A Cluster of COVID-19 Infections Indicating Person-To-Person Transmission among Casual Contacts from Social Gatherings: An Outbreak Case-Contact Investigation

19 Pages Posted: 2 Apr 2020

See all articles by Ye Shen

Ye Shen

University of Georgia

Wenjie Xu

Ningbo University - Medical School

Changwei Li

University of Georgia - Department of Epidemiology and Biostatistics

Andreas Handel

University of Georgia - Department of Epidemiology and Biostatistics

Leonardo Martinez

Stanford University - Division of Infectious Diseases and Geographic Medicine

Feng Ling

Zhejiang Provincial Center for Disease Control and Prevention

Mark Ebell

University of Georgia - Department of Epidemiology and Biostatistics

Xiaofei Fu

Jiaxing Municipal Center for Disease Control and Prevention

Jinren Pan

Zhejiang Provincial Center for Disease Control and Prevention

Jiangping Ren

Zhejiang Provincial Center for Disease Control and Prevention

Weiling Gu

Jiaxing Municipal Center for Disease Control and Prevention

Enfu Chen

Zhejiang Provincial Center for Disease Control and Prevention

Date Written: March 28, 2020

Abstract

SARS-CoV-2, the pathogen causing COVID-19, efficiently spreads from person to person in close contact settings. Transmission among casual contacts in settings such as during social gatherings is not well understood. We report several transmission events to both close and casual contacts from a cluster of seven COVID-19 cases occurring from mid-January to early February. A total of 539 social and family contacts of the index patient’s, including members of a two-day wedding and a family party, were contacted and screened through epidemiologic surveys. The clinical progression of all cases is described. We estimate the secondary attack rate among close contacts to be 29%(2/7) and for the casual contacts to be 0.6%(3/473). The incubation period of our case cluster was 4–12 days (median, 7 days). Transmission efficiency among close contacts was higher than among casual contacts; however, transmission from second-generation cases may help spread the virus during the incubation period.

Note: Funding: No funding was received for this research.

Conflict of Interest: None.

Ethical Approval: The study was approved by the Institute Review Board at the Zhejiang Provincial CDC.

Keywords: COVID-19, cluster, casual contact, social gathering, attack rate

JEL Classification: I1

Suggested Citation

Shen, Ye and Xu, Wenjie and Li, Changwei and Handel, Andreas and Martinez, Leonardo and Ling, Feng and Ebell, Mark and Fu, Xiaofei and Pan, Jinren and Ren, Jiangping and Gu, Weiling and Chen, Enfu, A Cluster of COVID-19 Infections Indicating Person-To-Person Transmission among Casual Contacts from Social Gatherings: An Outbreak Case-Contact Investigation (March 28, 2020). Available at SSRN: https://ssrn.com/abstract=3563064 or http://dx.doi.org/10.2139/ssrn.3563064

Ye Shen (Contact Author)

University of Georgia ( email )

101 Buck Rd
Athens, GA GA 30602
United States
30602 (Fax)

Wenjie Xu

Ningbo University - Medical School

818 Fenghua Road
Ningbo, 315211
China

Changwei Li

University of Georgia - Department of Epidemiology and Biostatistics ( email )

Athens, GA
United States

Andreas Handel

University of Georgia - Department of Epidemiology and Biostatistics

Athens, GA
United States

Leonardo Martinez

Stanford University - Division of Infectious Diseases and Geographic Medicine

Stanford, CA
United States

Feng Ling

Zhejiang Provincial Center for Disease Control and Prevention

Binjiang
Hangzhou, Zhejiang 310051
China

Mark Ebell

University of Georgia - Department of Epidemiology and Biostatistics

Athens, GA
United States

Xiaofei Fu

Jiaxing Municipal Center for Disease Control and Prevention

Jiaxing
China

Jinren Pan

Zhejiang Provincial Center for Disease Control and Prevention

Binjiang
Hangzhou, Zhejiang 310051
China

Jiangping Ren

Zhejiang Provincial Center for Disease Control and Prevention

Binjiang
Hangzhou, Zhejiang 310051
China

Weiling Gu

Jiaxing Municipal Center for Disease Control and Prevention

Jiaxing
China

Enfu Chen

Zhejiang Provincial Center for Disease Control and Prevention

Binjiang
Hangzhou, Zhejiang 310051
China

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