Factors determining prevalence of maternal antibody to measles virus through infancy: A review

The effectiveness of vaccination against measles, the leading cause of vacc ine-preventable deaths in infants globally, is greatly impacted by the leve l of maternal antibody to measles virus (or "measles maternal antibody"; MM A) during infancy. Variation in the prevalence of maternal antibody to meas les virus between infant populations across countries and sociodemographic strata is poorly understood. We reviewed the literature on the prevalence o f MMA, focusing on 3 principal determinants: starting level of maternal ant ibody placental transfer of maternal antibody, and rate of decay of materna l antibody after birth. Our review identified placental transfer as an impo rtant determinant, with greater efficiency found in studies performed in de veloped countries. Placental transfer was influenced by gestational age, hu man immunodeficiency virus infection, and malaria. Antibody levels in mothe rs varied widely between countries, although predictably according to vacci nation status within populations. Rates of antibody decay across studies we re similar. Future studies should evaluate the utility of the cord blood le vel of MILIA as a predictor of vaccine efficacy in infancy; inclusion of Wo rld Health Organization international reference sera will facilitate compar isons. Greater understanding of the determinants of the prevalence of MMA w ill help national policy makers determines the appropriate age for measles vaccination.