Willkie secured the dismissal of a high-profile, contentious patent-infringement case involving the COVID-19 vaccine brought by Alnylam Pharmaceuticals against Pfizer in the District of Delaware after over three years of litigation.

On July 30, Chief Judge Colm Connolly dismissed Alnylam’s patent-infringement suit against Pfizer and co-defendant BioNTech, issuing a non-infringement judgment in favor of the defendants. After over three years of litigation, Pfizer and BioNTech prevailed on their non-infringement theory under Alnylam’s own claim construction. Willkie represented Pfizer and Winston & Strawn represented BioNTech in three patent-infringement cases brought by Alnylam Pharmaceuticals alleging that Pfizer and co-defendant BioNTech’s Comirnaty® product infringed Alnylam patents related to lipid nanoparticle (LNP) technology.

The Pfizer/BioNTech vaccine employs specific LNPs to help deliver the vaccine’s mRNA in the vaccine, which is the genetic material the COVID-19 vaccines use to produce an immune response. Alnylam alleged infringement and sought an undisclosed amount of damages based on vaccine sales since Alnylam’s patents issued. Pfizer and BioNTech maintained that the patents were not infringed, invalid, and were unenforceable.

On April 28, 2025, Chief Judge Connolly denied Alnylam’s motion to further interpret certain claim language in the patents asserted against Pfizer and BioNTech. The judge noted that Alnylam’s objections to the Court’s 2023 interpretation were “troubling,” given that the definition adopted by the Court was the one Alnylam itself had proposed.

Following that April 28 order, Alnylam withdrew its opposition to BioNTech and Pfizer’s motion for summary judgment on non-infringement and asked Chief Judge Connolly to enter judgment of non-infringement in defendants’ favor. The judge canceled the jury trial scheduled for July 7, 2025—which would have been the first of many patent cases concerning the COVID-19 vaccines to reach a jury—and stayed the case.  In a recent U.S. Securities and Exchange Commission filing, Alnylam said that the judge's interpretation of the patent claims potentially placed the Pfizer and BioNTech vaccine outside the coverage of Alnylam's patents.

The Willkie team was led by partner Sara Tonnies Horton and included partner Matthew Freimuth and associate Dan Constantinescu, with assistance from associates Keaton Sheeler, Amanda Maxfield and Alison Robins.