Measles Vaccine - Effectiveness

Effectiveness

Before the widespread use of a vaccine against measles, its incidence was so high that infection with measles was felt to be "as inevitable as death and taxes." Today, the incidence of measles has fallen to less than 1% of people under the age of 30 in countries with routine childhood vaccination. In the United States, reported cases of measles fell from hundreds of thousands to tens of thousands per year following introduction of the vaccine in 1963 (see chart at right). Increasing uptake of the vaccine following outbreaks in 1971 and 1977 brought this down to thousands of cases per year in the 1980s. An outbreak of almost 30,000 cases in 1990 led to a renewed push for vaccination and the addition of a second vaccine to the recommended schedule. Fewer than 200 cases have been reported each year since 1997, and the disease is no longer considered endemic in the United States.

The benefit of measles vaccination in preventing illness, disability, and death has been well documented. The first 20 years of licensed measles vaccination in the U.S. prevented an estimated 52 million cases of the disease, 17,400 cases of mental retardation, and 5,200 deaths. During 1999–2004, a strategy led by the World Health Organization and UNICEF led to improvements in measles vaccination coverage that averted an estimated 1.4 million measles deaths worldwide. The vaccine for measles has led to the near-complete elimination of the disease in the United States and other developed countries. It was introduced in 1963. These impressive reductions in death and long-range after-effectiveness were initially achieved with a live virus version of the vaccine that itself caused side effects, although these are far fewer and less serious than the sickness and death caused by measles itself. While preventing many deaths and serious illnesses, the live virus version of the vaccine did cause side effects in a small percentage of recipients, ranging from rashes to, rarely, convulsions.

Measles is endemic worldwide. Although it was declared eliminated from the U.S. in 2000, high rates of vaccination and good communication with persons who refuse vaccination are needed to prevent outbreaks and sustain the elimination of measles in the U.S. Of the 66 cases of measles reported in the U.S. in 2005, slightly over half were attributable to one unvaccinated individual who acquired measles during a visit to Romania. This individual returned to a community with many unvaccinated children. The resulting outbreak infected 34 people, mostly children and virtually all unvaccinated; 9% were hospitalized, and the cost of containing the outbreak was estimated at $167,685. A major epidemic was averted due to high rates of vaccination in the surrounding communities.