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Modes of Contact and Risk of Transmission in COVID-19: A Prospective Cohort Study 4950 Close Contact Persons in Guangzhou of China

40 Pages Posted: 9 Apr 2020

See all articles by Lei Luo

Lei Luo

Guangzhou Center for Disease Control and Prevention

Dan Liu

Southern Medical University - Department of Epidemiology

Xin-long Liao

Guangzhou Center for Disease Control and Prevention

Xian-Bo Wu

Southern Medical University - Department of Epidemiology

Qin-long Jing

Guangzhou Center for Disease Control and Prevention

Jia-zhen Zheng

Southern Medical University - Department of Epidemiology

Fang-hua Liu

Guangzhou Center for Disease Control and Prevention

Shi-gui Yang

Zhejiang University - State Key Laboratory for Diagnosis and Treatment of Infectious Diseases

Bi Bi

Guangzhou Center for Disease Control and Prevention

Zhi-Hao Li

Southern Medical University - Department of Epidemiology

Jian-ping Liu

Guangzhou Center for Disease Control and Prevention

Wei-qi Song

Southern Medical University - Department of Epidemiology

Wei Zhu

Guangzhou Center for Disease Control and Prevention

Zheng-he Wang

Southern Medical University - Department of Epidemiology

Xi-Ru Zhang

Southern Medical University - Department of Epidemiology

Pei-Liang Chen

Southern Medical University - Department of Epidemiology

Hua-Min Liu

Southern Medical University - Department of Epidemiology

Xin Cheng

Southern Medical University - Department of Epidemiology

Miao-chun Cai

Southern Medical University - Department of Epidemiology

Qing-mei Huang

Southern Medical University - Department of Epidemiology

Pei Yang

Southern Medical University - Department of Epidemiology

Xing-fen Yang

Southern Medical University - Food Safety and Health Research Center

Zhi-gang Han

Guangzhou Center for Disease Control and Prevention

Jinling Tang

The Chinese University of Hong Kong (CUHK) - School of Public Health and Primary Care

Yu Ma

Guangzhou Center for Disease Control and Prevention

Chen Mao

Southern Medical University - Department of Epidemiology

More...

Abstract

Background: Rapid spread of SARS-CoV-2 in Wuhan prompted heightened surveillance in Guangzhou and elsewhere in China. Modes of contact and risk of transmission among close contacts have not been well estimated.

Methods: We included 4950 closes contacts from Guangzhou, and extracted data including modes of contact, laboratory testing, clinical characteristics of confirmed cases and source cases. We used logistic regression analysis to explore the risk factors associated with infection of close contacts.

Findings: Among 4950 closes contacts, the median age was 38.0 years, and males accounted for 50.2% (2484). During quarantine period, 129 cases (2.6%) were diagnosed, with 8 asymptomatic (6.2%), 49 mild (38.0%), and 5 (3.9%) severe to critical cases. The sensitivity of throat swab was 71.32% and 92.19% at first to second PCR test. Among different modes of contact, household contacts were the most dangerous in catching with infection of COVID-19, with an incidence of 10.2%. As the increase of age for close contacts and severity of source cases, the incidence of COVID-19 presented an increasing trend from 1.8% (0-17 years) to 4.2% (60 or over years), and from 0.33% for asymptomatic, 3.3% for mild, to 6.2% for severe and critical source cases, respectively. Manifestation of expectoration in source cases was also highly associated with an increased risk of infection in their close contacts (13.6%). Secondary cases were in general clinically milder and were less likely to have common symptoms than those of source cases.

Interpretation: The proportion of asymptomatic and mild infections account for almost half of the confirmed cases among close contacts. The household contacts were the main transmission mode, and clinically more severe cases were more likely to pass the infection to their close contacts. Generally, the secondary cases were clinically milder than those of source cases.

