Columbia University scientists conducted a study to find out why the new SARS-CoV2 virus is spreading so rapidly around the world.
The results were published in the journal Science: from the very beginning, there were a large number of patients in China who were unaware of their illness, which had mild symptoms. Accordingly, these patients have not been identified for a long time, and the virus is highly contagious.
Using mathematical modeling, scientists compared data on reported cases of coronavirus infection in China and data on movement of people and found that 86 percent of cases were not documented. This contributed to the rapid geographical spread of the SARS-CoV2 virus.
According to study leader Jeffrey Shaman, “undetected infections can expose a much larger portion of the population to the virus than was thought. We found that there were many such undetected infected and highly contagious people in China.” The transmission rate from asymptomatic patients is 55 percent compared with patients with clear symptoms of the disease. In 79 percent of cases of infection, the sources could be carriers of the virus with no evidence of disease.
Only on January 23, 2020, restrictions on entry and exit from Wuhan were introduced, the information machine started working, the population received instructions on how to protect themselves from the virus. And from this moment, a significant decrease in the spread of SARS-CoV2 has been recorded.
The importance of this study is that it becomes obvious the need for major changes in the practice of documenting patients seeking medical care even with symptoms of a common respiratory infection. The effectiveness of measures to limit travel, the use of personal protective equipment and wide public awareness is also confirmed. Scientists urge authorities in countries where SARS-CoV2 is not yet widely available to take these results into account.
These measures have helped China reduce the spread of the infection, but it is not yet clear whether this reduction will be sufficient to completely stop the spread of the virus.
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