According to Vice, the CDC's new guidelines point to casual sex being one of the first things to return to normal IF you're fully vaccinated. While they advice the best possible situation is to find another person who is also fully vaxxed as an intimate partner, it is okay for vaccinated people to be around unvaccinated people mask off. And that includes sex as well! Low risk persons are the key here. If they're low risk in small groups and you have the vaccine in its entirety (gotta stress this because I don't want people cutting corners and sending us back), "hook-up" culture is back in 2019 baby! More info--that you should definitely read--below.