Epidemiology and specific prophylaxis of measles

In studies in the USSR, a single dose of Leningrad-16 live measles vaccine induced sero-conversion in at least 90% of vaccinees, with a mean titer of serum antibody of 1:32 and high antibody levels throughout the 15 years after vaccination. When the vaccine was correctly stored, transported, and used for mass vaccination, measles-associated morbidity decreased and the circulation of measles virus was interrupted in some towns for several years. However, childhood vaccination over a long period changed the immunologic age of the population and resulted in increased measles-associated morbidity in adults. A program for eradication of measles virus in some areas of the USSR has thus been developed. The ultimate aim of this program is the total eradication of measles. This goal can be achieved only after attainment of a high level of collective immunity (95%) through increased efficacy and quality of the vaccine. The international program of measles eradication should be based on the experiences gained through immunization programs in various countries. The key issues are (1) the elimination of measles epidemics and mortality, (2) the maintenance of a low incidence of measles over a long period, (3) the prevention of measles virus importation through epidemiologic surveillance, and (4) the maintenance of a high level of collective immunity in the total population.