It wouldn't, because the people have to die before turning. It could cure the people that are still alive, but it wouldn't reanimate the dead after curing them. But no, I'm not thinking of vaccines. Vaccines prevent infection; everybody is already infected.

Tbh a cure wouldn't help them now because even if they do get cured they will still have to avoid walkers otherwise the walkers will eat the shit out of them lol. The only way they can actually stop all of this is by getting rid of all the zombies (i.e killing them all which is almost impossible OR Waiting for all of them to rot away but people keep getting infected.) and then using a cure (implying they actually found one lol) to stop them from getting infected. So I guess you're right.