"When the rate of vaccination within a population is greater than 92%, outbreaks of measles typically no longer occur; however, they may occur again if the rate

"When the rate of vaccination within a population is greater than 92%, outbreaks of measles typically no longer occur; however, they may occur again if the rate of vaccination decreases." https://en.wikipedia.org/wiki/Measles_vaccine https://en.wikipedia.org/wiki/Measles_vaccine