http://apps.who.int/iris/bitstream/10665/255149/1/WER9217.pdf?ua=1

High population immunity is required to interrupt measles virus transmission due to its high infectivity. The herd protection threshold for measles is the highest of all vaccine-preventable diseases and varies in different settings, ranging from 89% to 94%.9 Mathematical modelling has estimated the herd protection threshold at 92–95% in the United States of America (USA)

Before the introduction of measles vaccine in 1963, major epidemics occurred approximately every 2 to 3 years and it is estimated that 30 million cases of measles and more than 2 million deaths occurred globally each year, and that by the age of 15 years, more than 95% of individuals had been infected with measles virus.