Transplacental immunity and waning of maternal antibody in measles

Since transplacental immunity and waning of maternally derived measles specific antibodies play an important role in determining the optimum age for vaccination of infants against measles, a study was carried out in which 150 paired samples and 581 infant serum samples were tested for measles specific antibodies. Out of these paired samples, 132 pairs showed measles antibodies in both mother and cord. HAI antibody was absent in 3 paired samples whereas, 5 mothers could not pass on the antibodies in the cord samples. In the remaining 10 serum samples only cord blood showed the presence of antibodies without the detectable level of antibodies in mother. Statistically no significant difference between the mother and cord blood titers was observed by applying the student 't' test for comparison of the mean (t = 0.01). Analysis of 581 infant serum samples for prevalence of maternal antibodies indicated that 83% of the samples at the age of 3 months or below had measles antibodies but with the increase in age there was tremendous loss with only 19-20% at the age of 6-7 months. After 7 months the percentage of infants which had antibody varied from 11-13%. There was negative correlation between age and seropositivity (r = -0.72) which was highly significant (p < 0.05).