CV and mad panic behaviour

[DJC]

If the guard was so diligent at his processes he wouldn't have gotten infected in the first place, and once he did, its reasonable he would have spread it at least somewhere else.

Not according to learned epidemiologists. 

The latest explanations are that the virus is capable of airborne transmission, hence the new measure of blocks of vacant rooms in the quarantine hotels.  There's also no reason why the guard may not have been infectious prior to his symptoms and isolation.