Objective To investigate a varicella outbreak in a primary school in Ba'nan District of Chongqing in 2020,to understand the epidemiological characteristics of this varicella epidemic,and to formulate corresponding evidence for the prevention and control of the epidemic.Methods A field epidemiological investigation was carried out to collect case information of the varicella outbreak in the primary school in Ba'nan District of Chongqing in 2020.The incidence rate and epidemiological characteristics of varicella were analyzed by descriptive methods,and a case-control study was carried out to analyze the protective effect of varicella vaccine.Chi-square test was performed by SPSS 25.0 software,and the test level was α=0.05.Results The outbreak lasted for 96 days,involving 17classes in 5 grades,with 111 varicella cases,and the incidence rate was 13.69％(111/811).The inoculation rate of varicella vaccine was 45.95％in the case group and 61.86％in the control group.The incidence rate of varicella among vaccinated students was 0.52 times that of unvaccinated students(95％confidence interval CI:0.340-0.817),and the difference was statistically significant(x2=8.650,P=0.003).The risk of varicella of students who had received one dose of varicella vaccine was 7.97 times that of students who had received two doses of varicella vaccine(95％CI:3.190-19.070),and the difference was statistically significant(x2=25.610,P＜0.001).Conclusions To establish a chickenpox immunization barrier in schools,it is necessary to strengthen the publicity of chickenpox vaccination,especially the two-dose chickenpox vaccination,which is an effective measure to control the outbreak of chickenpox in schools.
维普
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