Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
Department of Public Health Information, Shenzhen, China.
Lancet Infect Dis. 2020 Aug;20(8):911-919. doi: 10.1016/S1473-3099(20)30287-5. Epub 2020 Apr 27.
Rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan, China, prompted heightened surveillance in Shenzhen, China. The resulting data provide a rare opportunity to measure key metrics of disease course, transmission, and the impact of control measures.
From Jan 14 to Feb 12, 2020, the Shenzhen Center for Disease Control and Prevention identified 391 SARS-CoV-2 cases and 1286 close contacts. We compared cases identified through symptomatic surveillance and contact tracing, and estimated the time from symptom onset to confirmation, isolation, and admission to hospital. We estimated metrics of disease transmission and analysed factors influencing transmission risk.
Cases were older than the general population (mean age 45 years) and balanced between males (n=187) and females (n=204). 356 (91%) of 391 cases had mild or moderate clinical severity at initial assessment. As of Feb 22, 2020, three cases had died and 225 had recovered (median time to recovery 21 days; 95% CI 20-22). Cases were isolated on average 4·6 days (95% CI 4·1-5·0) after developing symptoms; contact tracing reduced this by 1·9 days (95% CI 1·1-2·7). Household contacts and those travelling with a case were at higher risk of infection (odds ratio 6·27 [95% CI 1·49-26·33] for household contacts and 7·06 [1·43-34·91] for those travelling with a case) than other close contacts. The household secondary attack rate was 11·2% (95% CI 9·1-13·8), and children were as likely to be infected as adults (infection rate 7·4% in children <10 years vs population average of 6·6%). The observed reproductive number (R) was 0·4 (95% CI 0·3-0·5), with a mean serial interval of 6·3 days (95% CI 5·2-7·6).
Our data on cases as well as their infected and uninfected close contacts provide key insights into the epidemiology of SARS-CoV-2. This analysis shows that isolation and contact tracing reduce the time during which cases are infectious in the community, thereby reducing the R. The overall impact of isolation and contact tracing, however, is uncertain and highly dependent on the number of asymptomatic cases. Moreover, children are at a similar risk of infection to the general population, although less likely to have severe symptoms; hence they should be considered in analyses of transmission and control.
Emergency Response Program of Harbin Institute of Technology, Emergency Response Program of Peng Cheng Laboratory, US Centers for Disease Control and Prevention.
严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）在中国武汉迅速传播，促使中国深圳加强了监测。由此产生的数据为衡量疾病过程、传播和控制措施影响的关键指标提供了难得的机会。
从 2020 年 1 月 14 日至 2 月 12 日，深圳市疾病预防控制中心共发现 391 例 SARS-CoV-2 病例和 1286 名密切接触者。我们比较了通过症状监测和接触者追踪发现的病例，并估计了从症状出现到确诊、隔离和住院的时间。我们估计了疾病传播的指标，并分析了影响传播风险的因素。
病例的年龄大于一般人群（平均年龄 45 岁），男女比例均衡（男性 187 例，女性 204 例）。391 例病例中，356 例（91%）在初始评估时为轻度或中度临床严重程度。截至 2020 年 2 月 22 日，3 例死亡，225 例康复（中位康复时间 21 天；95%CI 20-22）。病例平均在出现症状后 4.6 天（95%CI 4.1-5.0）被隔离；接触者追踪使这一时间缩短了 1.9 天（95%CI 1.1-2.7）。家庭接触者和与病例一起旅行的接触者感染的风险更高（家庭接触者的比值比为 6.27[95%CI 1.49-26.33]，与病例一起旅行的接触者为 7.06[1.43-34.91]）。家庭二代发病率为 11.2%（95%CI 9.1-13.8），儿童感染的可能性与成年人相同（10 岁以下儿童的感染率为 7.4%，而人群平均感染率为 6.6%）。观察到的繁殖数（R）为 0.4（95%CI 0.3-0.5），平均序列间隔为 6.3 天（95%CI 5.2-7.6）。
我们关于病例及其感染和未感染的密切接触者的数据为 SARS-CoV-2 的流行病学提供了关键见解。该分析表明，隔离和接触者追踪减少了病例在社区中具有传染性的时间，从而降低了 R。然而，隔离和接触者追踪的总体影响尚不确定，且高度依赖于无症状病例的数量。此外，儿童感染的风险与一般人群相似，尽管症状不太严重；因此，在分析传播和控制时应考虑到他们。
哈尔滨工业大学应急响应计划、鹏城实验室应急响应计划、美国疾病控制与预防中心。
