摘要
目的探索1剂次水痘疫苗高覆盖率下水痘暴发的流行因素及1剂次水痘疫苗的保护效果,为控制水痘暴发疫情、调整优化水痘免疫策略提供科学依据。方法采用1∶2配对病例对照研究,对2018年发生于江苏省苏中地区一中心小学的一起水痘暴发疫情开展流行病学调查。水痘暴发的流行因素分析采用条件Logistic逐步回归分析。结果该疫情共持续14 d,共报告水痘确诊病例45例,其中突破病例占71. 1%。突破病例的发热情况、出疹程度、病程与无免疫史病例相比均较轻(均有P <0. 05)。条件Logistic回归分析提示,参加课外辅导机构(OR=2. 6,95%CI:2. 0～3. 2),有兄弟姐妹(OR=2. 5,95%CI:2. 1～4. 3),无水痘疫苗接种史(OR=2. 7,95%CI:2. 4～4. 2),与水痘患者接触史(OR=2. 4,95%CI:1. 1～5. 3)是水痘暴发的流行因素。接种年限> 5年,初次免疫年龄<15月龄是发生突破病例的潜在危险因素(均有P <0. 05)。1剂次水痘疫苗的总体保护效果为77. 9%(95%CI:53. 3%～92. 1%)。结论突破病例临床症状较轻,1剂次水痘疫苗不足以控制水痘暴发疫情,其疫苗保护效果有限。建议采用2剂次水痘免疫策略。
Objective To explore the epidemic factors of varicella transmission under high varicella vacince coverage,assess the vaccine effectineness of one dose of varicella vaccine,so as to provide scientific basis for controlling the varicella outbreak and optimizing the varicella immunization strategy.Methods A 1∶2 paired case-control study of a varicella outbreak was conducted in a primary school in central region of Jiangsu Province in 2018. Analysis of varicella epidemic factors was performed using conditional logistic stepwise regression. Results This outbreak lasted for 14 days. A total of 45 students were infected with varicella,of which 71. 1% were breakthrough cases. The fever,rash degree and disease course of breakthrough cases were all relatively mild compared with those without immune history( all P < 0. 05). The results of conditional logistic stepwise regression suggested that participating in extracurricular tutoring institutions( OR = 2. 6,95% CI: 2. 0-3. 2),having brothers or sisters( OR = 2. 5,95%CI: 2. 1-4. 3),without vaccination history of varicella vaccine( OR = 2. 7,95% CI: 2. 4-4. 2),and contacting with varicella patients( OR = 2. 4,95% CI: 1. 1-5. 3) were risks factor for varicella transmission. Time since vaccination > 5 years and the initial immunization age < 15 months were potential risk factors for breakthrough cases. The overall vaccine effectiveness of one dose of varicella vaccine was77. 9%( 95% CI: 53. 3%-92. 1%). The fever,severity of the rash and the course of the disease were all milder than those without the history of immunization( all P < 0. 05). Conclusions The clinical symptoms of the breakthrough cases are relatively mild,and one dose of varicella vaccine is insufficient to control the outbreak of varicella with limited vaccine effectiveness. Two doses of varicella immunization strategy is recommended.
引文
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