Live attenuated varicella vaccine in healthy 12- to 24-month-old children.
We studied live attenuated Oka/Merck varicella vaccine in 147 seronegative children 12 to 24 months of age and their 94 seronegative older siblings 2 to 12 years of age. The vaccine side effects were mild, consisting of a papular rash in 15 of 147 (10.2%) children 12 to 24 months and seven of 94 (7.4%) siblings. In a subset of 12- to 24-month-old children, modified fluorescent antibody test for membrane antigen was not detectable at seven days postimmunization but was detectable in 50% by 14 days and in 100% by 21 days. Within 6 weeks, 96.6% of children 12 to 24 months and 94.7% of siblings seroconverted. The geometric mean titer did not vary with age at immunization. One-year blood samples were obtained from 70 children 12 to 24 months of age who seroconverted; 92.9% retained detectable antibody. The geometric mean titer had decreased from 55.7 to 18.6. Of these 70 children, 34% had been exposed to varicella since immunization, and two cases of varicella were observed in seroconverters. Both cases were mild, with less than 50 vesicles. Oka/Merck varicella vaccine appears to be safe, highly immunogenic, and protective against 96% of exposures to natural varicella during the first year after vaccination in infants. Those cases of varicella that develop in immunized children appear substantially reduced in severity.
Johnson
C E
CE
Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland Metropolitan General Hospital, OH 44109.
Shurin
P A
PA
Fattlar
D
D
Rome
L P
LP
Kumar
M L
ML
D000914:Antibodies, Viral / Q000096:biosynthesis; D002644:Chickenpox / Q000517:prevention & control*; D019433:Chickenpox Vaccine; D002675:Child, Preschool; D005455:Fluorescent Antibody Technique; D014645:Herpesvirus 3, Human / Q000276:immunology*; D006801:Humans; D007223:Infant; D013997:Time Factors; D014613:Vaccines, Attenuated / Q000009:adverse effects / Q000276:immunology; D014765:Viral Vaccines / Q000009:adverse effects / Q000276:immunology
D000914:Antibodies, Viral; D019433:Chickenpox Vaccine; D014613:Vaccines, Attenuated; D014765:Viral Vaccines