成都市农村地区境外输入新型冠状病毒肺炎病例关联聚集性疫情分析

Analysis on the imported Coronavirus Disease 2019 related cluster epidemic in rural areas of Chengdu

对2020年12月成都市农村地区一起由境外输入新型冠状病毒肺炎(COVID-19)病例引发的本土聚集性疫情开展流行病学调查分析,查明感染来源和病例传播链。按照《新型冠状病毒肺炎防控方案(第七版)》要求,采用现场流行病学调查方法,结合大数据技术、视频图像调查、基因测序等方法开展新型冠状病毒(SARS-CoV-2)感染病例调查及传染源追踪溯源,分析其流行病学关联并绘制传播链。2020年12月7—17日成都市共确诊COVID-19本土病例13例,无症状感染者1例,其中12例(85.71%)有成都市郫都区太平(P区TP村)村院落的居住及活动史。P区TP村毗邻辖区指定的入境人员隔离酒店,该酒店11月8—28日入住了一批尼泊尔入境人员,且在隔离期间有5例隔离者陆续被检出SARS-CoV-2核酸阳性。通过基因测序比对,本土病例与同期尼泊尔输入病例同源,为L2.2.3分支(Pangolin分型为B.1.36),结合流行病学调查溯源线索,本土指示病例可能是由于接触隔离点生活垃圾而致感染。综上,COVID-19疫情常态化防控形势下,入境人员隔离点生活垃圾的规范管理是预防发生本土关联病例的关键环节,而基层医疗机构发热门诊哨点监测是疫情早发现关键,多部门联合流行病学调查以及基因技术的运用是现代传染病疫情调查溯源的核心环节,各地亟需加强隔离酒店管理,降低发生本土关联病例风险,同时加强农村地区公共卫生资源配置,提高农村地区疫情早期监测预警能力。

An epidemiological investigation was carried out on a local cluster of outbreak caused by imported cases of Coronavirus Disease 2019(COVID-19)in rural areas of Chengdu in December 2020,to find out the source of infection and the chain of transmission.According to Prevention and Control Protocol for COVID-19(Version 7),field epidemiological investigation was adopted,combined with big data technology,video image investigation,gene sequencing and other methods to carry out investigation into COVID-19 cases and infections source tracing,analyze the epidemiological association,and map the chain of transmission.From December 7 to 17,2020,13 local COVID-19 confirmed cases and 1 asymptomatic case were diagnosed in Chengdu,of which 12 cases(85.71%)had a history of residence and activity in the village courtyard of Taiping(TP),Pidu(P)District,Chengdu.From November 8,2020 to November 28,2020,a group of inbound people form Nepal were transferred to the designated entry personnel quarantine hotel of P District which was adjacent to the TP village.During quarantine,there were 5 cases who tested positive for COVID-19.Through gene sequencing alignment,genes of local cases and Nepalese imported cases from the same period are homologous,all belong to the lineage of L2.2.3(B.1.36 according to Pangolin lineage typing method).According to the results of field epidemiological investigation and gene sequencing analysis,the index case was most likely infected by contact with household waste of quarantine site.Under the situation of normalization prevention and control of COVID-19,sentinel monitoring of fever clinics in primary medical institutions is the key to early detection of the epidemic.The multi-department joint epidemiological investigation and the application of gene technology are the core links of the investigation and traceability of modern infectious diseases.The allocation of public health resources in rural areas needs to be strengthened.We need to improve the capacity for early surveillance and early warning of the epidemic in rural areas.