基于广东省多个水痘疫情暴发现场的水痘疫苗保护效果研究

Effectiveness of varicella vaccine based on several varicella outbreaks in Guangdong Province

目的分析水痘疫情暴发现场中暴露人群的水痘疫苗保护效果,为水痘防控和免疫策略的调整提供依据。方法选取广东省4所发生水痘暴发疫情的学校作为现场,选择病例较为集中的班级中既往未患过水痘的学生作为研究对象,收集水痘疫苗接种情况和疫情暴发期间水痘发病情况,采用回顾性队列研究的方法分析水痘疫苗免疫史与本次罹患水痘之间的关系,评估水痘疫苗的保护效果。结果4个水痘疫情暴发现场中研究对象的水痘罹患率分别为28.3%(53/187)、32.9%(24/73)、31.9%(37/116)和36.4%(36/99),水痘疫苗接种率分别为27.3%(51/187)、78.1%(57/73)、87.1%(101/116)和49.5%(49/95)。接种1剂次水痘疫苗者罹患水痘的相对危险度(RR)分别为0.52、0.69、0.50和0.39,接种1剂次水痘疫苗的保护效果分别为48%、31%、50%和61%,总体保护效果为36%;接种2剂次水痘疫苗的保护效果均为100%。结论在水痘疫情高暴露人群中,1剂次水痘疫苗的保护效果欠佳,可考虑将水痘疫苗推荐接种剂次由1剂次调整为2剂次,以期有效地控制水痘暴发疫情的发生。

Objective To analyze the effectiveness of varicella vaccine in varicella outbreaks, so as to provide scientific basis for varicella control and the adjustment of immunization strategy. Methods Four schools in Guangdong Province which experienced varicella outbreaks were selected as study fields. Students who had not previously had varicella were selected from classes with high morbidity of varicella as study subjects. Data on inoculation history of varicella vaccine and varicella occurrence were collected from the subjects. Retrospective cohort study was used to analyze the relationship between the inoculation history of varicella vaccine and attack rates of varicella during the outbreak, and the effectiveness of varicella vac- cine was then calculated. Results Among the subjects attack rates of varicella were 28.3% （53/187） , 32.9% （24/73） , 31.9% （37/116）, and 36.4% （ 36/99）, respectively, in four schools with outbreaks of varicella. The inoculation rates of varicella vaccine were 27.3% （51/187） , 78.1% （57/73） , 87.1% （ 101/116）, and 49.5% （49/95）, respectively. Among the subjects vaccinated with 1 dose of varicella vaccine in the four schools, the relative risks developing varicella were 0.52, 0.69, 0.50, and 0.39, re- spectively; the effectiveness of varicella vaccine was 48%, 31%, 50%, and 61% for students vaccinated with 1 dose of varicella vaccine, but 100% for those vaccinated with 2 doses. Conclusion In the popula- tion with high exposure to varicella, one dose of vaccine is not enough for varicella prevention. Inoculation schedule of varicella vaccine should be adjusted from one dose to two doses among students to reduce the varicella outbreaks effectively.