US regulators recently decided not to review Moderna’s request for a new flu vaccine that uses messenger RNA (mRNA) technology. This choice has stirred concerns about future vaccine development in the US. Just last year, the FDA had seemed supportive of the project.
Since January, the Trump administration has shifted its stance on vaccines, choosing not to fully recommend one-third of routine childhood vaccines, including those for the flu. Dorit Reiss, a law professor at UC San Francisco, noted that this could deter investment in new flu vaccines and complicate the relationship between the pharmaceutical industry and the FDA.
mRNA vaccines have shown great promise. They can be updated quickly to match evolving flu strains, which is crucial given how fast the virus changes and its potential pandemic threat. However, the FDA has declined to assess Moderna’s clinical trial results because they compared the new vaccine against standard flu shots rather than those specifically for high-risk groups.
In a letter from Vinay Prasad, director of the FDA’s Center for Biologics Evaluation and Research, he argued that this type of comparison wasn’t sufficient. However, it’s worth noting that Moderna did compare their vaccine to a higher-dose flu shot for older adults and to standard shots for those under 65. Reiss pointed out that this comparison is valid, suggesting the FDA’s reasoning may be flawed.
Interestingly, data from the trial showed the new vaccine produced better antibody responses without any safety issues. There is also another trial that compared the vaccine to standard shots for adults aged 50 and older, though results from that trial haven’t been published yet.
The situation got more complicated when the FDA issued a “refusal-to-file” letter, which means they won’t consider the licensing application until they receive more information from Moderna. This letter was rather unusual because it’s usually the review team that makes these decisions, not the CBER director.
While no official changes were announced about conducting vaccine trials, internal communications leaked last November suggested the FDA was planning to revise the criteria for flu vaccine efficacy tests.
The Department of Health and Human Services (HHS) didn’t clarify whether FDA rules had changed or if this decision indicated a broader policy shift away from approving flu vaccines for the general population.
Moderna’s CEO, Stéphane Bancel, responded to the refusal, emphasizing that no safety concerns had been raised regarding the vaccine and that it should be routine to review a flu vaccine submission.
Despite these challenges, the licensing application is still under review in the EU, Canada, and Australia. These developments have fueled discussions on social media about vaccine accessibility and government transparency, with many advocates pressing for clearer guidelines.
In January, HHS also altered its recommendations for children’s flu shots, now suggesting they only be given under “shared clinical decision-making” without broader public consultation. This decision has raised additional questions about the future of vaccine policies in the US.
For more detailed insights on vaccine approval processes, you can visit CDC.
