Paxlovid is a covalent inhibitor of the 3CLpro (Mpro) enzyme. It is in [https://www.pfizer.com/news/press-release/press-release-detail/pfizers-novel-covid-19-oral-antiviral-treatment-candidate Phase III] trials for the early treatment of SARS-CoV-2 infected patients who have not progressed to severe COVID-19 disease, and who do not immediately require hospitalisation.