SARS-CoV-2污染的进口冷链产品导致的一起大连本土新冠疫情

A Local COVID-19 Outbreak in Dalian Caused by Imported Cold-chain Products Contaminated by SARS-CoV-2

2020年12月15日,大连市报告了4名码头冷链货物搬运工人SARS-CoV-2核酸检测呈阳性,在此之前,大连市已经连续136天没有报告本土病例。在这次大连COVID-19疫情(简称"大连新冠疫情")中,我们收集了2020年12月15日至2021年1月8日期间大连新冠疫情中全部感染者(83)及部分接触的轮船货物样本,其中确诊病例占61.45%(51/83),无症状感染者占38.55%(32/83)。通过高通量测序,共获得76条SARS-CoV-2全基因组序列,其中72条(86.75%,72/83)来自临床样本,4条来自R国籍A货船上的冷链食品外包装样本。基因组分析数据显示,与武汉参考株(NC;45512)相比,76条全基因组分别存在12~16个核苷酸突变位点,共享12个核苷酸突变位点,符合B.1.1进化分支突变特征。结合病毒基因组学和现场流行病学调查结果综合分析表明,大连新冠疫情是一起由SARS-CoV-2污染的进口冷链产品感染码头工人导致的本土疫情,在传播过程中至少形成了3个病毒代际和3个相对独立的传播链。

On December 15,2020,four dock workers tested positive for severe acute respiratory syndrome -coronavirus 2(SARS -CoV -2)nucleic acids and were reported by Dalian. Up until then,Dalian City had not reported local cases for 136 consecutive days. In this coronavirus disease 2019(COVID-19)outbreak(referred to as the"Dalian COVID-19 outbreak"),samples from all infected persons(83)and part from the ship cargoes in contact with them during December 15,2020 to January 8,2021 were collected. Confirmed cases accounted for 61.45%(51/83)and asymptomatic infections accounted for 38.55%(32/83). Through high - throughput sequencing,76 SARS - CoV - 2 whole - genome sequences were obtained,of which 72(86.75%)were from clinical samples,and 4 from cold-chain food packaging surface samples on cargo ship A of country R. Refer to Wuhan reference strain(NC;45512),genome analysis revealed 12 - 16 nucleotide mutations in 76 whole genomes sharing 12 nucleotide mutations and belong to the SARS-CoV-2 branch of B.1.1. Viral genomics and field epidemiological investigations showed that the Dalian COVID-19 outbreak was a local epidemic caused by dock workers infected with imported cold - chain products contaminated with SARS - CoV - 2. During transmission,≥3 virus generations and three relatively independent transmission chains were formed.