Before a vaccine was licensed in1963, there were an estimated 3 to 4 million cases of measles each year. In the years following 1963, the number of measles cases dropped dramatically, with only 1,497 cases in 1983, the lowest annual total reported up to that time.
From 1989 to 1991, 55,622 cases were reported with a total of 123 measles-associated deaths. Half of the cases and deaths were in young children. The most important cause of this epidemic was low immunization rates among preschool-age children. Due to increased immunization efforts after this epidemic, measles cases fell during the 1990s. Only 44 cases were reported in 2002. However, measles is still common in many other countries in the world and can easily be imported, so continued immunization against the disease is still important.