[Leftism is Mentally Deranged]

So the criminal commits a crime, then gets a disease. Now he has a new antibody. Does this method still work?
He gets a vaccination. Does this method still work?

[Izzy Dunne]

What you say is true; but this looks like it's intended for short-term use.

You have a suspect from a crime last night - you can do this quick test and see if he's still a suspect.

Chances are he didn't get a shot or a new disease in the meantime.