re: What is the biggest movie plot hole you have ever seen?

One thing I didn't get about The Crazies.

When they go back to their house to get his police car, they find the wife and son of the dude he killed at the beginning all transformed to Crazies. The wife stabs his hand to the floor. He picks it up, and jams the blade (with his hand attached) into her neck. I would think that at this point her Crazy blood would have gotten into his blood stream to infect him, but he never turned into a Crazy in the remainder of the movie.