Vaccines usually promote immunity prior to infection very rarely do they work any other way. They all already have it and are asymptomatic until they die.
It's never been confirmed to be a virus, bacteria, fungus, prion disease, or a combination (most likely, considering that a bite causes fever and death even though they are already infected by whatever reanimated them).
I expect something that generates energy using some kind of biological cold fusion, since they don't require food to keep moving for years and don't even need to metabolize with oxygen. Some kind of sub-cellular-level bio cold fusion experiment combined with a virus/fungus and infected everyone with quantum tunneling! :awe:
Depends. One might argue this is like an infection that resides within the neural cells, like human herpesvirus 3 (varicella zoster virus, aka chickenpox; and herpes zoster, aka shingles). And, to some extent, the modern rabies vaccine, which may be a more fitting analogy in this case. I don't know if HHV-3 is actually eliminated from your body thanks to the shingles vaccine (which is just a stronger version of the varicella zoster vaccine), or if that is simply a way to bolster the immunity to prevent the latent infection from ever blossoming with symptoms once more. Whereas with rabies, you are considered infected but, as long as you are not showing symptoms, the vaccine can successfully eradicate the infection.
Which is, however, a little different, as the disease is never dormant, simply, the brand new infection hasn't incubated long enough to take hold. Herpes Zoster is always there if you ever had chickenpox, and even after getting shingles, you can still get it again - you just can't ever express a full chickenpox infection again.
Regardless, this is of course limited by the fact that a vaccine like the one for Herpes Zoster only works if your immune system is functioning. When you are dead, you are not - if a zombie virus is in neural cell and can be expressed with dead tissue, then a suppressant-style vaccine would do nothing. If it could be eradicated with a vaccine, then yea.
Also, this is fiction
Also, quantum tunneling? If I'm a zombie, can I be in your head and talk to your brother at the same time? :awe: