[An investigation on serum antibody level of varicella-zoster virus in healthy population in Beijing].

Objective: To assess the level and trend of varicella-zoster virus (VZV) antibody among healthy population in Beijing in 2017, after the five-year implementation of the two doses varicella vaccination strategy in 2012, and to provide evidence for scientific evaluation of immunization strategy. Methods: A total of 2 144 subjects in ten age groups from 8 districts of Beijing city were recruited in this study using cross-sectional survey based on multi-stage cluster random sampling method. Serum samples were collected and VZV antibody was detected by ELISA. The influencing factors of antibody concentration and positive rate were analyzed and compared with the study in 2012. The antibody concentration and antibody positive rate were analyzed by nonparametric test and χ² test respectively. Results: The ratio of subjects with registered residence in Beijing city to other provinces was 1∶1. The ratio of male to female was 1∶1.08. The median concentration of VZV antibody was 341.4 (78.6, 1 497.8) mIU/ml, and the total antibody positive rate was 71.1% (1 524/2 144). There were significant differences in antibody positive rate (χ²=736.39, P<0.01) and antibody concentration (χ²=740.34, P<0.01) among different age groups. The antibody positive rate generally increased with age (χ²trend=7.32, Ptrend<0.01). Among 862 children under 14 years old, the antibody positive rate of two doses vaccination 72.8% (182/250) was significantly higher than that of one dose vaccination 51.9% (154/297) (χ²=25.14, P<0.01). There was significant difference between 1-4 years old group (χ²=11.71, P<0.01) and 10-14 years old group (χ²=5.95, P=0.02), but not in 5-9 years old group (χ²=3.00, P=0.07). Compared with the study in 2012, the antibody positive rate increased in 5-9 years old group (χ²=14.35, P<0.01) and decreased in 1-4 years old group (χ²=11.51, P=0.01) in 2017. Conclusion: The recommended varicella booster vaccination has significantly improved the VZV antibody level of children in Beijing city. In the future, it is necessary to explore a more optimized two doses varicella vaccination schedule for children in combination with epidemiological evidence.目的： 了解北京市2012年实施2剂次水痘疫苗免疫策略5年后的2017年健康人群水痘-带状疱疹病毒（VZV）抗体水平及变化趋势，为科学评价免疫策略提供依据。 方法： 采用横断面调查和多阶段整群随机抽样方法，在北京市8个区，分10个年龄段，共招募2 144名受试者，采集受试者血清标本，使用酶联免疫吸附试验检测VZV抗体，分析抗体浓度和阳性率的影响因素，并与2012年结果进行对比。主要采用非参数检验和χ²检验对抗体浓度和抗体阳性率进行比较。 结果： 受试者本市与外省户籍比例为1∶1，男女比例为1∶1.08。VZV抗体浓度M（Q1，Q3）为341.4（78.6，1 497.8）mIU/ml，总抗体阳性率为71.1%（1 524/2 144）。不同年龄组抗体阳性率（χ²=736.39，P<0.01）和抗体浓度（χ²=740.34，P<0.01）均有差异。抗体阳性率随年龄增加而升高（χ2趋势=7.32，P趋势<0.01）。≤14岁的862名儿童中，2剂次受试者抗体阳性率为72.8%（182/250）高于1剂次的51.9%（154/297）（χ²=25.14，P<0.01），其中1~4岁组（χ²=11.71，P<0.01）、10~14岁组（χ²=5.95，P=0.02）差异有统计学意义，5~9岁组略高但差异无统计学意义（χ²=3.00，P=0.07）。与2012年相比，2017年5~9岁组抗体阳性率上升（χ²=14.35，P<0.01），但1~4岁组抗体阳性率下降（χ²=11.51，P=0.01）。 结论： 北京市推荐水痘疫苗加强免疫显著提高了儿童VZV抗体水平，未来需要结合流行病学证据探索更为优化的儿童2剂次水痘疫苗接种程序。.