A new study published in the journal Science tracked the spread of the new coronavirus SARS-CoV-2 in China in January this year and concluded that 86% of early infections were not recorded.
Researchers believe that only active identification and tracking of asymptomatic infections can play a vital role in slowing the spread of the epidemic.
Figure-1: Best fit model and sensitivity analysis.
The new study brings together scientists from Columbia University, Imperial College London, UC Davis, and the University of Hong Kong to analyze case reports from January 10 to 23 in 375 cities across the country.
Using computer models to simulate the spatiotemporal spread of the virus, the research team came to a conclusion that focusing on confirmed cases alone could not explain the spread of the new coronavirus in China this January.
In fact, the model shows that 86% of infected people were not recorded during this time. Research co-author Jeffrey Shaman of Columbia University's School of Posts and Letters states:
The COVID-19 outbreak in China was largely driven by undetected mild or asymptomatic infected individuals.
Based on the infectivity of the new coronavirus and the number of tests, undetected cases could expose a greater percentage of the population to the threat.
In addition, we found that these asymptomatic infections are not only large in number, but also quite concealed and infectious, posing a major challenge to curbing the outbreak.
Figure-2: Effect of asymptomatic infection on SARS-CoV-2 transmission.
The study adds that, although these asymptomatic infections are less infectious than confirmed cases (estimated to be only about half of infectious cases), they may lead to 79% of recorded cases subsequently.
After the implementation of strict control measures in China, the second infection tracking simulation from January 24 to February 8 showed that the number of unrecorded cases has decreased significantly.
Obviously, this confirms the importance of implementing social alienation and extensive testing throughout the community.
With increasing awareness of prevention and control in various sectors, measures such as personal hygiene cleaning and travel restrictions will help reduce the overall number of infections, but it is unclear whether these actions are sufficient to completely stop the spread of the new coronavirus.
Details of the research have been published in the recently published Science journal titled "Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV2)."
Earlier, Imperial College London has carried out research on the infectivity of the COVID-19 virus based on data starting in February, and the results indicate that there may be 2/3 of cases worldwide undetected.
This means that indeed many people may be infected with COVID-19, but the spread of the virus is difficult to control or track due to mild or no obvious symptoms.
In the latest media briefing, Tedros Adhanom Ghebreyesus, Director-General of the WHO, reiterated the two most important things at the moment, that everyone should socially alienate and expand the scope of testing in various countries.
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