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According to scientists from the University of Bern, the proportion of people infected with Covid 19 who do not experience any symptoms is around twenty percent. This arises from a report in the specialized journal “PLOS Medicine”.
If the number of people without symptoms were high, the so-called herd immunity should be achieved soon, according to one thesis. But: “This is very likely not the case,” says epidemiologist and last author of the study, Nicola Low, of the University of Bern.
The devil is in the details
So far, experts have disagreed on the extent of the infected without symptoms. Because the devil is in the details: If you’re infected with a single, symptom-free test, you can still develop symptoms later on; we speak of presymptomatic patients.
Low’s team has now evaluated 79 studies that examined infected people for symptoms over a long period between March and June. Consequently, out of 6,616 people, only 1,287 remained asymptomatic for the entire duration of the disease. In about 80 percent, however, symptoms appeared sooner or later.
Children affected less than adults
In a narrower selection of studies in which subjects were randomly selected, not just hospital patients, the number of asymptomatic infected people stabilized at 30 percent. The researchers also found that the disease manifests itself less frequently in children than in adults.
The overall study confirms that asymptomatically infected people play a relatively small role in the spread of the virus. The problem is presymptomatic patients who are not yet aware of their infection, Low says.
Wearing a mask and keeping your distance is important
Therefore, to stop the pandemic, it is of the utmost importance to constantly adhere to general measures, such as wearing a mask and keeping your distance.
Low and his team will keep an eye on the studies on the course of asymptomatic diseases; Since the completion of his review article, another 900 studies have been published that, according to the epidemiologist, could be relevant.
It is now known that the spectrum of symptoms is broader than initially assumed: in addition to coughing and shortness of breath, there was also loss of taste and smell, as well as pain in the extremities. With these new findings, the number of asymptomatic disease courses can be more precisely determined in the future. (SDA)
