The answer appears to have come in a new study published in the Journal of the American Medical Association. In this, the authors assure that asymptomatic cases can spread the disease, and that, in fact, they are responsible for at least 50 percent of new infections.
Presymptomatic, asymptomatic and symptomatic
The researchers modeled three groups of transmitters of the SARS-CoV-2 coronavirus based on the presence of their symptoms. These were: presymptomatic cases, that is, people who had not experienced symptoms; cases that never developed symptoms; and, of course, those who did.
The goal was to determine how much COVID-19 each group would spread depending on the day the people in them were most infectious; For this, they took into account several scenarios.
One of them was that 30 percent of people were asymptomatic and that those people were 75 percent as infectious as the people who showed them or who would show them at some point. This simulation found that asymptomatic cases were responsible for 24 percent of new infections.
Asymptomatic COVID-19 Cases Are Responsible For Much Of New Infections
Initially, the researchers assumed that the point at which all people would be most infectious would be five days after exposure to the pathogen. This is following the scientific findings that suggest that this is the mean incubation time, that is, the period it takes for symptoms to appear.
But in the other scenarios they raised different points in which there would be more capacity to spread the infection: three, four, six and seven days; In addition, they reduced and increased the percentage of asymptomatic patients with COVID-19 to see how these cases are related to new infections.
This is how they discovered that people without symptoms (both asymptomatic and presymptomatic) transmit at least 50 percent of new COVID-19 infections.
These results are consistent with previous estimates made by the Centers for Disease Control and Prevention (CDC). Their studies had previously suggested that asymptomatic cases could transmit the disease at a similar rate.
Presymptomatic individuals appear to be the largest transmitters of new COVID-19 infections
"The transmission rate remained generally above 50 percent over a wide range of base values," said Jay Butler, CDC's deputy director of infectious diseases and lead author of the new study.
Although the presymptomatic appears to be a group that deserves more attention. In the scenario where the peak of transmission occurred seven days after exposure, asymptomatic cases were responsible for 0 percent of new COVID-19 infections. In contrast, the presymptomatic group caused more than 25 percent of the cases overall.
The importance of continuing the use of masks and physical distancing
Butler emphasizes that these findings remind us of the importance of following the preventive recommendations against the coronavirus, especially the use of masks and social distancing.
"This study shows that while symptom detection may have some value, mitigation, as well as strategically planned testing of people in some setting, will be of significant benefit."
Despite the fact that there are many studies that confirm the effectiveness of these methods, there is still much discontent in having to continue them. But we must remember that even though vaccines have begun to be distributed, the process is slow and there are mutations that are causing concern among scientists.
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