I'm, for some reason, fixated on prior talk about the possibility of immunity from actual turning.
The guy at the CDC said everyone was infected. We've seen some people turn without actually having been bit, so turning does not seem to be dependent on actual injury, just dying while infected. Which is everyone. Unless, as some online posts here and elsewhere posited, some are immune.
I just took it from there. Am I way off? Probably. Has it been stated clearly on the show as impossible? I didn't think so. So I'm having fun "what if-ing."