Single-Dose Hepatitis A Immunization: 7.5-Year Observational Pilot Study in Nicaraguan Children to Assess Protective Effectiveness and Humoral Immune Memory Response
Single-Dose Hepatitis A Immunization: 7.5-Year Observational Pilot Study in Nicaraguan Children to Assess Protective Effectiveness and Humoral Immune Memory Response
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DOI：
10.1093/infdis/jiw411
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发表时间：
2016-11-15
影响因子：
6.4
通讯作者：
Herzog, Christian
中科院分区：
文献类型：
--
作者：
Mayorga, Orlando;Buhler, Silja;Herzog, Christian
背景。对幼儿普遍接种 2 剂甲型肝炎病毒 (HAV) 疫苗可有效控制甲型肝炎。然而，疫苗成本高昂，阻碍了流行国家的实施。为了测试单剂量疫苗接种作为一种可能的替代方案，我们在尼加拉瓜启动了一项观察性纵向研究，以评估保护效果以及通过挑战疫苗接种实现的体液免疫记忆反应。方法。经过 2003 年的血清调查，130 名最初血清阴性的儿童于 2005 年接受了一剂病毒体 HAV 疫苗，随后每年进行血清学和临床评估，直到 2012 年。7.5 年后，注射了疫苗加强剂。对出现肝炎症状的患者进行的同步抗体筛查记录了所研究社区中 HAV 的持续传播。结果。在血清调查和疫苗接种之间，25 名儿童亚临床感染了甲型肝炎（>8000 mIU/mL 抗 HAV）。其余 105 名儿童的免疫接种结果为 17-572 mIU/mL 的抗 HAV 水平。根据每年 >= 15% 的感染风险，估计有 60% 的儿童在随访期间接触过 HAV。没有儿童出现肝炎症状。 1 名儿童出现血清学突破性感染 (7106 mIU/mL)，估计保护效果为 98.3%（95% 置信区间，87.9-99.8）。加强免疫可使抗 HAV 水平平均增加 29.7 倍。结论。对于生活在高流行环境中的儿童，单剂病毒体 HAV 疫苗足以激活免疫记忆，并可提供长期保护。
Background. Universal 2-dose hepatitis A virus (HAV) vaccination of toddlers effectively controls hepatitis A. High vaccine costs, however, impede implementation in endemic countries. To test single-dose vaccination as a possible alternative, we initiated an observational, longitudinal study in Nicaragua, to assess protective effectiveness and-through challenge vaccination-humoral immune memory response.Methods. After a 2003 serosurvey, 130 originally seronegative children received one dose of virosomal HAV vaccine in 2005, followed by yearly serological and clinical assessments until 2012. After 7.5 years, a vaccine booster was administered. Concurrent antibody screening of patients presenting with hepatitis symptoms documented persistent HAV circulation in the communities studied.Results. Between serosurvey and vaccination, 25 children contracted hepatitis A subclinically (>8000 mIU/mL anti-HAV). In the remaining 105 children, immunization resulted in anti-HAV levels of 17-572 mIU/mL. Based on the >= 15% annual infection risk, an estimated 60% of children were exposed to HAV encounters during follow-up. No child presented with hepatitis symptoms. Serological breakthrough infection (7106 mIU/mL) was documented in 1 child, representing an estimated protective effectiveness of 98.3% (95% confidence interval, 87.9-99.8). Boosting elicited an average 29.7-fold increase of anti-HAV levels.Conclusions. In children living in hyperendemic settings, a single dose of virosomal HAV vaccine is sufficient to activate immune memory and may provide long-term protection.