浙江省台州市一起COVID-19聚集性疫情的流行病学调查和分析

Epidemiological investigation and analysis of a cluster of COVID-19 in Taizhou,Zhejiang Province of China

目的对浙江省台州市一起由超级传播者扩大的2019冠状病毒肺炎(coronavirus disease 2019,COVID-19)聚集性疫情进行流行病学调查,为COVID-19疫情防控提供参考。方法采用现场流行病学方法,对COVID-19确诊病例及密切接触者进行调查;对资料进行描述性分析,采用χ^(2)检验比较密切接触者罹患率的差异。结果该起聚集性疫情流行病学关联病例共23例,其中确诊病例20例、无症状感染者3例。男性13例(56.52%),女性10例(43.48%);年龄中位数为51岁,范围30~70岁。首发病例为二代病例,发病时间为2020年1月19日,确诊时间为1月30日;一代病例为武汉返乡人员,末例病例发病时间为2月3日。疫情传播至第五代,密切接触者总罹患率为6.07%(21/346);第三代病例为超级传播者,共引起12例续发病例,其密切接触者罹患率高于其他病例密切接触者罹患率(27.27%vs.2.98%,χ^(2)=39.754,P<0.001)。结论高风险地区输入人员未及时管控、疫情初期群众和基层医师对新发传染病认识不足、诊断延误和超级传播者的出现共同导致疫情规模的迅速扩大。应提高医务人员和群众的防范意识,及时发现和管控传染源,形成新发传染病常态化防控机制。

Objective To investigate and analyze the epidemiological characteristics of a cluster of coronavirus disease 2019(COVID-19)spread by a super spreader in Taizhou,Zhejiang Province,and provide reference for prevention and control of COVID-19.Methods The field epidemiological investigation was conducted to investigate the confirmed cases and close contacts;the data were analyzed with descriptive method.Chi-squared test was used to compare the differences of attack rates among close contacts.Results A total of 23 epidemiological related cases were identified,including 20 confirmed cases and 3 asymptomatic infection cases.Thirteen(56.52%)were males,ten(43.48%)were females,and the median age was 51 years old with the range of 30 to 70 years old.The second generation case firstly developed symptoms on Jan 19th and was confirmed on Jan 30th,2020.The first generation cases were from Wuhan and the last case was confirmed on Feb 3rd,2020.The epidemic spread to the fifth generation with a total attack rate of 6.07%(21/346),among which the third generation case was a super spreader who directly transmitted to 12 subsequent cases with a significantly higher attack rate than other cases(27.27%vs.2.98%,χ2=39.754,P<0.001).Conclusion The expansion of the epidemic can be attributed to the lack of timely control of imported personnel from high risk regions,the lacking awareness of novel infectious diseases at the early stage of the epidemic and the appearance of the super spreader.To form a normalized prevention mechanism,it is necessary to improve the alertness of novel infectious diseases among medical staffs and the masses,implement prevention and control strategies in time.