FDA Refuses to File Moderna’s Seasonal Influenza Vaccine Application

The FDA’s Center for Biologics Evaluation and Research (CBER) issued a refusal-to-file (RTF) letter to Moderna for its investigational influenza vaccine’s biologics license application (BLA), according to a news release.¹ Citing that the BLA does not contain a trial that is “adequate and well-controlled”—as the official letter stated—²the FDA struck down Moderna because of its choice of a vaccine comparator throughout its review.

“You can either do what’s right and give seniors the standard of care that best protects them the best, or you can kind of rig the study so it makes your product look better,” a senior FDA official told NBC News.³ “This is not a Moderna-unique issue; this is an issue that has gone on at the FDA for decades.”

Moderna’s ambition to bring the first mRNA-based influenza vaccine to the US market has hit a significant regulatory roadblock that could reshape the landscape of vaccine development. This rare move by the FDA, signed by CBER Director Vinayak Prasad, MD, MPH, means the agency will not initiate a substantive review of the BLA, despite Moderna’s use of a priority review voucher to expedite the process.^1,2,4

READ MORE: As Immunization Schedules Change, Vaccine Confidence Among Patients Falters

The FDA's decision centers on a fundamental disagreement over clinical trial design, specifically the choice of a licensed standard-dose seasonal influenza vaccine as the comparator. In the RTF letter, the agency stated that the application did not contain an adequate and well-controlled study because the control arm failed to reflect the "best-available standard of care" for the US population.¹

This is particularly relevant for pharmacists who manage vaccine inventory for seniors, as the FDA took issue with the use of a standard-dose shot for participants 65 years and older for whom high-dose vaccines are preferentially recommended.^3,4

Moderna’s Reaction to the Letter

Moderna leadership expressed shock at the rejection, arguing that the decision is inconsistent with years of previous guidance.⁴ According to the company, CBER provided written guidance in April 2024 stating that, although a preferentially recommended vaccine was suggested for older adults, using a licensed standard-dose vaccine as a comparator would be acceptable if specific language was included in the informed consent form.^1,3

Moderna maintains that the FDA reviewed and cleared the trial design 18 months ago before the study began. Company CEO Stéphane Bancel stated that the decision does not further the goal of enhancing American innovation, noting that the RTF letter did not identify any specific safety or efficacy concerns at this preliminary stage.⁴

The FDA’s Stern Stance Against Specific Vaccines

However, the FDA has since defended its stance, with officials suggesting that the choice of a “substandard” comparator may have been an intentional effort to make mRNA-1010 appear more effective.³

FDA Commissioner Marty Makary asserted that the trial design put seniors at risk of severe illness by not providing them with the current standard of care during the study.⁴ Although Moderna pointed out that 2 million US seniors still receive standard-dose vaccines annually and that many other nations do not have preferential recommendations for high-dose shots, the FDA appears to be signaling a new, aggressive phase of regulation.¹

This regulatory setback occurs amidst a broader shift in the federal government’s approach to vaccine oversight. Observers suggest the FDA may be reflecting increased skepticism of mRNA technology or implementing a strategic slowdown to evaluate long-term safety.⁴

This environment has already had financial and operational consequences for companies like Moderna, including the withdrawal of a combination flu and COVID-19 vaccine application and the cancellation of nearly $500 million in federal funding for mRNA research. Some states are even considering legislation to ban mRNA technology entirely.

For the pharmacy profession, this means that the availability of an mRNA flu vaccine in the US remains uncertain for the near future. Moderna has requested a Type A meeting with CBER to understand the path forward.¹

“This decision by CBER, which did not identify any safety or efficacy concerns with our product, does not further our shared goal of enhancing America's leadership in developing innovative medicines,” concluded Bancel in the release. “It should not be controversial to conduct a comprehensive review of a flu vaccine submission that uses an FDA-approved vaccine as a comparator in a study that was discussed and agreed on with CBER prior to starting. We look forward to engaging with CBER to understand the path forward as quickly as possible so that America's seniors, and those with underlying conditions, continue to have access to American-made innovations.”

READ MORE: Immunization Resource Center

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REFERENCES

1. Moderna receives refusal-to-file letter from the U.S. Food and Drug Administration for its investigational seasonal influenza vaccine, mRNA-1010. News Release. Moderna. February 10, 2026. Accessed February 13, 2026. https://feeds.issuerdirect.com/news-release.html?newsid=7346090610333866&symbol=MRNA

2. MRNA-biologics license application refusal to file. FDA. February 3, 2026. Accessed February 13, 2026. https://static.modernatx.com/pm/6cef78f8-8dad-4fc9-83d5-d2fbb7cff867/38ab7558-636c-40d1-b49a-c8f51a7afa1a/38ab7558-636c-40d1-b49a-c8f51a7afa1a_viewable_rendition__v.pdf

3. Lovelace Jr B. FDA defends its decision not to review Moderna’s mRNA flu shot. NBC News. February 11, 2026. Accessed February 13, 2026. https://www.nbcnews.com/health/health-news/fda-defends-decision-not-review-modernas-mrna-flu-shot-rcna258642

4. Nevradakis M. Moderna “shocked” after FDA scuttles review of new mRNA flu vaccine. Children’s Health Defense. February 11, 2026. Accessed February 13, 2026. https://childrenshealthdefense.org/defender/moderna-new-mrna-flu-vaccine-fda-declined-review-application/