内蒙古自治区首起新冠病毒Omicron变异株BA.2感染疫情流行病学特征分析

Analysis of epidemiological characteristics of the first SARS-CoV-2 Omicron BA.2 epidemic in Inner Mongolia Autonomous Region

目的分析内蒙古自治区首起由Omicron变异株BA.2引发本土新冠病毒感染聚集性疫情的流行特征和传播过程,为急性传染病疫情防控和处置提供依据。方法将2022年4月23-5月2日内蒙古首起Omicron变异株BA.2新冠病毒感染本土疫情的感染者作为研究对象,对每例感染者进行流行病学调查、样本采集和实验室检测,重点调查临床症状、发病日期、流行病学史和感染者之间的流行病学关联。结果本次Omicron变异株BA.2疫情发生在内蒙古满洲里市,指示病例发病日期为4月22日,23日检测发现,发病到发现的时间间隔1 d。在疫情发现当天迅速采取积极措施后,后续82.61%病例均在隔离点筛查中发现,社会面清零用时7 d,疫情持续9 d,疫情未外溢到其他地区,未出现大规模社会面传播。46例病例中男女性别比1∶1.3,年龄中位数17岁,主要集中在≤18岁(50.00%)和19~59岁(36.96%)两个年龄段,职业以学生(47.83%)和家务及待业(26.09%)为主。54.34%病例有明显的首发症状,但其中80.00%病例主要为咽干、咽痒、咽痛等咽部不适症状,仅16.00%和4.00%病例有发热和乏力。学校首例所在班级罹患率为18.97%,是该校其他班级师生罹患率的38.71倍(P<0.05)。结论有效落实“四早”措施可有效阻断新冠病毒感染疫情传播扩散,为今后急性传染病防控和应急处置提供了良好的经验。

Objective To analyze the epidemiological characteristics and spreading process of the first Omicron BA.2 COVID-19 epidemic in Inner Mongolia,provide a reference for the prevention and control of acute infectious diseases in the future.Methods The infected persons during in this epidemic were taken as the research objects,epidemiological investigation,sample collection and laboratory testing were carried out for each infected person.The clinical symptoms,date of onset,epidemiological history and epidemiological association between infected persons had been investigated.Results This Omicron BA.2 COVID-19 epidemic occurred in Manzhouli of Inner Mongolia.Epidemiological investigation showed that the indicate case onset date was April 22,and detected on April 23,with only 1 day interval between onset and detection.After the rapid adoption of positive measures on the day of the first case discovery,82.61%of the cases were found by screening at the isolation point,7 days for social clearance time,9 days for the epidemic lasted,no spillover to other cities and no large-scale social transmission.In 46 cases,gender ratio was 1∶1.3,the median age was 17 years old,which was mainly concentrated in≤18 years old persons(50.00%)and 19~59 years old(36.96%).The occupation were mainly students(47.83%)and housework and unemployment(26.09%).54.34%of cases had obvious first symptoms,but 80.00%of cases mainly had pharyngeal discomfort symptoms such as pharyngeal dryness,pharyngeal itching,pharyngeal pain,only 16.00%and 4.00%of cases had fever and fatigue.The incidance rate of the class where the first case occurred in school was 18.97%,which was 38.71 times among teachers and students to other classes of this school(P<0.05).Conclusion It showed that the"four early"measures played an important role in the control of blocking the spread of COVID-19 epidemic,which provided good experience for the prevention and control of acute infectious diseases in the future.