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The controversy over whether covid-19 is transmitted by aerosols continues, now with a letter published this Monday in the journal Science, in which scientists say that “there is overwhelming evidence” in favor of inhaling Sars- Cov-2 “represents a major route” of disease transmission.
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The letter is signed by scientists from several American universities, such as those of San Diego, Maryland, Virginia Tech and headed by Kimberly Prather, from La Jolla University.
Although there is agreement that COVID-19 is transmitted through large droplets of saliva that we expel when coughing or sneezing, there is still no unanimity on whether the contagion is also produced by aerosols, that is, much smaller drops that can travel further. and stay suspended in the air longer.
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Aerosol viruses “can remain suspended in the air for many seconds or hours, like smoke, and be inhaled”, they are also “highly concentrated near an infected person, so they can more easily infect people who are close “, they indicate.
But, in addition, aerosols containing infectious viruses “can also travel more than two meters and accumulate in poorly ventilated indoor air, leading to over-diffusion events.”
Therefore, in addition to the use of masks, the safety distance and hygiene efforts, the researchers urge those responsible for public health to “articulate the importance of moving activities to the outside, improving indoor air using ventilation and filtration , and improve the protection of high-risk workers. “
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It is important that people wear masks “at all times in public buildings and confined spaces”, not just when a safe distance cannot be maintained.
“It is not just an academic question, but a point that will help reduce transmission if public health officials offer clear and forceful guidance on this,” says Linsegy Marr, another of the signatories and from Virginia Tech University. quoted in a statement.
The purpose of this letter, Prather notes, “is to make clear that the Sars-Cov-2 virus travels through the air and that people can become infected by inhalation.”
For this reason, he considers that “it is important to recognize” this transmission route “so that efforts are focused on cleaning the air and providing guidance on how to avoid risky indoor environments.”
In addition, the authors propose to seek a consensus in the controversy about aerosol transmission and point out the “urgent need to harmonize the debates on the modes of transmission of viruses in all disciplines, to guarantee more effective control strategies and provide guidance clear and consistent to the public. ”
Thus, they write that the scientific community must clarify the terminology used in relation to aerosols and droplets, and use a more modern size threshold, rather than the existing one based on work from the 1930s.
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The proposal to distinguish between aerosols and droplets is to take the size threshold of 100 micrometers as a measure instead of the traditional 5 micrometers.
This size – they consider – “more effectively separates its aerodynamic behavior, the capacity to be inhaled and the effectiveness of the interventions”.
Those responsible for public health “should make a clear distinction between the droplets expelled by coughing or sneezing” and the aerosols that, they say, can transport the virus to “much greater” distances.
Viruses in aerosols smaller than 100 microns, they say, can remain in the air in a confined space for long periods of time and accumulate in the environment.
poorly ventilated air, which leads to transmission.
EFE
