遵义市1起小学暴发疫情水痘突破病例的临床特征和危险因素

目的分析1起小学暴发疫情水痘突破病例的临床特征和危险因素。方法对2019年贵州省遵义市一所小学水痘暴发疫情开展流行病学调查,分析水痘突破病例的临床特征;采用病例对照设计,分析水痘突破病例的危险因素。结果在该起暴发疫情中水痘突破病例占总病例的67.5%(27/40)。水痘突破病例与无水痘疫苗(VarV)免疫史水痘病例的发热比例分别为7.4%、38.5%(χ²=5.86,P=0.015),病程>7d比例分别为25.9%、61.5%(χ²=4.78,P=0.029),皮疹>50个比例分别为40.7%、84.6%(χ²=6.83,P=0.009)。VarV初次免疫后≥5年发生水痘突破病例的风险高(OR=5.01,95%CI:1.67-15.05),VarV初次免疫年龄≥15月龄、接种2剂次VarV的风险低(OR=0.33,95%CI:0.11-0.99;OR=0.10,95%CI:0.03-0.43)。结论水痘突破病例的临床表现不典型;接种2剂次VarV预防水痘突破病例的效果好,建议将2剂次VarV纳入国家免疫规划。

Clinical characteristics and risk factors of breakthrough varicella in a primary school outbreak of Zunyi city

Objective To assess clinical characteristics and risk factors for breakthrough varicella in a primary school outbreak.Methods We conducted an epidemiological investigation of a varicella outbreak in a primary school of Zunyi city, Guizhou province in 2019 to determine clinical characteristics of breakthrough varicella cases. We used a case-control study to identify breakthrough risk factors.Results Breakthrough varicella cases accounted for 67.5%(27/40) of all varicella cases in the outbreak;7.4% of breakthrough cases and 38.5% of unvaccinated varicella cases had fever(χ2=5.86, P=0.015);25.9% of breakthrough cases and 61.5% of unvaccinated cases had clinical durations over 7 days(χ2=4.78, P=0.029);40.7% of breakthrough cases and 84.6% of unvaccinated cases had >50 skin lesions(χ2=6.83, P=0.009). The risk of breakthrough was higher among individuals who had received their initial VarV five or more years before infection(OR=5.01, 95%CI: 1.67-15.05), and was lower among individuals who had received their primary VarV at ≥15 months of age or who had received 2 doses of VarV(OR=0.33, 95%CI: 0.11-0.99;OR=0.10, 95%CI: 0.03-0.43).Conclusions Clinical manifestations of breakthrough varicella cases were atypical and milder than among unvaccinated varicella cases. Two doses of VarV was more effective against breakthrough varicella. We suggest introducing a 2-dose VarV schedule into the National Immunization Program.