I also have a fear of others getting sick along with a fear of myself getting sick. However the fear of others has generally been way worse because other people are unpredictable and I know my own body well. I'm much better now but like everything used to freak me out. Liking being around drunk people, public bathrooms, airplanes. I also was super afraid of transportation because you are so trapped.

However I think treatment for fear of others getting sick is actually a lot easier than if the fear applies to yourself. Finding a therapist who can help you is a great first step. I really recommend finding a cognitive behavioral therapist. Also exposure therapy is actually super super helpful and not nearly as scary as what you think it is. It basically starts really slowly and allows you to gradually get over your fear. It starts with words and then it works up to cartoons and then pictures of people sitting near toilets and goes like really slowly from there.

Personally, I actually did it by myself online, which is super not recommended, but for me it really worked. I also have found medication to be super helpful. I am still working through this fear, but it has gotten so so much better in the past year. Now I really can live my life without freaking out every day all the time!