[jMyles]

> What happens if the world gets into a situation where the virus mutates rapidly and we find the vaccines becoming less effective?

This is precisely the world we're in, and which we've been in since the dawn of infectious disease.

Some viruses (in fact, some entire realms of virus) exhibit this phenomenon; they're sharp as hell for things that aren't even a full-fledged organism. But we're sharper, and we make vaccines to account for subtle mutations. Often times, we get it right, which is incredible.