Loss of maternally acquired measles antibodies in well-nourished infants and response to measles vaccination, Peru.

Clinical, anthropometric, and serological evaluations were conducted at birth and at 3, 6, 9, and 10 months (post measles vaccination) in 34 well-nourished Peruvian infants. Seroconversion rate after measles vaccination was 94 percent. The rate of antibody loss was a direct function of birth titer; at age 9 months, all children had identical mean titers regardless of their titer at birth. Differences in maternally acquired measles antibodies at birth were important only during the first six months of life.