Risk of COVID-19 transmission from asymptomatic people

What is it about?

Some people infected with the novel coronavirus, or SARS-CoV-2, do not show any symptoms. This subgroup of patients is considered to be 'asymptomatic'. Although asymptomatic people appear to be healthy, they may still be a carrier of the virus and spread COVID-19 to other people. Indeed, these carriers may themselves not know that they are infected! Thus, tracking asymptomatic COVID-19 patients is crucial. However, it is not easy to do so. In the absence of reliable data, assessing the role of these people in viral transmission is complex, too. Hence, a 2020 paper decided to address this problem. The authors of this paper looked at the published data on SARS-CoV-2 infections, to see if asymptomatic carriers increased the risk of disease spread. They examined 13 studies which contained the most reliable evidence on disease spread. These 13 studies included data on about 21,708 people who had been tested for the virus. These people were all seen to be at risk of being infected with the virus. What did they find? 17% of all COVID-19 cases were asymptomatic at the time of their diagnosis. Such was the case at subsequent checkups too. This proportion was higher among patients in aged care. However, these asymptomatic people were 42% less likely to transmit COVID-19 to others, as compared to symptomatic cases.

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Photo by Martin Sanchez on Unsplash

Photo by Martin Sanchez on Unsplash

Why is it important?

COVID-19 is a highly contagious disease. It can (and has) easily spread among populations, resulting in disastrous outcomes. However, to control the disease's spread, we need to have detailed knowledge about its transmission. Hence, studies like this one (which highlights the prevalence of asymptomatic carriers and their potential to spread COVID-19) are very important. They provide crucial insights that can help safeguard public health, such as designing strategies to prevent transmission of the virus. KEY TAKEAWAY: Asymptomatic carriers may not pose a major public health threat because they are less likely to contribute to COVID-19 transmission. But more data from these carriers is needed to make a final verdict on this.