FDA Reverses Course, Will Review Moderna’s mRNA Flu Vaccine Application

The US Food and Drug Administration (FDA) has reversed its previous decision and will now review Moderna’s application for an mRNA-based influenza vaccine for adults aged 50 and older. This reversal comes just one week after the agency initially refused to review the application, raising concerns within the pharmaceutical industry and among public health experts.

The FDA’s initial refusal to file the application stemmed from concerns about the design of Moderna’s Phase 3 clinical trial. Specifically, the agency questioned the use of a standard-dose flu shot in the control group for participants aged 65 and older, suggesting a high-dose vaccine would have been more appropriate. Moderna maintained that the FDA had previously approved the trial design and that there were no safety or efficacy concerns with the mRNA-1010 vaccine candidate.

The amended application now seeks full FDA approval for adults aged 50 to 64 and accelerated approval for those 65 and older. Accelerated approval will be contingent upon a post-marketing study to further evaluate the vaccine’s effectiveness in the older age group. The FDA has set a target date of August 5, 2026, for completing its review, potentially allowing the vaccine to be available before the next flu season.

“We appreciate the FDA’s engagement in a constructive Type A meeting and its agreement to advance our application for review,” said Stéphane Bancel, CEO of Moderna, in a statement. “Pending FDA approval, we look forward to making our flu vaccine available later this year so that America’s seniors have access to a new option to protect themselves against flu.”

The initial rejection of Moderna’s application sparked considerable debate and raised questions about potential shifts in US vaccine policy under the current administration. The FDA, under the leadership of Health and Human Services Secretary Robert F. Kennedy Jr., has significantly reduced funding for mRNA vaccine development, cutting $500 million in contracts last August. Kennedy has long been a vocal critic of mRNA vaccines, including those developed during the COVID-19 pandemic.

This funding reduction and the initial rejection of Moderna’s flu vaccine application led to anxieties within the vaccine manufacturing sector. Reports indicated that companies, including Moderna, were beginning to cut jobs and scale back research operations in the United States, anticipating a potentially less supportive regulatory environment.

The reasons behind the FDA’s reversal remain unclear. Infectious disease expert Michael Osterholm, PhD, MPH, director of the University of Minnesota’s Center for Infectious Disease Research and Policy, expressed confusion, stating, “We don’t have any idea why they reversed course. That’s part of the problem.” Osterholm emphasized the need for consistent policy and clear guidelines for vaccine developers, stating, “They need to know what is needed for approval, and how it would be supported after approval. Without that we will see a rapidly changing vaccine landscape.”

Osterholm further commented that the current situation “demonstrates how out of control we are in the FDA’s consideration and review of currently licensed vaccines and potential new vaccines.”

Robert H. Hopkins Jr., MD, medical director of the National Foundation for Infectious Diseases, expressed optimism about the FDA’s decision to review the application. “It is hard to assess whether This represents an indication of changes in agency leadership’s approach to new vaccine applications or not; but I am hopeful that it does,” Hopkins said. He highlighted the potential benefits of having another influenza vaccination option, particularly one utilizing mRNA technology, which allows for more rapid adaptation to evolving viral strains compared to traditional vaccine manufacturing processes.

The development of an mRNA-based flu vaccine represents a significant advancement in vaccine technology. MRNA vaccines offer the potential for faster development and production, allowing for quicker responses to emerging viral threats and the ability to tailor vaccines to specific circulating strains. The current influenza vaccines require several months to produce, relying on egg-based manufacturing processes. An mRNA vaccine could potentially be updated and manufactured more rapidly, offering a more effective defense against seasonal influenza.

While the FDA’s review is underway, the availability of a new flu vaccine option remains uncertain. However, the agency’s decision to reconsider Moderna’s application is a positive step towards potentially expanding the tools available to protect the public against influenza. The outcome of the review will be closely watched by the medical community and public health officials alike.