On the one hand they are exposed to far more infections, but they should also have hardier immune systems as a result.
I asked my PCP this question the other day and he said that medical workers are more aware of actions they can take to reduce the spread of infection (like washing hands often and not touching their mouths or eyes with dirty hands). I wouldn’t be surprised if there were a study out there somewhere that addresses this very question.
My mother was a nurse in the pediatric hosptial at the height of the Polio epidemic in the 50s
and I remember asking her if she was afraid of getting it
She looked at me and said “Ah, Mark we would constantly wash our hands and use proper barrier nursing. There was little risk.”
And that seems to be the case, if you wash your hands alot, and from what I read, it’s not the soap or hot/cold water but the amount of time washing that counts. You should use soap and water and rub at least 30 seconds for maximum effectiveness to remove germs
They may be aware, but do they do it? I remember a study done in a hospital using hidden cameras that found hand-washing was woefully underdone. I’ll try to find it.
Here is just one. From abstract:
Medical students, on the other hand, famously tend to acquire the symptoms of whatever disease they are currently studying.
I dunno; it seemed like every time I cycled through Microbiology lab I picked something up (and the handwashing for lab techs is pretty much non-stop). Maybe that’s what allowed all the bugs in; all the chapped skin on my hands. 
I had a lot of viral infections in my first 3 or 4 years in medicine. Since then, I tend to have a lot fewer. Perhaps it is due to hand washing, as I am fairly consistent with washing my hands between every patient, and after any significant exposures.
However I can’t rule out that I finally developed some resistance to the more common viral syndromes making the rounds.
Hmmmmm…any soapy products you experts would recommend?
I think these links are about as good as you’re going to get in terms of evidence (as opposed to anecdote). The second one will probably be of greater interest.
Occupationally Acquired Infections in Health Care Workers: Part I
Occupationally Acquired Infections in Health Care Workers: Part II