Objective: To explore clustered epidemic of COVID-19 in Liaocheng city and analyze infection status and chain of transmission of the cases. Methods: A joint investigation team of emergency response for COVID-19 epidemic by CDC professional workers of Liaocheng city and district at two levels on January 30, 2020. According to a indicator case from ZH supermarkets, close contacts and related subjects were tracked and screened on February 1, including ZH supermarket employees, family members having contact history with related cases during January 13-26, supermarket clients during January 16-30 and family members of related cases. an epidemiological investigation was carried on and their swab of nose/throat were collected and were sent to Liaocheng CDC laboratory, real-time fluorescence quantitative RT-PCR was used to detect nucleic acids of SARS-CoV-2. Results: a total of 8 437 people were screened during January 30 to February 9, 2020 (120 employees of supermarket, 93 family members, and 8224 clients of supermarket). The epidemic was caused by ZH cases and brought clustered cases in four families. A total 25 cases of SARS-CoV-2 infection, the total infection rate of subjects was 0.30% (25/8 437) with 22 confirmed cases (0.26%, 22/8 437) and 3 asymptomatic patients (0.04%, 3/8 437), asymptomatic patients accounted for 12.00% (3/25) of all infection cases. The infection rates of supermarket employees, family members of confirmed cases and supermarket clients were 9.17% (11/120), 12.90% (12/93) and 0.02% (2/8 224). Conclusions: This was a cluster epidemic caused by one imported case of COVID-19 in a supermarket of Liaocheng city. Prevention and control of cluster epidemic should be focused on chain of community transmission and family cluster cases. It must also be an attention for transmission risk of asymptomatic patients.
目的： 调查一起聊城市新型冠状病毒肺炎（COVID-19）聚集性疫情，分析其病例感染情况及疫情传播链。 方法： 2020年1月30日聊城市、区两级CDC专业人员组成疫情处置联合调查组，针对来源于ZH超市COVID-19指示病例，2月1日开展密切接触者及相关对象追踪和筛查，包括ZH超市员工、与相关病例1月13-26日有接触史的家庭成员、1月16-30日超市顾客及其相关病例家属，完成流行病学个案调查，并采集其鼻/咽拭子标本送到聊城市CDC实验室，采用实时荧光定量RT-PCR法进行新型冠状病毒核酸检测。 结果： 2020年1月30日至2月9日，共筛查调查对象8 437人（超市员工120人、病例家属93人、超市顾客8 224人），该疫情是ZH超市造成的传播链并引起4起家庭聚集性病例，新型冠状病毒感染病例25例，调查对象总的感染率为0.30%（25/8 437），其中，确诊病例22例（0.26%，22/8 437），无症状感染者3例（0.04%，3/8 437），无症状感染者占全部感染病例的12.00%（3/25）；超市员工、病例家属和超市顾客的感染率分别为9.17%（11/120）、12.90%（12/93）和0.02%（2/8 224）。 结论： 这是一起聊城市某超市输入性病例引起COVID-19聚集性疫情，提示聚集性疫情防控工作重点在于社区传播链和家庭聚集性病例，还需关注无症状感染者的传播风险。.
Keywords: Asymptomatic patient; COVID-19; Cluster epidemic; Community transmission; Imported case.