上海市青浦区一起建筑工地新冠病毒Omicron变异株聚集性疫情流行特征分析

Epidemiological characterization of a cluster of COVID-19 caused by SARS-CoV-2 Omicron variant at a construction site in Qingpu District,Shanghai

【目的】对新冠病毒Omicron变异株引起的建筑工地聚集性疫情的流行特征进行分析,为疫情防控工作提供依据。【方法】收集上海市青浦区一建筑工地新冠病毒感染者的人口学特征、建筑工地基本情况等信息,采用描述流行病学方法进行分析,应用R软件计算基本再生系数(R0)和实时再生系数(Rt)。【结果】2022年4月12日—5月8日,该建筑工地累计报告感染者314例,罹患率60.62%;不同性别罹患率差异无统计学意义(χ^(2)=0.358,P=0.550);工人和管理人员罹患率差异有统计学意义(χ^(2)=10.868,P<0.001);接种过疫苗与未接种过疫苗者罹患率差异无统计学意义(χ^(2)=2.861,P=0.091)。感染者年龄在5个月~68岁,M(P25,P75)为49.0(39.8,54.0)岁,以男性为主(83.44%)。疫情主要集中在工人宿舍区,各宿舍区各楼栋均有感染者报告,不同楼栋罹患率在33.33%~87.50%。43%的感染者出现临床症状,以咳嗽(33.33%)、发热(30.37%)、头痛(17.04%)为主,不同性别出现临床症状的比例差异无统计学意义(χ^(2)=1.275,P=0.259)。不管是否接种过疫苗,出现临床症状的比例差异无统计学意义(χ^(2)=0.186,P=0.666)。本起建筑工地聚集性疫情R0为6.08(95%CI:4.49~8.02),Rt先下降后上升再下降。【结论】该起建筑工地聚集性疫情Omicron变异株传染性强、传播速度快、传播隐匿、症状轻,引起感染人数多,建筑工地发生疫情时须更果断采取严格的控制措施。

[Objective]To determine the epidemiological characteristics of a cluster of SARS-CoV-2 Omicron variant at a construction site and provide evidence for further COVID-19 prevention and control.[Methods]Demographic data of all COVID-19 cases at a construction site in Qingpu District,Shanghai,and basic information of the construction site were retrospectively collected through filed investigation.Descriptive epidemiology was used for the analysis.Basic reproduction number(R0)and time-dependent reproduction number(Rt)were calculated using R program.[Results]During April 12 and May 8,2022,a total of 314 cases were reported at the construction site,with an attack rate of 60.62%.The attack rate significantly differed between workers and managers(χ^(2)=10.868,P<0.001),whereas did not differ statistically by gender(χ^(2)=0.358,P=0.550)or by vaccination status(χ^(2)=2.861,P=0.091).The age of all cases ranged from 5 months of age to 68 years,with a media age of 49.0 years(interquartile range:39.8,54.0).In all cases,male was predominant(83.44%).Moreover,the epidemic was mainly concentrated in the workers’dormitory area,with infected cases identified in all buildings of each dormitory area.The attack rate ranged between 33.33%and 87.50%across the buildings.Symptoms and signs were observed among 43.0%of all cases,of which major clinical manifestations included cough(33.33%),fever(30.37%)and headache(17.04%).Clinical manifestations did not differ by gender(χ^(2)=1.275,P=0.259)or by vaccination status(χ^(2)=0.186,P=0.666).Additionally,R0 was estimated to be 6.08(95%confidence interval:4.49‒8.02).The Rt showed a decline in the beginning,followed by an increase and a re-decline.[Conclusion]The cluster epidemic of COVID-19 caused by Omicron variant at the construction site is highly contagious,spreads rapidly and quietly,causes mild symptoms,which finally resulted in a large number of infected cases.It warrants rapid and strict containment when an epidemic occurs at construction sites.