Just to add another thought that I had. Is it possible that if a gnat, mosquito, fly or tick bites a walker and then bites a living person that the person can slowly get sick as the virus begins to escalate inside that person and they eventually turn?
And is it possible that a mosquito or gnat bit a walker and then somehow got into the food that the harry potter kid ate which triggered the virus to start spreading within the kid, eventually turning him?
I already love where this season is going.