most helpful answer in my clinical practice i get exposed to conjunctivitis (pink eye) several times a week. and i have never gotten it. why? handwashing and being careful not to touch my own eyes. not everyone who is exposed will contract the disease so just simple hygiene precautions should do it. if you are prescribed antibiotic drops or ointment most people are not considered to be contagious 24 hours or so after treatment.
how can i avoid giving pinkeye to a traveling companion?