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目的评价北京市海淀区2007年某小学水痘暴发疫情中首发病例发现后3d内水痘疫苗应急免疫效果,为有效控制水痘暴发提供依据。方法对海淀区某小学水痘疫情相关资料及该校学生水痘疫苗既往接触及应急免疫情况进行分析,计算疫苗的有效率。结果2007年4月5日～5月10日该小学共发生水痘13例,均为学生,首例为五(6)班学生,五年级共发病11例,学生数为285人,既往患过水痘的72人、有水痘疫苗免疫史的33人、无免疫史的121人、免疫史不详的59人,易感者水痘疫苗接种率为15.5%(33/213),全部易感者水痘的罹患率为5.2% (11/213);首例发病7d后明确诊断,并于诊断后第2天完成全年级的应急免疫,应急免疫率为98.2%(167/170),应急免疫学生水痘续发率为3.6%(6/167),非应急免疫学生水痘续发率为8.9%(4/45),应急免疫有效率VE_(应急)为59.6%,95%可信区间为37.1%～88.1%。结论该小学水痘暴发疫情中,首例患者出疹后未立即隔离是导致水痘在该班级传播的主要原因;只有对易感者在首例发病后3～5d内进行水痘疫苗应急免疫,才能够迅速形成人群免疫屏障,有效控制暴发疫情。
Objective To evaluate the emergency immunization effect of varicella vaccine in the first case of outbreak of varicella in a primary school in Haidian District of Beijing in 2007 and provide basis for controlling the outbreak of varicella effectively. Methods The epidemic situation of primary school chickenpox in Haidian district and the school students’ history of the previous contact and emergency immunization of chickenpox vaccine were analyzed to calculate the efficiency of the vaccine. Results From April 5 to May 10, 2007, a total of 13 chickenpox cases were found in this primary school, all of them students. The first case consisted of five (6) students. There were 11 cases of the fifth grade with 285 students, There were 72 people with chickenpox, 33 with immunization history of varicella, 121 without immunization history, 59 with unknown immunization history, 15.5% with susceptible varicella vaccination (33/213), all those with susceptible chickenpox The attack rate was 5.2% (11/213). The first case was diagnosed after 7 days and completed the whole-year emergency immunization on the second day after diagnosis. The emergency immunization rate was 98.2% (167/170) The incidence of chickenpox was 8.9% (4/45) in non-emergency immunization students and 59.6% in emergency immunization. The 95% confidence interval was 37.1% ~ 88.1 %. Conclusions In the primary outbreak of chickenpox, the first case was not isolated immediately after rash and was the main reason for the spread of chickenpox in this class. Only when susceptible persons were immunized with varicella vaccine within 3 ~ 5 days after the first case onset were able to Rapid formation of population immune barrier, effectively control the outbreak.