Disappearance of measles antibody in Thai infants after birth.

A seroepidemiology of measles hemagglutination inhibition antibody was studied in infants at birth to 8 months of age. It was found that at birth the antibody was greater than 1:8 in 56 of 64 newborns. At 2 and 4 months of age, 9 of 21 and 12 of 21 respectively had measles antibody titer less than 1:8, while at 8 months of age, only 1 of 6 had the antibody titer greater than 1:8. It shows that the maternal measles antibody can protect the infant at young age and the decrease in antibodies occur as the child grows. The measles vaccine should be given when the maternal passive immunity of measles disappears. This study indicates that the optimal age to recommend measles vaccination should be at the age of 9 months.