调查水痘暴发事件，了解水痘疫苗保护效果，为制定科学防控策略和措施提供依据。

搜索2018年9月1日至2019年1月23日，该幼儿园儿童和教职员工中出现典型的水痘样皮疹(丘疹或疱疹或结痂)者。采集8例患者的咽拭子标本开展病原学检测；利用"问卷星"和"江苏省预防接种综合服务管理信息系统"平台，收集6个班级的所有儿童的水痘疫苗接种等信息，调查疫苗的保护效果。

共搜索到水痘患者106例，儿童罹患率为14.5%(104/717)，教职工罹患率为2.8%(2/72)；首例患者为小6班儿童，2018年9月6日发病，疫情持续4个月，流行曲线显示为增殖模式，患者可分为8代。暴发波及8个班级，班级罹患率17.5%～58.5%；接种水痘疫苗者中的水痘罹患率为12.9%(8/62)，未接种水痘疫苗者中水痘罹患率为54.4%(81/149)，水痘疫苗保护率为76%(95%CI＝54%～88%)；37.5%(3/8)患者咽拭子标本水痘-带状疱疹病毒核酸阳性。

在低免疫水平人群中暴发水痘的防控难度大，水痘疫苗保护效果较好，建议进一步加强水痘疫苗接种宣传，将儿童水痘疫苗接种纳入扩大免疫规划。

To investigate the event of varicella outbreak and the protective effect of varicella vaccine to provide scientific basis for formulating prevention and control strategies.

Searches were conducted between 1 September 2018 and 23 January 2019 for typical varicella-like rashes(papules or herpes or crusts) among children and faculty members in a kindergarten; pharyngeal swab specimens from 8 cases were collected for etiological detection; using the platform of "Questionnaire Star" and "Jiangsu Provincial Comprehensive Service Management Information System for Vaccination" , information about varicella vaccination of all children in six classes were collected, and a retrospective cohort study was conducted to investigate the effect of vaccine protection.

A total of 106 cases of varicella were found, with a prevalence of 14.5% (104/717) in children and 2.8% (2/72) in faculty members; the first case was a child in Class 6, Grade 1; the case was onset on September 6, 2018, and the epidemic lasted for 4 months. The epidemic curve showed a proliferation pattern, and the cases could be divided into eight generations. The outbreak spread to 8 classes, and the incidence of the outbreak ranged from 17.5% to 58.5%; the incidence of varicella was 12.9% (8/62) in those vaccinated with varicella vaccine, 54.4% (81/149) in those not vaccinated with varicella vaccine. The vaccine protective rate was 76% (95%CI=54% to 88%). Of 37.5% (3/8) of throat swab specimens were positive for varicella-zoster virus nucleic acid.

It is difficult to prevent and control varicella outbreaks in a low immunization population. The protective effect of varicella vaccine is of significance. It is suggested to further strengthen the publicity of varicella vaccination and incorporate the vaccination of children with varicella into the expanded immunization program.