The epidemiologist, on the other hand, prefers to insist on the major role of the mask, which appears all the more useful when studying the functioning of the virus. SARS-CoV-2, she recalls, “is transmitted mainly by aerosols, a term that refers to a mixture of liquid and solid particles with a size of less than 5 micrometers”. The Covid is between 70 and 130 nanometers, “which allows it to remain suspended in the air: this is normal, since the heaviest particles will be those which will quickly fall to the ground”.
In enclosed indoor spaces, “the virus remains”, insists the expert. Multiple studies have also proven it, she reports. The researchers even observed that, to a lesser extent, diffusion could be observed in the air outside. Aerosols, scientists agree today to say, “is the most important mode of propagation”. Nothing surprising, says Isabella Annesi-Maesano, since these observations are reminiscent of those made with other viruses. “Measles is the same. Tuberculosis, the flu virus… Or also the cold one.”
Has the appearance of new variants over time changed the situation? “Non”, decides the representative of Inserm, who today advocates for the wearing of a mask and the ventilation of closed places. Gestures that are all the more important in his eyes as “one does not necessarily need to show symptoms to spread the virus in the event of contamination”. It is propagated like this “when we speak, we laugh, we sing… As soon as we exhale air, in short.” And to remember that work carried out by German and American researchers has (like others before them) proven the very great effectiveness of the mask in preventing transmission. “They have shown very well that when two people, including one infected, put on a mask, the risk of contamination remains minimal.” So that a healthy person is very largely protected, including in the presence of positive people.