protease inhibitors

A Boston Globe article describes COVID-19 patients completing a course of Paxlovid – and then becoming ill again shortly thereafter. Is there something wrong with the drug? Is this something to worry about?
Pfizer's Paxlovid looks very promising in fighting COVID. It also provides a good opportunity to learn about how enzyme inhibitors work. For masochists only.
Antiviral drug development for COVID-19 took a back seat to vaccines during the brief time – when we thought that ending the pandemic was simply a matter of getting enough needles in enough arms. But the virus had other ideas: variants. Now it's looking like we may need a drug to complement the vaccines. Three are in development. Here's a look at Pfizer's PF-07321332. It should work, but don't hold me to that.