Right but when was the last time anyone you know got polio? Vaccines aren't 100% effective but if we can get the average susceptibility to the virus in the popu

Right but when was the last time anyone you know got polio? Vaccines aren't 100% effective but if we can get the average susceptibility to the virus in the population down far enough (even though it'll never be complete) there's a threshold where the virus can have a hard enough time hopping that it really makes a difference.