Maternal and cord
measles and
rubella antibodies were compared in 15 populations from Brazil, Ecuador, Chile, India, Jordan, Nigeria, South Africa, Taiwan, and the United States. Review of the literature concerning these countries showed that a higher proportion of children 6-12 months of age responded immunologically to
measles vaccine in areas with low per capita product than in wealthier populations. The authors show that this difference reflects differences in maternal antibody titer and differences in efficiency of transport of
measles immunity across the placenta. No variation in the half-life of passive
measles immunity in the infant was found in comparing three geographic areas. When these
biologic factors are fully evaluated, it should be possible to predict the response to be expected from vaccination at any particular age without directly testing the
vaccine in children below and above generally recommended ages for vaccination. With regard to
rubella, high antibody prevalence rates were found in most of the developing countries, as well as in the United States, and these countries are therefore unlikely to encounter widespread problems with congenital
rubella. However, Taiwan, and all of four areas of Brazil have prevalence rates which are no higher than those which pertained in the United States prior to establishment of the
rubella immunization program. The authors believe that protection of the infants in these countries is a matter of high priority, but that, if approached hastily, it could exacerbate the problem.