Measles-vaccine coverage (MVC) increased significantly only beginning in 1983 based on the official recommendations. The majority of women born after 1983 should have vaccine-acquired rather than naturally derived immunity. Passively transferred measles antibodies (Mab) are expected to provide protection to offsprings during their 1st few months of life.
Objective: Compare neutralizing Mab titers according to age in women aged 12-40 years, i.e., born before and after 1983.
Methods: A multicenter seroepidemiological study was conducted in France in 2005-2006; 210 outpatient or hospitalized women were enrolled and classified into 4 age groups (12-18, 19-22, 23-30, and 31-40 years). Mab titers were assessed using a reference plaque reduction neutralization assay (protection threshold > 120 mIU/ml).
Results: Ninety-four percent of subjects had a Mabs titer greater than 120 mIU/ml. Women born before 1983 had significantly higher geometric mean titers (GMTs) of Mabs than those born after 1983(1358 mIU/ml vs. 731 mIU/ml [p<0.001]). The comparison of the 4 cohorts showed a significant decrease (p<0.001) in GMTs of Mab in the female population with increasing age (670, 771, 1173, and 1821 mUI/ml, respectively, in the 12-18, 19-22, 23-30, and 31-40 years age groups). For the 1st time in France, we show in women of childbearing age that in 2005-2006 neutralizing Mab GMTs were far above protective threshold for all age groups. Women in younger age groups (with high MVC) have significantly lower Mab titers. A lower passive transfer of Mab to their offsprings could result in a shorter period of measles protection and question the measles vaccine 1st dose at 1 year.