2020年1月8日，深圳市確診了首例COVID-19病例，3月3日深圳市疾病預防控制中心聯合美國約翰霍普金斯公共衛生學院，在醫學預印本網站MedRxiv在線發表最新研究成果《Epidemiology and Transmission of COVID-19 in Shenzhen China: Analysis of 391 cases and 1,286 of their close contacts》，分析了深圳市391例COVID-19確診病例及1286名密切接觸者的數據，描述了COVID-19在湖北省以外傳播的一些非常關鍵的流行病學信息。
本研究通過對深圳市COVID-19早期病例及其密切接觸者進行了詳細的分析，為了解COVID-19的自然史、傳播特點和疫情防控提供科學的依據，為預測病毒的影響、評估控制措施和指導全球應對提供了證據基礎。
研究表明，COVID-19是一種潛伏期相當較短（平均4-6天），但臨床病程較長的疾病，患者需要數週時間才能康復或發生死亡。在以接觸者為基礎的監測組中，20%的人在第一次臨床評估時沒有出現任何症狀，近30%的人沒有發熱症狀，這與COVID-19相當高的無症狀攜帶率是一致的，基於接觸者監測發現的病例比通過症狀監測發現的病例或許更能準確反映SARS-CoV-2的平均感染情況。
此外，在觀察到的密切接觸者中，幼兒的感染率與人群的平均水平接近，總體來說COVID-19的傳播率相對較低，每個病例的後續傳播不到1例（0.4），這與加強監測與隔離病例相結合的措施效果密不可分。
原文鏈接：
https://www.medrxiv.org/content/10.1101/2020.03.03.20028423v1
Epidemiology and Transmission of COVID-19 in Shenzhen China: Analysis of 391 cases and 1,286 of their close contacts
Abstract
Abstract Background Rapid spread of SARS-CoV-2 in Wuhan prompted heightened surveillance in Shenzhen and elsewhere in China. The resulting data provide a rare opportunity to measure key metrics of disease course, transmission, and the impact of control. Methods The Shenzhen CDC identified 391 SARS-CoV-2 cases from January 14 to February 12, 2020 and 1286 close contacts. We compare cases identified through symptomatic surveillance and contact tracing, and estimate the time from symptom onset to confirmation, isolation, and hospitalization. We estimate metrics of disease transmission and analyze factors influencing transmission risk. Findings Cases were older than the general population (mean age 45) and balanced between males (187) and females (204). Ninety-one percent had mild or moderate clinical severity at initial assessment. Three have died, 225 have recovered (median time to recovery is 32 days). Cases were isolated on average 4.6 days after developing symptoms; contact tracing reduced this by 1.9 days. Household contacts and those travelling with a case where at higher risk of infection (ORs 6 and 7) than other close contacts. The household secondary attack rate was 15%, and children were as likely to be infected as adults. The observed reproductive number was 0.4, with a mean serial interval of 6.3 days. Interpretation Our data on cases as well as their infected and uninfected close contacts provide key insights into SARS-CoV-2 epidemiology. This work shows that heightened surveillance and isolation, particularly contact tracing, reduces the time cases are infectious in the community, thereby reducing R. Its overall impact, however, is uncertain and highly dependent on the number of asymptomatic cases. We further show that children are at similar risk of infection as the general population, though less likely to have severe symptoms; hence should be considered in analyses of transmission and control.
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