STAGES OF THE ZOMBIE DISEASE:
The stages of zombie transformation are the same that occur in vampires, with two major differences: in zombies, the onset of symptoms and transformation occurs much faster and has no relation to the cycles of day and night.
Stage One: Infection. Symptoms of zombie infection appear quickly: within one or two hours, the victim will develop a headache, fever, chills and other flu-like symptoms. Zombie infections last about half as long as their vampiric counterparts, mostly between three and six hours, during which the vaccine is 100 percent effective.
Stage Two: Coma. Zombie comas are considerably more brief than vampiric comas. While physiological changes-slow pulse, shallow breathing-are similar, the coma lasts only between four and six hours. Only the very young and very old do not survive zombie comas. Zombies have been found as young as five years old and as old as 90. As with vampires, the vaccine is 50 percent effective when administered during Stage Two of the infection: the longer the victim has been in the coma, the less effective the vaccine.
Stage Three: Transformation. Zombies awaken from their comas in a catatonic state. They are unresponsive to most stimuli as they shuffle about, trying to locate their prey. Unlike vampires, there is no acclimation period; a zombie will begin hunting immediately upon transformation.
Information found here: http://www.fvza.org/zscience1.html