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目的分析天津市津南区某中学2016年1起麻疹暴发的原因。方法对学校暴发病例开展流行病学调查,收集病例血标本和咽拭子进行实验室检测;调查全校学生含麻疹成分疫苗(Measles containing vaccine,MCV)免疫史;检测并比较津南区和无麻疹疫情的宁河区健康学生的麻疹抗体水平。结果该中学共1 530人,麻疹发病31例,其中高一年级19例、初二年级11例。26例本地病例均有≥2剂次MCV免疫史,5例外省转入学生病例免疫史不详。26例病例采集了急性期血清,其中16例麻疹IgG抗体浓度≥2 000mIU/ml,几何平均浓度(GMC)为2 819.05mIU/ml。分离到3株麻疹病毒,均为H1基因型。该校82.61%的本地学生有≥2剂次MCV免疫史。在有免疫史学生中接种后平均时间(中位数)为13.72年(5-17年)。津南区和宁河区健康学生麻疹抗体阳性率为90.96%和90.74%(x~2=0.01,P=0.94);GMC分别为488.03mIU/ml和535.49mIU/ml(t=-1.19,P=0.23)。结论继发性免疫失败(Secondary vaccination failure,SVF)是本起学校麻疹暴发的原因;SVF在麻疹病毒传播中的作用需要更多的研究。
Objective To analyze the causes of a measles outbreak in 2016 by a middle school in Jinnan District, Tianjin. Methods To carry out epidemiological investigation of school outbreaks and collect blood samples and throat swabs for laboratory testing. To investigate the immunization history of measles containing vaccine (MCV) in schools and to detect and compare the prevalence of measles containing measles Ninghe District, healthy students measles antibody levels. Results A total of 1 530 students in the secondary school, measles 31 cases, of which 19 cases of high grade, 11 cases of grade two. 26 cases of local cases were ≥ 2 doses of MCV immunization history, 5 cases of foreign students transferred to the case history of unknown. Acute sera were collected from 26 patients, including 16 measles IgG antibodies ≥ 2000 mIU / ml and geometric mean concentration (GMC) of 2 819.05 mIU / ml. Three strains of measles virus were isolated and all were H1 genotypes. 82.61% of the local school students had ≥2 doses of MCV immunization history. The average time (median) after immunization with vaccinated students was 13.72 years (5-17 years). The positive rates of measles antibody in healthy students in Jinnan District and Ninghe District were 90.96% and 90.74%, respectively (x = 2 = 0.01, P = 0.94); GMC were 488.03mIU / ml and 535.49mIU / 0.23). Conclusions Secondary vaccination failure (SVF) is the cause of measles outbreak in school. The role of SVF in the transmission of measles virus needs more study.