Pfizer’s Covid Antiviral Paxlovid Target of Enanta Patent Suit

Enanta Pharmaceuticals Inc. alleges that Pfizer Inc.’s Covid-19 antiviral Paxlovid infringes a patent issued last week related to ways to stop a coronavirus from reproducing, according to a federal lawsuit in Massachusetts.

Enanta seeks damages of at least a reasonable royalty “for Pfizer’s use of a coronavirus 3CL protease inhibitor claimed” in the patent, according to a complaint filed Tuesday in the US District Court for the District of Massachusetts.

“Enanta recognizes the importance of Paxlovid’s availability to patients and does not intend to seek an injunction or take other action in this litigation that would impede the production, sale ...