Something I've noticed when we start to talk about/debate the ending, people inevitably bring up the vaccine. Since the surgery wasn't completed, we're left to speculate if the surgery would have been successful or not, and more importantly, if a vaccine would have helped in the first place/how much it would have helped/ what would have happened afterwards.
I thought I'd open up a topic for you all to discuss your thoughts on the topic.
I, personally, initially was more inclined to agree with the "the world is too f-ed up now, a vaccine would'nt help" camp. However, after playing through again, I came to realize that, uh, Tess and Sam and (Riley) would have TOTALLY appreciated a vaccine, guys. Imagine how differently the game would have gone if Tess and Sam had lived, as they would have if they had access to a vaccine (they both died of minor wounds that became infected.) I mean, yeah, a vaccine wouldn't be some magical panacea that would bring everything back to normal, but to be SO SURE that it wouldn't help AT ALL is a bit of a stretch (and something we can't be sure of anyway.) Just because you can't solve all problems at once doesn't mean it's not worth it, you know? A vaccine would also at least quell the infected from adding others to their ranks. Quarantine zones could be less strict without the risk of people becoming infected, they would just have to guard the place properly. What makes life suck so much in the QZ's is because even one spore getting in can wipe out the whole place, so people have very little freedom for fear of them coming back infected (that's the whole point of "quarantine".)
Overall, I think the whole "a vaccine wouldn't make a difference," argument is just trying to justify what Joel, and by extension we, did in the hospital. It's really tempting to want to feel like you "did the right thing," but the game makes it clear time and time again that Joel is no hero. I don't think the game is really asking us to feel that what Joel did was just, but to accept it.