So if everyone is infected, as the CDC director may have told Rick, perhaps the group has some sort of immunity that protects them until death.
I called the knife thing. The whole scene where Rick intructed Shane to kill the zombie through the fence was too contrived to not have been a setup.
The infection doesn't kill you. It just reanimates you once you are dead. The zombie bites kill you but they don't reanimate you. The virus does that. So you can live forever with it but when you die you will come back to life.
So basically you are right....they need to headshot everyone that dies.


