It’s sad that we never got to see the episode in which the Enterprise traveled back in time to a year not much later than our own(?). What we know from other time travelers: Uhura immediately recognized that large portions of the Earth’s population were speaking zombie. She then convinced Kirk to slingshot further back in time to prevent the apocalypse. No reliable reports are available as to exact details of what happened next, but we can reasonably surmise that Kirk kidnapped the small group of scientists responsible for the Apocalypse Virus, recognizing that their efforts to breed the virus were in violation of the Prime Directive. Or in violation of something anyway. Knowing Kirk as we do, we might guess that he realized that the zombie apocalypse was not the intended fate of mankind, but an unexpected aberration in the time stream, requiring that the Enterprise alter the future which, of course, required the Enterprise alter the past.
Kirk must have been quite busy for awhile. Did it work out? It’s impossible to say. We may be living in a post-Enterprise universe in which Kirk has already taken those misguided scientists away. Or we may be on the wrong side of the timeline, still waiting for the day when Uhura first hears the slurred utterances of our undead companions.
If we didn’t survive the apocalypse, though, how do we even know about the existence of Lieutenant Uhura, the woman who saved humankind?
Time travel’s tricky stuff.