Enanta Pharmaceuticals is suing Pfizer for patent infringement, BioSpace reports, claiming that the company now best known for its COVID vaccines used an antiviral component developed by Enanta in its Paxlovid antiviral pill.

Enanta is seeking damages for what it claims was willfull and deliberate violation of its patent via Pfizer's use of its antiviral 3CL protease inhibitor, especially EDP-235, which Entanta identified in 2021.

"Pfizer has infringed and is continuing to infringe at least one claim of the '953 patent pursuant to 35 U.S.C. § 271(b) by actively inducing the manufacture, use, sale, or offer for sale within the United States, and/or by the import into the United States, of its Paxlovid product ... Pfizer has committed and continues to commit these acts of infringement without license or authorization," the document reads.

Entanta is not seeking to have Paxlovid removed from the market or to litigate the issue, as it "recognizes the importance" of Paxlovid. However, it is seeking "treble damages," noting that, "Pfizer's infringement has damaged and will continue to damage Enanta, which is entitled to recover damages adequate to compensate for Pfizer's infringement in an amount to be determined at trial, and in any event, no less than a reasonable royalty for the use made by Pfizer of Enanta's invention."

Pfizer has yet to comment on the matter.