目的调查一起学校水痘暴发疫情的流行病学特征,明确本起疫情发生及扩散的原因,评价水痘疫苗的保护效果。方法采用描述流行病学方法分析疫情流行病学特征,采用回顾性队列研究方法探讨疫情流行因素和水痘疫苗保护效果。结果该疫情总罹患率为5.03%(110/2 188);波及27个班4个年级,三年级和四年级罹患率较高,分别为6.48%(43/664)、5.61%(31/553);疫情历时4个月,共有7个发病高峰;在午托班午休的学生罹患率(7.01%,69/984)高于在家午休学生罹患率(4.18%,41/981),差异有统计学意义(χ~2=7.46,P=0.0063;RR=1.68,95%CI:1.16~2.44)。本次疫情中,91.82%的病例(101/110)为水痘突破病例。学生水痘疫苗总体接种率为83.09%(1 818/2 188),223名学生曾在本次疫情前罹患水痘;本次疫情发生前,水痘疫苗保护效果为75.51%(RR=0.25,95%CI:0.19~0.32),而本次疫情中,疫苗保护效果为33.50%(RR=0.67,95%CI:0.35~1.29)。结论应规范校内外午托班管理,防止疫情跨班级传播;一针次水痘疫苗在暴发疫情中保护效果较差,应进行水痘疫苗应急接种。 Objective To investigate the epidemiological characteristics of an outbreak of chickenpox in a school, clarify the causes of the occurrence and spread of the outbreak and evaluate the protective effect of the chickenpox vaccine. Methods Descriptive epidemiological methods were used to analyze the epidemiological characteristics of epidemic outbreaks. Retrospective cohort studies were conducted to investigate the epidemic factors and the protective effect of varicella vaccine. Results The total attack rate was 5.03% (110/2188); it affected four grades in 27 classes, and the rates were higher in grades three and four (6.48% (43/664), 5.61% (31/553 ). The outbreak lasted for 4 months, with a total of 7 peak incidences. The number of students who missed lunch at the lunch break (7.01%, 69/984) was higher than that of students who were at home during lunch break (4.18%, 41/981) Significance (χ ~ 2 = 7.46, P = 0.0063; RR = 1.68, 95% CI: 1.16 ~ 2.44). In this outbreak, 91.82% of the cases (101/110) were cases of chickenpox breakthrough. The overall vaccination rate of students for chickenpox was 83.09% (1 818/2 188). 223 students had chickenpox before the epidemic. The protective effect of varicella vaccine was 75.51% before the outbreak (RR = 0.25, 95% CI : 0.19 ~ 0.32). In the current epidemic, the vaccine protection effect was 33.50% (RR = 0.67, 95% CI: 0.35-1.29). Conclusions The management of afternoon care classes in schools should be standardized to prevent the spread of the epidemic across classes. The one-dose sub-chickenpox vaccine is less effective in the prevention of outbreaks and the vaccination of chickenpox vaccines should be conducted.