Immunity to and incidence of measles in a population of Parisian children]

BACKGROUND. Measles remains prevalent in France despite the development of nationwide vaccination program. This study evaluates measles immunity and correlates it with active immunization. MATERIAL AND METHODS. A total of 250 (131 boys and 119 girls) French children, aged 2 to 15 years, seen as outpatients in our hospital, were studied from 1.01.90 to 1.06.91; 133 had received live measles vaccine during the 2nd year of life, the 117 others were not vaccine-protected. Evaluation included medical records, specially those concerning past-history of measles or measles-like diseases and immunizations. Measles IgG and IgM antibodies (ELISA) were looked for in all 250 children. RESULTS. 102 of the 117 children who were not vaccine-protected had a detectable antibody titer. 42 of these 102 had a history of measles, before the age of 5 years in 30, between 5 and 10 years in 9 and after the age of 10 years in 3. Only 4 of the 70 children aged over 10 years and not vaccine-protected had no detectable antibodies. 131 of the 133 actively immunized children had detectable antibodies. CONCLUSIONS. Measles is probably more frequently subclinical than was believed until now. Its relative frequency in France in children who had not received the live vaccine explains the high percentage of those aged over 10 years who had detectable antibodies and the relatively low incidence of the disease in teenagers and young adults.