The government needs to be more strict on psycidelic drugs (not sure how it's spelled correctly). But when I first saw this, I kind of thought how well it would fit together if it were a real zombie (I don't believe he was a real zombie), but it could go like this:
First zombie attacks a homeless man (predictable), is killed by the cops, and the public assumes he was either on drugs or crazy. He ate most of the homeless mans face, including his mouth, so if he dies and turned, no one would notice, because he couldn't bite, and he couldn't have a rabbid facial expression. Then one doctor could carelessly cut himself while taking the man's blood, and that's where %@#$ would get crazy. I dunno, I guess I just watch a too many zombie movies.
EDIT: The news could also use drugs or insanity to explain him not noticing being shot, and naked-ness.