[Epidemiology and prevention of measles in the United States: 30 years of vaccination].

Measles vaccine has been available and widely used in the United States for 30 years. During the first 20 years, the incidence of measles dramatically decreased and the Department of Health hoped that the disease would be eradicated from the United States by 1982. Yet, as early as 1970, some American epidemiologists started to doubt whether it would be possible to attain this goal with a single dose schedule. From 1989, many outbreaks have occurred in some inner-cities. This resurgence shows that the existence of small non-immune population groups is sufficient for a persistent and epidemic transmission of the disease. New control measures were proposed, and evaluated, to increase the vaccination coverage of these populations and to prolong the immunity of adolescents vaccinated in their early childhood. With 30 years experience, the description of the modifications of the epidemiological characteristics of measles following mass vaccination is useful for countries which became involved in such programmes more recently.