Well, you never know with that show what twist it could take, Kirtman can weave a good story in the comics, which I do read but I can see where he would have someone that is immune to the infection as a new twist, or just become a little sick, and then becomes immune, he killed a walker with that machete, and it had walker blood on it, he then cuts himself deep enough where you see he can't use his hand, maybe he has to chop his hand off to save his own life.
