Yeah, the uncertainty of never being 100% sure we won't get X disease is scary for sure. I've heard people say here that learning how to deal with that was key in getting control over their anxiety. I haven't figured it out myself, but I do find it hopeful that other people have. No reason we won't someday be able to work it out too, if we keep at it.
I wish I had helpful advice for it, but like I said, I haven't figured it out either.