The short answer is yes. HEPA air purifiers capture virus particles, removing them from the air. But don't count on air purifiers to protect you from virus particles if you're cohabitating with a contagious person. When CNET spoke with Richard Shaughnessy, director of indoor air research at the University of Tulsa, in 2022, he said transmission of COVID usually happens due to close contact with an infected person. If you're sitting on a couch and chatting with someone who is infected, an air purifier across the room isn't going to remove all the harmful particles exhaled before they have a chance to reach you.