RESUMEN
In order to determine whether previous measles vaccination interferes with the sero-response to yellow fever vaccine, 294 children at nine months of age were randomly assigned to immunization with yellow fever vaccine at different time intervals after measles vaccination. The seroconversion rate (SCR) and the log10 geometric mean titer (GMT) for 17 DD yellow fever vaccine at different intervals after Schwarz measles vaccination were: 1-6 days: SCR = 44/57 = 77%; GMT = 4.57; 7-13 days: SCR = 36/53 = 68%; GMT = 4.46; 14-21 days: SCR = 55/65 = 85%; GMT = 4.46; 22-27 days: SCR = 41/54 = 76%; GMT = 4.41 and >28 days: SCR = 52/65 = 80%; GMT = 4.24 (p > 0.05). We conclude that recent immunization against measles does not interfere with the sero-response to yellow fever vaccine.