But where's the fun in that?
Some of the healthiest people I've ever worked with were they guys at a local authority Refuse & Cleansing Division (I was on the bins and drains) - if you measure health by the very low number of days taken off sick with "poncey illnesses". I put this down to working outside in the fresh air, plenty of hard physical work (good general level of fitness) and a nice healthy exposure to a multitude of bacteria and viruses.
Gingernut is dead right, cram lots of over-sanitised people into a small enclosed place, it's like bug city.