I go to several conventions a year and come in contact with hundreds of people. It's a germaphobe's nightmare, but I wash my hands and use hand sanitizer. Still, it usually isn't enough.
Worst part is, I usually don't get sick until well after the convention is finished, and I have had ample time to infect people outside the city I was just visiting.
As far as infectious diseases are concerned, I am vector prime. I am the danger. I am the one who coughs.