In developing countries, measles morbi-mortality represents an important public health problem, with average age at infection earlier than 12 months. Maternally antibody concentration was correlated with vaccine failure to immunize infants less than 1 year of age. Vaccine-induced immunity appears to be shorter lived than the one engendered by wild virus, suggesting that infants of vaccinated mothers may loose passively acquired antibodies faster than those of previously infected mothers. We measured the seroprevalence of measles virus antibody of 1216 children in their first year of life and of their mothers. The mean antibody concentration of mothers older than 25 years of age, from the pre-vaccination era (group 1), was bigger than of younger mothers, from vaccination era (group 2), similar to the findings in their newborn children, comparing both groups. Evaluating maternal antibody decay, we observed that children from younger mothers were susceptible to measles at a younger age than those from older mothers. However, at 6 months, around 94% children of both groups were already negatives. The immunogenicity between 6 and 12 months of age was evaluated in 552 children, at least one month after measles vaccine. The ability to produce antibodies increased from 25% for children of group 1 and 37% for children of group 2 to above 80% for both groups. Mathematical models showed that optimal age for vaccination was not influenced by maternal age. A change to an earlier age of routine vaccination is not justified by our results.
Learning Objectives: During the presentation, data from a seroprevalence study aimed to evaluate the influence of maternal measles antibodies on optimal age for vaccination will be presented. The main question to be answered is if maternal antibodies acquired from vaccination or from infection of the mother have different decay velocity in infants that could suggest modification of age for vaccination when most mothers are protected by vaccine. The best age for vaccination was estimated by mathematical models, that will also be presented
Keywords: Immunizations, Infectious Diseases
Presenting author's disclosure statement:
Organization/institution whose products or services will be discussed: None
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.