Just to add onto the anecdote pile. I used to work for a Silicon Valley tech company which, due to it's well-known obsession with secrecy, had office buildings with a lot of closed doors you needed to grab and open to get anywhere. Probably 4-6 different doors to handle just to get to my own office (itself with a door that people grab). I've never taken more sick days in my life. I always seemed to have some sort of URT infection or stomach bug, despite trying my best to keep good hygiene.