2022年一起由新型冠状病毒Delta变异株引起365例感染者的暴发疫情特征

Characteristics of 365 infected cases for COVID-19 outbreak caused by SARS-CoV-2 Delta variant in 2022

目的 分析2022年1月河南省禹州市新型冠状病毒肺炎(新冠肺炎)暴发疫情的流行病学特征,为完善新冠肺炎防控措施提供科学依据。方法 收集2022年1月禹州市新冠肺炎暴发疫情相关信息,进行描述性分析。结果 以病例报告日期统计,禹州市此次疫情持续18 d(1月2日至19日),共报告365例新型冠状病毒感染者,其中危重型3例(0.8%),重型12例(3.3%),无死亡病例。感染者年龄1月龄至98岁,平均为(43.6±23.1)岁,男女比例1∶1.3,农民占51.5%(188例)。潜伏期为1.0~9.0 d,M(P_(25),P_(75))为5.5(4.3,7.0)d。病例呈现明显的家庭聚集性,共发生70起家庭聚集性疫情,家庭续发率为29.9%。引起疫情的毒株为Delta变异株(B.1.617.2进化分支),基本再生系数(R_(0))为5.5(95%CI为3.0~9.3),随着控制措施的实施,动态再生系数(R_(t))呈下降趋势。结论 此次禹州市疫情具有明显的家庭聚集性,通过多种“疫情放大器”,导致大规模疫情的出现。应全面加快疫情防控速度,重点关注“疫情放大器”场所。

Objective To analyze the epidemiological characteristics of COVID-19 outbreak in Yuzhou city,Henan province in January 2022,and provide evidence for the improvement of COVID-19 prevention and control.Methods The information about local COVID-19 outbreak in Yuzhou city,Henan province from January 2 to January 19,2022 was collected for descriptive analysis.Results The outbreak lasted 18 d (from Jan 2 to 19) based on the reported date,and a total of 365 confirmed cases were reported in Yuzhou city.There were 12 severe cases (3.3%) and 3 critical cases (0.8%);no deaths were reported.The age of the cases ranged from 1 months to 98 years,with a mean of (43.6±23.1) years.Of all cases,the ratio of male to female was 1:1.3,and51.5%were farmers.The incubation period was 1.0-9.0 d,with a median of 5.5 (4.3,7.0) d.The cases showed obvious characteristics of household cluster.A total of 70 household cluster occurred,with the household secondary attack rate of 29.9%.The outbreak was caused by Delta variant (B.1.617.2),and the basic reproduction number (R_(0)) was 5.5 (95%CI:3.0-9.3),which showed a trend of gradual decline with the implementation of control measures.Conclusions The outbreak in Yuzhou city showed obvious characteristics of household cluster,and through a variety of epidemic amplifier,it led to the emergence of large-scale epidemic.Therefore,the speed of epidemic prevention and control should be comprehensively accelerated,and the epidemic amplifier sites should be focused on.