For me...
I personally just think "It's THEIR problem, I cannot get sick unless I touch them and put my fingers in my mouth, or kiss them" Or all that other stuff... If you ever DO feel sick. Your gonna have to just keep calm, take deep breathes, and keep in mind NAUSEA is a symptom of emetophobia, I don't know why our minds do it... but it does. 99% of the time, I convince myself this and find out "I'm not actually sick" and continue on with my life. I got pretty good at it. I JUST got back from a vacation at a friends a few cities away and stayed in the house where, there kid first got the flu, than the mom, than the dad. I managed to get away fine. I just watched what I put in my mouth and kept an open mind.