Contact Tracing Assessment of COVID-19 Transmission Dynamics in Taiwan and Risk at Different Exposure Periods Before and After Symptom Onset
Contact Tracing Assessment of COVID-19 Transmission Dynamics in Taiwan and Risk at Different Exposure Periods Before and After Symptom Onset
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DOI：
10.1001/jamainternmed.2020.2020
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发表时间：
2020-09-01
影响因子：
39
通讯作者：
Lin, Hsien-Ho
中科院分区：
文献类型：
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作者：
Cheng, Hao-Yuan;Jian, Shu-Wan;Lin, Hsien-Ho
2019冠状病毒病（COVID-19）对密切接触者的传播性是什么？结果100例新冠肺炎确诊病例和2761例密切接触者的病例确定研究中，总体临床二次发病率为0.7%。在症状出现后5天内开始接触指示病例的接触者发病率高于其后接触者。COVID-19在症状出现之前和之后的高传播性表明，仅发现和隔离有症状的患者可能不足以阻断传播，可能需要采取更广泛的措施，例如保持社交距离。2019冠状病毒病（COVID-19）的传播动态尚未完全了解。更好地了解传播动力学对于制定和评估有效的控制政策非常重要。目的了解新型冠状病毒感染的传播动态，评估症状出现前后不同暴露窗口期的传播风险。本前瞻性病例确定研究在台湾进行，包括实验室确诊的COVID-19病例及其接触者。研究时间为2020年1月15日至3月18日。所有密切接触者在最后一次接触指示病例后都被隔离在家14天。在隔离期间，接触者的任何相关症状（发烧、咳嗽或其他呼吸道症状）都会触发COVID-19检测。最后的后续日期是2020年4月2日。指标病例的不同暴露时间窗和不同暴露环境（如家庭、家庭和卫生保健）的继发临床发病率（仅考虑症状病例）。结果纳入100例确诊患者，中位年龄44岁（范围11-88岁），其中男性44例，女性56例。在密切接触者2761人中，有22例成对指示继发性病例。总体继发临床发作率为0.7% （95% CI, 0.4%-1.0%）。在症状出现后5天内开始接触指示病例的1818名接触者的发病率（1.0% [95% CI, 0.6%-1.6%]）高于其后接触者（852名接触者中0例，95% CI, 0%-0.4%）。299名完全有症状前暴露的接触者也有风险（发病率为0.7% [95% CI, 0.2%-2.4%]）。家庭接触者（4.6% [95% CI, 2.3%-9.3%]）和非家庭接触者（5.3% [95% CI, 2.1%-12.8%]）的发病率高于医疗保健或其他环境。发病率在40 ~ 59岁（1.1% [95% CI, 0.6% ~ 2.1%]）和60岁及以上（0.9% [95% CI, 0.3% ~ 2.6%]）人群中较高。本研究中，COVID-19在症状出现之前和之后的高传播性表明，仅发现和隔离有症状的患者可能不足以遏制疫情，可能需要采取更广泛的措施，如保持社交距离。本研究描述了2019冠状病毒病（COVID-19）的传播动态，并评估了症状出现前后不同暴露窗口期的传播风险。
Question What is the transmissibility of coronavirus disease 2019 (COVID-19) to close contacts? Findings In this case-ascertained study of 100 cases of confirmed COVID-19 and 2761 close contacts, the overall secondary clinical attack rate was 0.7%. The attack rate was higher among contacts whose exposure to the index case started within 5 days of symptom onset than those who were exposed later. Meaning High transmissibility of COVID-19 before and immediately after symptom onset suggests that finding and isolating symptomatic patients alone may not suffice to interrupt transmission, and that more generalized measures might be required, such as social distancing.Importance The dynamics of coronavirus disease 2019 (COVID-19) transmissibility are yet to be fully understood. Better understanding of the transmission dynamics is important for the development and evaluation of effective control policies. Objective To delineate the transmission dynamics of COVID-19 and evaluate the transmission risk at different exposure window periods before and after symptom onset. Design, Setting, and Participants This prospective case-ascertained study in Taiwan included laboratory-confirmed cases of COVID-19 and their contacts. The study period was from January 15 to March 18, 2020. All close contacts were quarantined at home for 14 days after their last exposure to the index case. During the quarantine period, any relevant symptoms (fever, cough, or other respiratory symptoms) of contacts triggered a COVID-19 test. The final follow-up date was April 2, 2020. Main Outcomes and Measures Secondary clinical attack rate (considering symptomatic cases only) for different exposure time windows of the index cases and for different exposure settings (such as household, family, and health care). Results We enrolled 100 confirmed patients, with a median age of 44 years (range, 11-88 years), including 44 men and 56 women. Among their 2761 close contacts, there were 22 paired index-secondary cases. The overall secondary clinical attack rate was 0.7% (95% CI, 0.4%-1.0%). The attack rate was higher among the 1818 contacts whose exposure to index cases started within 5 days of symptom onset (1.0% [95% CI, 0.6%-1.6%]) compared with those who were exposed later (0 cases from 852 contacts; 95% CI, 0%-0.4%). The 299 contacts with exclusive presymptomatic exposures were also at risk (attack rate, 0.7% [95% CI, 0.2%-2.4%]). The attack rate was higher among household (4.6% [95% CI, 2.3%-9.3%]) and nonhousehold (5.3% [95% CI, 2.1%-12.8%]) family contacts than that in health care or other settings. The attack rates were higher among those aged 40 to 59 years (1.1% [95% CI, 0.6%-2.1%]) and those aged 60 years and older (0.9% [95% CI, 0.3%-2.6%]). Conclusions and Relevance In this study, high transmissibility of COVID-19 before and immediately after symptom onset suggests that finding and isolating symptomatic patients alone may not suffice to contain the epidemic, and more generalized measures may be required, such as social distancing.This study delineates the transmission dynamics of coronavirus disease 2019 (COVID-19) and evaluates the transmission risk at different exposure window periods before and after symptom onset.