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.
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机译：我们在147名12至24个月血清阴性的儿童及其94名2至12岁血清阴性的兄弟姐妹中研究了Oka / Merck水痘减毒活疫苗。疫苗的副作用较轻，包括147名12至24个月儿童中的15名（10.2％）的丘疹性皮疹和94名儿童（7.4％）的7名兄弟姐妹的皮疹。在12至24个月大的儿童中，免疫后7天未检测到针对膜抗原的改良荧光抗体测试，但50％到14天和100％到21天都可以检测到。在6周内，有96.6％的12至24个月儿童和94.7％的兄弟姐妹发生了血清转化。免疫接种时的几何平均滴度不随年龄而变化。从70名12-24个月血清转化的儿童中获取一年的血液样本。 92.9％保留了可检测抗体。几何平均滴度从55.7降低到18.6。自免疫以来，在这70名儿童中，有34％接触过水痘，在血清转化者中观察到2例水痘。两种情况均为轻度，囊泡少于50个。 Oka / Merck水痘疫苗似乎是安全的，高度免疫原性的，并且可以在婴儿接种疫苗后的第一年内对96％的天然水痘疫苗提供保护。在免疫儿童中出现的水痘病例严重程度似乎大大降低。
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