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Substantial Undocumented Infection Facilitates the Rapid Dissemination of Novel Coronavirus (SARS-CoV-2)
Article

Substantial Undocumented Infection Facilitates the Rapid Dissemination of Novel Coronavirus (SARS-CoV-2)

Science, 2020

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People who show no symptoms of novel coronavirus (SARS-CoV-2) must still adhere to local control measures, to ensure the protection of vulnerable human populations. As researchers found, the virus freely circulated for weeks in Wuhan City, China, spread by people who were largely asymptomatic. In fact, an astounding 79% of initial infections occurred due to exposure to undocumented viral carriers. This in some part accounts for the rapid global spread of SARS-CoV-2, and makes its containment extremely challenging.

Summary

People who do not know they are carriers of novel coronavirus (SARS-CoV-2) can heavily contribute to its rapid spread.

The novel coronavirus that inundated Wuhan, China in late 2019 rapidly spread to 58 additional countries. Understanding the contagiousness of this virus is critical to controlling the disease it causes.

[Editor’s Note: Coronavirus disease 2019 (COVID-19) is an infectious viral respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as “novel coronavirus.”]

Scientists studied original observations of the pandemic in China, plus mobility data, a metapopulation model, and Bayesian inference, to find out how undocumented infections contributed to its aggressive dissemination.

Their data indicated that about 86% of all infections before China’s January 23 travel restrictions were initiated were undocumented. They also found that an astounding 79% of initial infections occurred due to exposure to undocumented, asymptomatic carriers. This explains the rapid viral spread in human populations, and makes controlling infections exceedingly difficult.

About the Authors

Authors include Ruiyun Li, MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College, London; Sen Pei, Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York; Bin Chen, Department of Land, Air and Water Resources, University of California, Davis; Yimeng Song, Department of Urban Planning and Design, The University of Hong Kong; Tao Zhang, Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing; Wan Yang, Department of Epidemiology, Mailman School of Public Health, Columbia University, New York; and Jeffrey Shaman, Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York.


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