Measles is a highly contagious vaccine-preventable disease that still causes epidemics around the world. Because of the highly contagious nature of this virus, an estimated 400,000 to 500,000 cases were reported annually in the United States before the release of the vaccine in 1963.
+1,+2 At that time, it was estimated that up to 3.5 million individuals, equivalent to all the children born each year, were infected.
+1 More than 90% of U.S. citizens had been infected by the time they were 15 years old.
+3 The measles vaccine has eliminated the occurrence of epidemics in the United States and other regions of the world in which it has been widely adopted. Unfortunately, measles remains common in underdeveloped countries, and the incidence is increasing worldwide.
+3