Over five-year follow-up of Oka/Merck varicella vaccine recipients in 465 infants and adolescents.

A total of 465 healthy infants and adolescents ages 12 months to 17 years without a known history of varicella or recent exposure to varicella-zoster virus VZV were immunized with live attenuated Oka/Merck varicella vaccine from November, 1984, through April, 1989. The vaccine administered was from 1 of 7 production lots containing from 950 to 3265 plaque-forming units and was well-tolerated with few side effects. The seroconversion rate for seronegative subjects was 94.6% (403 of 426). This varied by lot from 85% (950 plaque-forming units) to 100% (3010 and 3265 plaque-forming units). Breakthrough disease after exposure to varicella in seroconverters during 5 to 10 years of follow-up was 18.6% (75 of 403). The breakthrough disease was characterized by a maculopapular rash with a median of 35 lesions, most of which were macules. Breakthrough disease lasted a median of 5 days and the median temperature was 99 degrees F; 65.3% (49 of 75) of subjects were afebrile and 2.7% (2 of 75) of subjects had temperatures of > 102.9 degrees F. Varicella vaccine provides excellent (94.6%) seroconversion, and most children who developed breakthrough disease (18.6%) experienced a modified, milder form of illness than has been observed with natural varicella in unvaccinated subjects.

Duke Scholars

Author Dennis Alfred Clements III Pediatrics, General Pediatrics and Adolescent Health

Author Emmanuel Benjamin Walter Jr. Pediatrics, General Pediatrics and Adolescent Health