Originally Posted by Nyes the Dark
An interesting idea (not my cup of tea, but it's your group), since it plays with some variation.
My confusion is with the virus zombies. If any open wound caused by a virus zombie can cause zombism, any hit on your PCs would likely end with the others killing him/her and burning the corpse, because otherwise your screwed.
End result: The highest PC mortality rate since Hunger Games.
Unless it is a very small chance or there is some treatment?
I'd say easiest thing to do is A) Fort save, with a low enough DC that level 1 commoners will be fairly susceptible, while higher level PCs have a much lower chance of getting infected, or B) Incubation period of several days, during which time you can attempt to cure it via spells or medicine (although medicines will probably be highly experimental and my have some side effects).