This must be hard for you to deal with, but I'll tell you this: I never saw or knew of anyone get sick when I was in highschool. People normally stay home if they feel sick unlike when you're a lot younger and can't tell when somethings up (I only ever saw one kid get sick when I was in 3rd grade). Has someone been sick before? is that why you are worried? I honestly don't think you need to fear seeing someone get sick in class.