Because you pick up immunity to various things in small doses. Someone yesterday called them mini-inoculations. This is a point I can never quite make successfully with my germaphobe friends. They say things like “We LIKE hand sanitizer!”
It’s a basic principle, but with biowarfare the rules might be a tad different. Smaller amounts of contaminant may have enough punch to get through, by design.
No, the reverse. The spokesperson said the sick person shouldn’t be in crowds for too long.