Funding Statement: Supported by the Project Supported by Guangdong Province Higher Vocational Colleges & Schools Pearl River Scholar Funded Scheme (2019), the Construction of High-level University of Guangdong (G619339521 and G618339167), and the Zhejiang University special scientific research fund for COVID-19 prevention and control (K920330111)

Declaration of Interests: None.

Ethics Approval Statement: Ethics approval was obtained from the Ethics Committee of Southern Medical University. Data collection and analysis of close contacts and source cases were also required by the National Health Commission of the People's Republic of China to be part of a continuing public health outbreak investigation. Written informed consent was waived in light of the urgent need to collect data.

Keywords: COVID-19, close contacts, modes of contact, risk of transmission

Suggested Citation

Luo, Lei and Liu, Dan and Liao, Xin-long and Wu, Xian-Bo and Jing, Qin-long and Zheng, Jia-zhen and Liu, Fang-hua and Yang, Shi-gui and Bi, Bi and Li, Zhi-Hao and Liu, Jian-ping and Song, Wei-qi and Zhu, Wei and Wang, Zheng-he and Zhang, Xi-Ru and Chen, Pei-Liang and Liu, Hua-Min and Cheng, Xin and Cai, Miao-chun and Huang, Qing-mei and Yang, Pei and Yang, Xing-fen and Han, Zhi-gang and Tang, Jinling and Ma, Yu and Mao, Chen, Modes of Contact and Risk of Transmission in COVID-19: A Prospective Cohort Study 4950 Close Contact Persons in Guangzhou of China (3/29/2020). Available at SSRN: https://ssrn.com/abstract=3566149 or http://dx.doi.org/10.2139/ssrn.3566149

Lei Luo (Contact Author)

Guangzhou Center for Disease Control and Prevention ( email )

Dexing 1st Cross Street
Guangzhou, Guangdong 510440
China

Dan Liu

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Xin-long Liao

Guangzhou Center for Disease Control and Prevention

Dexing 1st Cross Street
Guangzhou, Guangdong 510440
China

Xian-Bo Wu

Southern Medical University - Department of Epidemiology ( email )

Guangzhou, 510515
China

Qin-long Jing

Guangzhou Center for Disease Control and Prevention

Dexing 1st Cross Street
Guangzhou, Guangdong 510440
China

Jia-zhen Zheng

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Fang-hua Liu

Guangzhou Center for Disease Control and Prevention

Dexing 1st Cross Street
Guangzhou, Guangdong 510440
China

Shi-gui Yang

Zhejiang University - State Key Laboratory for Diagnosis and Treatment of Infectious Diseases

China

Bi Bi

Guangzhou Center for Disease Control and Prevention

Dexing 1st Cross Street
Guangzhou, Guangdong 510440
China

Zhi-Hao Li

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Jian-ping Liu

Guangzhou Center for Disease Control and Prevention

Dexing 1st Cross Street
Guangzhou, Guangdong 510440
China

Wei-qi Song

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Wei Zhu

Guangzhou Center for Disease Control and Prevention

Dexing 1st Cross Street
Guangzhou, Guangdong 510440
China

Zheng-he Wang

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Xi-Ru Zhang

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Pei-Liang Chen

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Hua-Min Liu

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Xin Cheng

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Miao-chun Cai

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Qing-mei Huang

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Pei Yang

Southern Medical University - Department of Epidemiology

Guangzhou, 510515
China

Xing-fen Yang

Southern Medical University - Food Safety and Health Research Center

China

Zhi-gang Han

Guangzhou Center for Disease Control and Prevention ( email )

Dexing 1st Cross Street
Guangzhou, Guangdong 510440
China

Jinling Tang

The Chinese University of Hong Kong (CUHK) - School of Public Health and Primary Care ( email )

Hong Kong
China

Yu Ma

Guangzhou Center for Disease Control and Prevention ( email )

Dexing 1st Cross Street
Guangzhou, Guangdong 510440
China

Chen Mao

Southern Medical University - Department of Epidemiology ( email )

Guangzhou, 510515
China

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