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

In a regulatory turnaround, the FDA will now review Moderna’s seasonal mRNA flu vaccine application after initially issuing a rare refusal-to-file letter earlier this month.¹ The agency’s reversal—driven by further discussions with the company and a revised regulatory pathway—means Moderna’s application for a novel influenza shot could be evaluated in time for the 2026-2027 flu season.

Moderna’s investigational vaccine, known as mRNA-1010, demonstrated superior efficacy in a phase 3 trial (NCT05415462) involving more than 40,000 adults 50 years and older compared with a standard licensed influenza vaccine. Moderna submitted the biologics license application (BLA) seeking full approval for adults ages 50 to 64 years and accelerated approval for those 65 years and older, with a postmarketing study required for the older age group. The FDA has set an internal Prescription Drug User Fee Act (PDUFA) goal date of August 5, 2026, to complete its review.

The decision to accept Moderna’s amended submission follows a public dispute between the company and the FDA. Earlier refusal stemmed from FDA concerns that Moderna’s pivotal study did not compare the vaccine against the highest-dose flu vaccines recommended for older adults, which regulators argued would have better represented the best available standard of care for that population. Moderna countered that the initial study design had been discussed in prior consultations with the FDA and that no safety or efficacy concerns were raised prior to submission.

This episode has reignited broader debate about the regulatory environment for mRNA-based vaccines, as critics argue that restrictive approaches could slow innovation in next-generation vaccine development. The initial refusal came amid heightened FDA scrutiny of mRNA technologies under current federal leadership, including actions by HHS Secretary Robert F. Kennedy Jr, who has publicly challenged certain aspects of mRNA vaccine policy.

Patent Dispute Adds Legal Pressure for Moderna

Meanwhile, Moderna is confronting legal headwinds unrelated to its influenza program. In a separate matter, US District Court Judge Joshua D. Wolson ruled that the company is barred from asserting several key defenses in a patent infringement lawsuit brought by Arbutus Biopharma Corp. and Genevant Sciences GmbH over technology used in Moderna’s COVID-19 vaccines.² In a decision issued earlier this week, the court granted in part Arbutus’ motion for summary judgment, effectively precluding Moderna from arguing that certain patents held by Arbutus are obvious or that one invention was not Arbutus’ own, tightening the company’s legal position before the case proceeds to a jury trial. The ruling bars Moderna from asserting obviousness and derivation defenses with respect to US patents 9,364,435, 8,492,359, and 11,141,378, while also rejecting Moderna’s claim that US patent 9,504,651 was not invented by Arbutus.

Arbutus’ lawsuit, filed in 2022, alleges that Moderna’s COVID-19 vaccine technology—particularly lipid nanoparticle components crucial for stabilizing mRNA—infringes patents held by Arbutus and licensed to Genevant Sciences, with potential implications for Moderna’s royalty obligations and future mRNA products.³

Legal analysts suggest that the court’s limitations on Moderna’s defenses could strengthen Arbutus’ claims and complicate Moderna’s strategy heading into trial, particularly by narrowing the scope of issues Moderna can contest.² Although the trial has not yet begun, the partial summary judgment ruling represents a significant procedural advantage for Arbutus.

Implications for Vaccine Innovation and Legal Landscape

The 2 developments—regulatory push-pull over Moderna’s flu vaccine and the setback in patent litigation—underscore the complex landscape facing biotechnology firms at the intersection of vaccine innovation, regulatory policy, and intellectual property rights. For Moderna, success in its influenza vaccine review could solidify its role in next-generation immunization strategies. Conversely, adverse patent rulings could influence how the company navigates rights and obligations tied to foundational mRNA technologies.

As the FDA sets its deadline for a decision this summer and Moderna prepares to defend its intellectual property strategies in court, the company’s dual challenges highlight broader questions about how regulators and courts balance public health, scientific advancement, and commercial incentives in the evolving era of mRNA therapeutics.²

References

1. Neergaard L. Moderna says the FDA will consider its new flu shot after resolving a public dispute. AP News. February 18, 2026. Accessed February 18, 2026. https://apnews.com/article/moderna-flu-vaccine-mrna-fda-kennedy-

2. US FDA reverses course, will review Moderna's revised flu vaccine application. Reuters. February 18, 2026. Accessed February 18, 2026. https://www.reuters.com/business/healthcare-pharmaceuticals/us-fda-initiate-review-modernas-influenza-vaccine-2026-02-18/

3. Arbutus Biopharma Corp. Form 8-K: Current report (Date of earliest event reported: February 2, 2026). Filed February 6, 2026. Accessed February 18, 2026.

4. Yasiejko C. Moderna loses key Covid-shot patent defenses before jury trial. Bloomberg Law. February 17, 2026. Accessed February 18, 2026. https://news.bloomberglaw.com/ip-law/moderna-loses-key-covid-shot-patent-defenses-before-jury-trial