Persistence of susceptibility to measles in France despite routine immunization: A cohort analysis

Objectives. This study examined the impact of French routine programs urgin g the combined measles-mumps-rubella immunization of 15-month-old children. Methods. We applied a cohort analysis to surveillance data collected by gen eral practitioners to estimate the cumulative incidence rate per 1000 unvac cinated children and the proportion of susceptible children, by age and for each birth cohort between 1985 and 1995. Results. More than 70% of unvaccinated children born in 1985 and 1986 had m easles by the age of 10. This incidence rate dramatically decreased after i mplementation of the routine measles-mumps-rubella immunization program in 1989, but the proportion of 5-year-olds susceptible to measles has not decr eased appreciably. In 1996, more than 15% of the children born between 1990 and 1995 were susceptible. Conclusions. The measles vaccine coverage achieved by the French routine im munization program remains insufficient as regards reducing the number of s usceptible children.