I read that teachers are singularly less likely than others, including hospital staff, to get this infection, presumably because they work for years in a melting pot of infections. The teachers' immune systems are thought to be extremely well exercised, making them the equivalent of immunity-athletes.
Read where?!
I'm a teacher and bloody love my job. However I get every bug going despite 13 years in the classroom. Colds, bronchitis, sinusitis, tonsillitis, labyrinthitis stomach bugs, you name it. I've caught nits from kids loads of times. I became very ill a couple of years ago with M.E. due to contracting chicken pox as an adult and still have residual symptoms which make full time teaching a big challenge, but I persevere because I love my job and lovet class.
I'm not a superhero because I'm in contact with so many bugs. Quite the opposite - my immunity has taken a real battering over the years.