REVIEW ARTICLE Factors Determining Prevalence of Maternal Antibody to Measles Virus throughout Infancy: A Review

The effectiveness of vaccination against measles, the leading cause of vaccine-preventable deaths in infants globally, is greatly impacted by the level of maternal antibody to measles virus (or ªmeasles maternal antibodyº; MMA) during infancy. Variation in the prevalence of maternal antibody to measles virus between infant populations across countries and socio-demographic strata is poorly understood. We reviewed the literature on the prevalence of MMA, focusing on 3 principal determinants: starting level of maternal antibody, placental transfer of maternal antibody, and rate of decay of maternal antibody after birth. Our review identi®ed placental transfer as an important determinant, with greater ef®ciency found in studies performed in developed countries. Placental transfer was in¯uenced by gestational age, human immunode®ciency virus infection, and malaria. Antibody levels in mothers varied widely between countries, although predictably according to vaccination status within pop-ulations. Rates of antibody decay across studies were similar. Future studies should evaluate the utility of the cord blood level of MMA as a predictor of vaccine ef®cacy in infancy; inclusion of World Health Organization international reference sera will facilitate compari-sons. Greater understanding of the determinants of the prevalence of MMA will help nationa