There are already vaccine trials underway, the 12-18 months is the minimum amount of time we allow for making sure the cure isn't worse than the disease. We're basically talking about giving this vaccine to every at-risk person in the world. If it's not safe, that would be a really bad outcome.

The unprecedented scale will allow more parallel efforts, to the point that the odds of a viable vaccine being available next year are much greater, but it won't speed up the minimum time.