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Epidemiological parameters of COVID-19 and its implication for infectivity among patients in China, 1 January to 11 February 2020
- Qing-Bin Lu1,2 , Yong Zhang2,3 , Ming-Jin Liu4 , Hai-Yang Zhang5 , Neda Jalali4 , An-Ran Zhang4,5 , Jia-Chen Li5 , Han Zhao3 , Qian-Qian Song3 , Tian-Shuo Zhao1 , Jing Zhao5 , Han-Yu Liu1 , Juan Du1 , Ai-Ying Teng5 , Zi-Wei Zhou5 , Shi-Xia Zhou5 , Tian-Le Che5 , Tao Wang5 , Tong Yang5 , Xiu-Gang Guan5 , Xue-Fang Peng5 , Yu-Na Wang5 , Yuan-Yuan Zhang5 , Shou-Ming Lv5 , Bao-Cheng Liu5 , Wen-Qiang Shi5 , Xiao-Ai Zhang5 , Xiao-Gang Duan6,7 , Wei Liu5,7 , Yang Yang4,7 , Li-Qun Fang5,7
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View Affiliations Hide AffiliationsAffiliations: 1 Department of Laboratorial Science and Technology, School of Public Health, Peking University, Beijing, China 2 These authors contributed equally to this manuscript 3 School of Mathematical Sciences, Beijing Normal University, Beijing, China 4 Department of Biostatistics, College of Public Health and Health Professions, and Emerging Pathogens Institute, University of Florida, Gainesville, United States 5 State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China 6 School of Statistics, Beijing Normal University, Beijing, China 7 These senior authors contributed equally to this manuscriptLi-Qun Fangfang_lq 163.com
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Citation style for this article: Lu Qing-Bin, Zhang Yong, Liu Ming-Jin, Zhang Hai-Yang, Jalali Neda, Zhang An-Ran, Li Jia-Chen, Zhao Han, Song Qian-Qian, Zhao Tian-Shuo, Zhao Jing, Liu Han-Yu, Du Juan, Teng Ai-Ying, Zhou Zi-Wei, Zhou Shi-Xia, Che Tian-Le, Wang Tao, Yang Tong, Guan Xiu-Gang, Peng Xue-Fang, Wang Yu-Na, Zhang Yuan-Yuan, Lv Shou-Ming, Liu Bao-Cheng, Shi Wen-Qiang, Zhang Xiao-Ai, Duan Xiao-Gang, Liu Wei, Yang Yang, Fang Li-Qun. Epidemiological parameters of COVID-19 and its implication for infectivity among patients in China, 1 January to 11 February 2020. Euro Surveill. 2020;25(40):pii=2000250. https://doi.org/10.2807/1560-7917.ES.2020.25.40.2000250 Received: 06 Mar 2020; Accepted: 14 Jul 2020
Abstract
The natural history of disease in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remained obscure during the early pandemic.
Our objective was to estimate epidemiological parameters of coronavirus disease (COVID-19) and assess the relative infectivity of the incubation period.
We estimated the distributions of four epidemiological parameters of SARS-CoV-2 transmission using a large database of COVID-19 cases and potential transmission pairs of cases, and assessed their heterogeneity by demographics, epidemic phase and geographical region. We further calculated the time of peak infectivity and quantified the proportion of secondary infections during the incubation period.
The median incubation period was 7.2 (95% confidence interval (CI): 6.9‒7.5) days. The median serial and generation intervals were similar, 4.7 (95% CI: 4.2‒5.3) and 4.6 (95% CI: 4.2‒5.1) days, respectively. Paediatric cases < 18 years had a longer incubation period than adult age groups (p = 0.007). The median incubation period increased from 4.4 days before 25 January to 11.5 days after 31 January (p < 0.001), whereas the median serial (generation) interval contracted from 5.9 (4.8) days before 25 January to 3.4 (3.7) days after. The median time from symptom onset to discharge was also shortened from 18.3 before 22 January to 14.1 days after. Peak infectivity occurred 1 day before symptom onset on average, and the incubation period accounted for 70% of transmission.
The high infectivity during the incubation period led to short generation and serial intervals, necessitating aggressive control measures such as early case finding and quarantine of close contacts.
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