FDA to review Moderna's mRNA flu vaccine after reversing rejection

Moderna secures a formal review

The Food and Drug Administration (FDA) will now review Moderna’s mRNA-1010 flu vaccine application after previously refusing to consider the filing. The agency reversed its stance following a formal Type A meeting where Moderna proposed a new regulatory strategy to address concerns regarding trial benchmarks.

The FDA set a decision deadline of August 5, 2026, to determine if the vaccine can enter the US market. This timeline allows the agency to evaluate data from a Phase 3 trial involving nearly 41,000 adults aged 50 and older. Moderna aims to launch the product in time for the 2026 flu season, targeting older populations who are most at risk for severe complications.

Moderna CEO Stéphane Bancel confirmed the agreement on Wednesday, noting that the company modified its application to satisfy agency leadership. The reversal ends a brief but intense standoff that saw the company publicly criticize the agency's initial refusal to even open the file for review. It is a rare win for a vaccine manufacturer in an increasingly hostile political environment.

Appointees overrule the agency scientists

The initial rejection of Moderna’s application did not come from career scientists, but from Vinay Prasad, a political appointee serving as the top vaccine regulator. Prasad issued a letter on February 3 stating that Moderna’s trial design was not "adequate and well-controlled" because of the control group the company chose. Moderna used Fluarix, a standard-dose vaccine made by GlaxoSmithKline, as the comparison point for its mRNA shot.

Prasad argued that standard-dose vaccines do not represent the current "standard of care" for seniors, who typically receive high-dose or adjuvanted vaccines. However, agency records show that FDA career scientists had previously told Moderna that using a standard-dose vaccine in the trial was "acceptable." The agency’s professional staff had signed off on the trial design before the data was even collected.

Internal reports indicate that David Kaslow, a senior career official, wrote a memo urging the agency to proceed with the review. Kaslow and his team of scientists held an hour-long meeting with Prasad to defend the trial's validity. Prasad rejected their recommendations and blocked the application anyway, effectively silencing the agency's own technical experts.

Two paths for different ages

Moderna broke the deadlock by proposing a split regulatory approach for different age demographics. The company is now seeking full approval for adults aged 50 to 64, while pursuing accelerated approval for those aged 65 and older. This compromise addresses the FDA's concerns about the "standard of care" for the oldest patients without discarding the entire data set.

Under the accelerated approval pathway, Moderna can bring the vaccine to market for seniors based on its current data, provided it conducts a confirmatory trial later. This secondary trial will likely compare mRNA-1010 directly against high-dose flu vaccines to prove it offers superior or non-inferior protection. If the follow-up study fails to meet its goals, the FDA reserves the right to pull the vaccine from the market for that specific age group.

The Department of Health and Human Services (HHS) confirmed that this revised approach satisfied the agency's requirements. Spokesperson Andrew Nixon stated that the FDA will maintain its usual standards during the upcoming review process. The company’s trial data currently highlights several key metrics:

• 41,000 total participants in the Phase 3 study.
• Enrollment focused on adults aged 50 and older.
• Comparison against licensed standard-dose vaccines.
• Primary endpoints based on immunogenicity and safety profiles.
• Additional analysis provided for the 65-plus demographic.

Industry fears a chilling effect

The initial rejection of Moderna's application coincided with a broader shift in federal vaccine policy under Health Secretary Robert F. Kennedy Jr. Kennedy has been a vocal critic of mRNA technology and has installed several allies in key regulatory positions. These officials have expressed skepticism toward the rapid development cycles that characterized the pandemic response.

Moderna has already felt the financial impact of this shift, losing more than $700 million in federal contracts intended for pandemic vaccine development. Investors and industry analysts suggest that the unpredictable nature of recent FDA decisions is creating a "chilling effect" across the biotech sector. Companies are reportedly scaling back research into new immunizations due to fears that their applications will be rejected on political rather than scientific grounds.

Moderna President Stephen Hoge told The New York Times that the current environment will lead to less investment and invention across the entire industry. The message to developers is clear: even following an FDA-approved trial design is no longer a guarantee of a fair hearing. This uncertainty could delay the arrival of next-generation vaccines for various respiratory viruses.

Hostility toward mRNA technology grows

The political pressure on Moderna is expected to intensify next month when the MAHA Institute, an organization led by Kennedy, hosts an event focused on "vaccine injury." The event description claims that mRNA vaccines are linked to an epidemic of chronic illness, though these claims lack supporting evidence from major health organizations. This rhetoric is now bleeding into the formal regulatory process.

The FDA’s decision to finally review mRNA-1010 is a temporary reprieve for Moderna, but the August 2026 deadline remains a long way off. During that time, the company will have to navigate a regulatory body that is increasingly at odds with its own career scientists. The outcome of this review will likely serve as a bellwether for the future of mRNA technology in the United States.

If the vaccine is approved, it would provide a new alternative to traditional egg-based flu shots, which often have limited efficacy if the virus strains mutate during the manufacturing process. Moderna’s platform allows for faster updates to match circulating strains. For now, the company must wait to see if the science can overcome the politics.