Deng Z Q, Xia W, Fan Y B, Wang R, Tu Z Z, Wang W K, Wu J W, Yang S, Chen H Y
Nanchang Municipal Center for Disease Control and Prevention, Collaboration Unit for Field Epidemiology of State Key Laboratory for Infectious Disease Prevention and Control, Jiangxi Provincial Key Laboratory of Animal-origin and Vector-borne Diseases, Nanchang 330038, China.
Nanchang Xihu District Center for Disease Control and Prevention, Nanchang 330025, China.
Zhonghua Liu Xing Bing Xue Za Zhi. 2020 Sep 10;41(9):1420-1423. doi: 10.3760/cma.j.cn112338-20200313-00334.
Based on an investigation of an outbreak of COVID-19 in Nanchang, to understand the transmission process, analyze the infectivity of the cases in incubation period and asymptomatic carrier, and evaluate the transmission risks in different exposures. Case investigation was based on the traditional epidemiological survey, combined with analysis based on big data about population movement trajectories. Transmission chain was identified to indicate transmission relationship. A total of 27 cases were found in this cluster epidemic, including 25 confirmed cases, 1 suspected case (index case) and 1 asymptomatic carrier. A total of 347 close contacts were found. The secondary attack rate was 7.2% (25/347). The infection rates in close contacts of the first, second, third and fourth generation cases were 52.6% (10/19), 6.1% (13/213), 2.3% (2/88) and 0.0% (0/27), respectively. Asymptomatic carrier caused household transmission. The infection rates in close contacts after having meals, sharing rooms/beds, having work contacts, having neighbor contacts, having same time medical services or sharing wards and sharing vehicles with the patients were 10.6%(17/160), 10.0%(20/201), 5.3%(5/94), 0.0%(0/30), 0.0%(0/18) and 0.0%(0/17), respectively. The infection source of this cluster epidemic was a suspected case from Wuhan. Analysis based on big data about population movement trajectories can help to search the cases and close contacts accurately. The proposed epidemic prevention and control measures based on this investigation were effective.
基于对南昌市新冠肺炎疫情的调查，以了解传播过程，分析潜伏期病例和无症状感染者的传染性，并评估不同暴露情况下的传播风险。病例调查基于传统的流行病学调查，并结合基于人口流动轨迹大数据的分析。确定传播链以表明传播关系。本次聚集性疫情共发现27例病例，其中确诊病例25例、疑似病例（首例病例）1例、无症状感染者1例。共发现347名密切接触者。二代发病率为7.2%（25/347）。第一代、第二代、第三代和第四代病例的密切接触者感染率分别为52.6%（10/19）、6.1%（13/213）、2.3%（2/88）和0.0%（0/27）。无症状感染者造成了家庭传播。与患者共进餐、同住/同床、工作接触、邻居接触、同时就医或同病房以及同乘车辆后的密切接触者感染率分别为10.6%（17/160）、10.0%（20/201）、5.3%（5/94）、0.0%（0/30）、0.0%（0/18）和0.0%（0/17）。本次聚集性疫情的感染源为一名来自武汉的疑似病例。基于人口流动轨迹大数据的分析有助于准确查找病例和密切接触者。基于本次调查提出的疫情防控措施是有效的。
