mostly bs....disease needs opportunity and a host.....why should teachers be any more fearful of disease than the rest of us.....nurses don't get sick from their patients who are coughing, gagging, spitting up, vomiting, pooping, peeing etc or at least they don't get sick very oftern....
use good handwashing techniques, get enough sleep, fish oil, vitamin c, and d, and drink plenty of fluids...