IP Law Daily, PATENT—D. Del.: Most COVID-19 vaccine patent infringement claims against Moderna proceed; government-use defense narrowed, (Feb 3, 2026)

By Saurabh Kashyap, B.A., M.A., LL.B., LL.M.

The court concluded that 28 U.S.C. § 1498 applies only when the Government is the direct beneficiary of the accused use, not when vaccine doses are distributed to the public.

The federal district court in Wilmington, Delaware, has largely denied Moderna’s attempt to shift Arbutus Biopharma’s patent infringement claims to the Court of Federal Claims under 28 U.S.C. § 1498(a), holding that most accused vaccine doses were distributed for the benefit of the general public rather than the Government itself. The court ruled that only claims tied to vaccine doses administered directly to U.S. government employees fell within § 1498’s scope. At the same time, the court held that prosecution history estoppel barred Arbutus from asserting infringement under the doctrine of equivalents for its lipid nanoparticle molar-ratio patents, requiring proof of literal infringement. The court further determined that genuine disputes of material fact precluded summary judgment on indefiniteness, leaving validity issues for a jury (Arbutus Biopharma Corp. v. Moderna, Inc., No. 1:22-cv-00252-JDW (D. Del. Feb. 2, 2026)).

Background. The plaintiffs, Arbutus Biopharma Corporation and Genevant Sciences GmbH, are biotechnology companies that pioneered lipid nanoparticle (LNP) technology for delivering nucleic acids into cells. The defendants, Moderna, Inc. and ModernaTX, Inc., develop and commercialize messenger RNA (mRNA)–based therapeutics and vaccines. During the COVID-19 pandemic, Moderna partnered with the U.S. Government under Operation Warp Speed to develop and supply an mRNA-based COVID-19 vaccine, ultimately delivering more than 500 million doses under a federal supply contract.

Arbutus asserted several patents directed to LNP compositions and methods. The principal patents at issue included U.S. Patent Nos. 8,492,359 (the ’359 patent); 9,364,435 (the ’435 patent); and 11,141,378 (the ’378 patent) (collectively, the “Molar Ratio Patents”), which claim LNPs comprising nucleic acids and specific lipid components present within defined molar percentage ranges. Arbutus also asserted U.S. Patent No. 9,504,651 (the ’651 patent), which claims methods and formulations in which specified percentages of mRNA are “fully encapsulated” within lipid vesicles.

After Moderna commercialized its COVID-19 vaccine, Arbutus filed suit in February 2022, alleging direct and indirect infringement. Moderna moved to dismiss, arguing that § 1498(a) barred the claims because Moderna acted “for the Government” under a federal supply contract that included an authorization-and-consent clause. The court previously denied dismissal, and the case proceeded through claim construction and discovery.

Moderna later moved for summary judgment on three primary grounds: (1) that § 1498(a) required dismissal or transfer of the case to the Court of Federal Claims; (2) that prosecution history estoppel barred Arbutus’s doctrine-of-equivalents theories; and (3) that several asserted claims were invalid as indefinite under 35 U.S.C. § 112. The parties also filed competing motions to exclude expert testimony.

“For the Government.” The court first addressed Moderna’s § 1498(a) defense. That statute shifts liability for patent infringement to the United States when an invention is used or manufactured “by or for the United States” with the Government’s authorization and consent. Citing Astornet Technologies, Inc. v. BAE Systems, Inc., 802 F.3d 1271 (Fed. Cir. 2015), the court emphasized that § 1498 operates as an affirmative defense and that the defendant bears the burden of proving both authorization and that the accused activity was “for the Government.”

Although the Government had authorized potential infringement through the federal supply contract, the court held that authorization alone was insufficient. Relying on Larson v. United States, 26 Cl. Ct. 365 (1992), the court explained that the Government must be the direct and intended beneficiary of the accused use. Vaccines administered to members of the general public primarily benefit patients, not the Government, even if the Government pays for or facilitates distribution.

Applying that reasoning, the court held that § 1498 did not apply to the vast majority of Moderna’s vaccine doses, which were distributed to the public. However, the court reached a different conclusion for doses administered directly to federal government employees, reasoning that those doses benefited the Government by ensuring continuity of governmental operations. Claims tied to those doses, therefore, belonged in the Court of Federal Claims.

The court further held that § 1498 does not bar indirect infringement claims, citing Zoltek Corp. v. United States, 672 F.3d 1309 (Fed. Cir. 2012). Accordingly, Arbutus could pursue inducement and contributory infringement theories in the district court even with respect to government-distributed doses.

Prosecution history estoppel. Turning to infringement theories, the court held that prosecution history estoppel barred Arbutus from asserting the doctrine of equivalents for the Molar Ratio Patents. During prosecution, Arbutus amended its claims to remove the word “about” from lipid molar-percentage ranges after the examiner rejected the claims as overly broad and overlapping prior art.

Applying Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002), and subsequent Federal Circuit precedent, the court concluded that the amendments were narrowing amendments directed precisely to the numerical precision of the claimed ratios. Because Arbutus sought to recapture that surrendered territory by asserting equivalence for ratios outside the claimed ranges, amendment-based estoppel applied.

The court rejected Arbutus’s argument that the amendments were merely tangential, distinguishing cases such as Insituform Technologies, Inc. v. CAT Contracting, Inc., 385 F.3d 1360 (Fed. Cir. 2004), and Intervet Inc. v. Merial Ltd., 617 F.3d 1282 (Fed. Cir. 2010). The court emphasized that this case involved differences of degree rather than kind and that the amendments and alleged equivalents concerned the same claim limitation.

Indefiniteness and validity. Finally, the court addressed Moderna’s invalidity challenges under 35 U.S.C. § 112. Applying Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898 (2014), the court held that summary judgment was inappropriate because the parties presented competing expert testimony on how a person of ordinary skill in the art would understand the claims.

For the ’651 patent, the court found factual disputes regarding the meaning of “fully encapsulated” mRNA and the appropriate measurement methods. For the Molar Ratio Patents, the court likewise found disputes over how molar percentages should be measured and whether different methodologies yielded materially different results. Those disputes, the court held, must be resolved by a jury.

Thus, the court significantly narrowed Moderna’s reliance on § 1498(a), confined Arbutus to literal infringement theories for its molar-ratio patents, and ensured that key validity questions would be decided at trial.

The Case is No. 1:22-cv-00252-JDW.

Judge: Wolson, J.

Attorneys: John W. Shaw (Shaw Keller LLP) for Arbutus Biopharma Corp. Brian P. Egan (Morris, Nichols, Arsht & Tunnell LLP) for Moderna, Inc.

Companies: Arbutus Biopharma Corp.; Moderna, Inc.

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