed that the agency would not consider the merits of Moderna’s mRNA-1010 vaccine because, in its clinical trials, the company allegedly did not compare the efficacy of its vaccine with “the best-available standard of care in the United States at the time of the study.” The company actually had compared its vaccine to both a standard-dose vaccine and a high-dose vaccine, which is often recommended for people over age 65. That safety and immunogenicity study reported in March 2025 that the “findings from this phase 3 study demonstrate that mRNA-1010 elicited superior immune responses relative to licensed standard- or high-dose seasonal influenza vaccines in adults of all ages and raised no new safety concerns.”

In June of last year, Moderna reported the results of a clinical trial pitting its mRNA influenza vaccine against both high-dose and standard-dose licensed seasonal influenza vaccines. The conventional vaccines used inactivated flu viruses to induce an immune response. In the trial, the group that used Moderna’s mRNA-1010 had 26.6 percent fewer influenza cases than the group that got the standard-dose flu shot. This means that if the standard flu vaccine group had 100 cases per 1,000 people, the mRNA-1010 group would have had about 73–74 cases per 1,000. With respect to the risks of hospitalization, this level of protection is pretty comparable to conventional high-dose vaccines.

A January article in the journal npj Vaccines reported that Moderna’s mRNA flu vaccine did as well or better at inducing immune responses against flu viruses as conventional high-dose vaccines do now. The authors concluded that “mRNA-based vaccines are a promising alternative to currently licensed influenza vaccines, with the additional advantages of the mRNA technology that can incorporate rapid strain updates and a flexible manufacturing platform that could enable the production and distribution of regionally matched influenza vaccines for improved effectiveness.” In other words, mRNA flu vaccines work just as well as the most effective conventional vaccines but can be modified and manufactured more quickly to address ever-changing viruses.

In response to Prasad’s letter, The Washington Post editorial board declared, “Overzealous government agencies arbitrarily suppressing innovation is lamentable. When that innovation could save countless lives, it becomes a tragedy.”

That’s evidently a tragedy that Kennedy and his subordinates are more than willing to abet.

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