I'm a bit late, but I remember a few years back when I was a bit ill and I told my T I couldn't come to my session. We scheduled a phone call and he said he appreciated me telling him a lot. He said sometimes people come in sick, and then he is at risk of getting whatever they have. It doesn't matter if it's covid or something else, it's still "endangering" somebody and most people do not appreciate being sick. Plus, depending on how long it takes for the illness to take hold, you going in sick once could mean that next week your T can't work due to being sick and you will miss the session completely. I know it sucks to suddenly miss a session, but it's still better to have a zoom session than not have a session in a week at all.