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HomeHealth ConditionsCOVID-19Are undiagnosed cases of COVID-19 driving the fast spread of the outbreak?

Are undiagnosed cases of COVID-19 driving the fast spread of the outbreak?

A new study suggests undiagnosed cases of COVID-19 may be responsible for the rapid spread of the coronavirus outbreak.

The coronavirus disease, also known as COVID-19, first emerged in Wuhan, China in 2019. As of March 19, 2020, this novel coronavirus (SARS-CoV-2) has spread to 177 countries. Researchers from around the world are working to find ways to contain to prevent and treat the virus.

Researchers from Columbia University, suggest that the undiagnosed cases of COVID-19 may be driving the rapid spread of the outbreak. In the study, published in Science, the researchers developed a computer model that simulated observations of reported infections across 375 cities in China in conjunction with mobility data. In this model, the observations were divided into diagnosed and undiagnosed cases of COVID-19. Mobility data was made up of information obtained on the number of people travelling daily between cities. The researchers applied the model to the observed COVID-19 outbreaks from January 10 to 23 before the travel restrictions were imposed on January 23 and then between January 24 and February 8.

The study reports that about 86 percent of COVID-19 cases were undiagnosed prior to the travel restrictions. The undiagnosed cases of COVID-19 were estimated to be around half as contagious as the diagnosed cases. However, because of their higher numbers, the undiagnosed cases were found to be the source of approximately 80 percent of transmission. The study also reported that improved population awareness of the outbreak, increased use of personal protective measures, and travel restrictions helped reduced the rate at which the virus spread.

The findings suggest that the undiagnosed cases of COVID-19 were responsible for the rapid spread of the outbreak, making containment of the virus a significant challenge. According to study author, Dr. Shaman, individuals with mild or no symptoms who went undetected facilitated the quick spread of the virus. Dr. Shaman suggests that the undiagnosed cases may expose a greater segment of the population to the virus than would otherwise occur.

According to the researchers, if COVID-19 follows the pattern of the 2009 H1N1 pandemic influenza, then it may also spread worldwide and could potentially become the fifth endemic coronavirus among the human population.

Written by Ranjani Sabarinathan, MSc                                                                                      

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Li R, Pei S, Chen B et al. (2020). Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV2). Science. doi: 10.1126/science.abb3221

‘Stealth transmission’ fuels fast spread of coronavirus outbreak. (2020, March 16). Retrieved from

Image by Engin_Akyurt from Pixabay 




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