Here is what both participants (for the sake of simplicity I will assume only two) need to consider:

First is how prevalent is covid19 in the locality where the session is taking place, and those the participants come from. The local positivity rate is the best measure if available. As there is currently enormous regional variations this is much more meaningful than any national level stat.

If either participant has had been diagnosed with the disease and recovered within the last 4 months then the session should be very safe for all. Same if there is a positive result to an antibody test though that raises the question of how reliable those tests are (which I am not going to go into).

Wearing a mask reduces risk esp. if it is a N95 mask worn properly.

Then there is the risk of how serious the disease will be if you do get it. While no one is completely safe it has been established that age, BMI and certain conditions like diabetes, asthma etc. make you more likely to end up in the ICU.

Bottom line is there were risks in BDSM activities before this virus came along. The risks vary with the different activities but even a foot fetish session has risk esp. if your wife finds out. This virus is another risk that needs to be factored in.