US government scientists believe the new coronavirus is likely transmitted by people when they speak and breathe, a determination that leads to a logical conclusion: wearing masks or scarves can help curb contagion. The administration of Donald Trump is about to change its official instructions to encourage, but probably not force, the population to cover their faces in public, with handmade masks, scarves or bandanas, in order to reserve medical masks caregivers, shortage requires.
In New York, the mayor has already asked residents to cover their faces outside their homes, and as of Friday, just under half of pedestrians were applying the order in Manhattan, according to an observation by AFP journalists.
Read also: LIVE - Containment: "There will be no loosening of controls" warns Christophe Castaner
Seen from Asia, where surgical masks are omnipresent, the delay in Western countries is an aberration. But health authorities in the United States or France, as well as the World Health Organization, have argued so far that the mask is not necessary for healthy people, unless they are in contact with the sick. For several days, a flip-flop has been preparing, under pressure from an audience that does not understand why the masks would protect nurses but not ordinary citizens.
In France, the Academy of Medicine recommended Friday the compulsory wearing of the mask, as a "logical addition to the barrier measures" . And in the United States, on Friday, the director of the Institute of Infectious Diseases, Anthony Fauci, member of the White House working group on the coronavirus who says he spends an hour a day with President Trump, spoke on Fox News reports that "the virus can actually be transmitted when people are just talking, rather than just when they sneeze or cough" .
Transmission by air would provide a long-sought explanation for the apparent high contagiousness of the virus responsible for the Covid-19 pandemic, since it appears that infected but symptomless people, who represent perhaps a quarter of all infected people. , are responsible for a large part of the contagions, without their knowledge. Multiple studies have shown that asymptomatic people have infected people close to them in churches, in a choir or a singing class, in retirement homes ...
Read also: Coronavirus: the mayor of New York asks the population to cover their faces outside
What is the scientific evidence? There are few, but they converge. The American Academies of Sciences cited in a letter to the White House Wednesday four studies tipping the balance in favor of transmission of the virus via the air exhaled by people ("aerosols" in scientific jargon), and no longer only by the droplets and postlets projected during a sneeze directly on the face of other people or on surfaces (where the virus can survive for hours or even days, depending on the type of surface). "The research currently available supports the possibility that SARS-CoV-2 can be transmitted by bioaerosols generated directly by the exhalation of patients," writes Harvey Fineberg, chair of the committee on emerging infectious diseases. He points out that more is needed to better understand the real risk of infection. If the virus is actually present in respiration, it is not known whether this represents a significant route of transmission quantitatively.
In a study, researchers from the University of Nebraska found portions of the genetic code for the virus (RNA) in the air of rooms where patients were isolated. Researchers at the University of Hong Kong recently observed that wearing masks reduced the amount of coronavirus exhaled by patients (the experiment was done with viruses other than SARS-CoV-2). And researchers in Wuhan took air samples from various hospital rooms and found high concentrations of the new coronavirus, especially in the toilets and rooms where caregivers removed their protective gear.
In light of these results, the official change of orders in the United States is imminent, according to Vice President Mike Pence. It remains to know the formulation. "I don't think it will be mandatory," said Donald Trump on Thursday.
