I think sex workers in Switzerland may be required to undergo regular testing but I found no confirmation of that. If testing is required, a Covid test can be added to that pretty easily.
Also, the country's sex worker union is recommending safer positions: "The move comes after sex-worker advocacy group ProKoRe drafted guidelines on how to do the deed without spreading coronavirus. The group recommended that sex workers service their clients by engaging in “doggy style” and “reverse cowgirl” positions — instead of missionary style, which has a higher likelihood of transmitting the virus with closer face-to-face contact."