Once upon a time in class, we discussed whether or not "28 days later" featured zombies. They look like zombies, they generally act like zombies, but they lack a crucial characteristic: they aren't dead. For the typical modern zombie, death is important. I mean, the rotting flesh and the decaying smell is pretty much symbolic of the living dead.
In reality, though, is the death that important? In vampire mythology, the conversion process usually focuses on the death. A person needs to be killed, buried, and suck the blood from another person before reanimating. There's a certain method to the process. With zombies, the process of conversion is more apparent while the person is still alive. They get bitten and respond with certain symptoms: fever or chills are usually the way a person goes. The response is typically very medical, at least with modern vampires. An infection takes over, the person dies, and then the zombie rises. In some narratives, however, the actual death is not highlighted. In "Spoiler," the conversion to zombie happens instantaneously while changing a diaper. There is no obvious death catalyst. In "Happy Zombie Sunrise Home," there also is no evident death in the conversion process.
"The Walking Dead" clearly has a moment of death before resurrection. Although, the conversion process is interesting here as well. Not to SPOIL anything, but Rick discovers in one of the more recent seasons that everyone is infected. As soon as a person dies, they become a zombie. A bite of a zombie, therefore, does not infect. It simply kills the person. This adds power to dying; it is the only thing that actually converts a person to zombie. In another way, however, it removes death as part of the conversion process. The person is already a "living" zombie. Death is more of a formality required for resurrection.
If death is no longer a crucial part of conversion to a zombie, this begs the question, can there be living zombies? Even in narratives where death is important, the death is rarely shown or emphasized. In "Warm Bodies," do we really know that the zombies really died before being resurrected? They aren't visibly rotting. They have all their limbs. Could it just be a medical infection...that turns their fluids into sludge and makes them eat people while they are still alive? Ok, probably not, but still...the actual dying is obviously not that important.
In the class discussion about "28 days later," someone made the comment, "they look like zombies, they're slow, they lack agency, they aren't themselves..." to which someone replied, "the same could be said about a lot of my friends when they have had too much to drink." (Obviously, i'm paraphrasing here. Also, even if your friend has a lot to drink, run if they try to bite you or eat your brains. Especially if they've been drinking this). For me, the same can be said about my friends before they have coffee. Think about it: they shamble out of bed, groaning incoherently. You say the wrong thing, and they bite your head off...just not literally. I would say many people can't make decisions for themselves before that first cup. Instead of moaning brains, they're just looking for cooooooofffffeeee....
In that case,
Your point about coffee is a valid one. It is a great metaphor for zombies, in general (hopefully this is a question on the midterm tomorrow!). I certainly love to drink my fair share of coffee and can relate to the grogginess that comes with a coffee-free day.