Originally Posted by DieselDiner
One other mention - I wonder if Shane could now somehow be infected by his "scratch" - the knife he was using to cut his hand in the bus also had walker blood from the heads of the walkers he decomissioned.
I thought the same thing. Maybe the virus does not survive outside of a host.
However, in the very beginning of the show, the first people that Rick ran into when he made his way back to his house said something about people who were infected being overcome by fever, dying, then coming back. (That being what happened to the guy's wife.) If everyone was infected, wouldn't they have succombed to the fever by now?
I think that the scientist told Rick something about his wife being pregnant.