Comment by code4tee

That’s the doomsday scenario and thankfully “completely useless” is quite unlikely. However all viruses mutate and so it’s only a matter of time before the current vaccines become gradually less effective. We give people 3-4 new vaccines a year (usually in one “flu shot”) in the never ending battle against the mutating influenza virus. So it’s really important we get as many people vaccinated ASAP. Every new person infected makes millions upon millions of copies of the virus, each one being a new opportunity for mutations to develop. Stopping infections exponentially slows down the rate at which the virus can mutate simply because it’s being “photocopied” fewer and fewer times.