WASHINGTON | A group of 239 international scientists has called on Monday, the health authorities of the planet and in particular the world health Organization (WHO) to recognize that the coronavirus may be spread through the air well in excess of two metres and recommend, therefore, a breakdown strength of public spaces.
Their letter refers directly to the un agency, already criticized for having been slow to recommend the masks, and here accused of refusing to see the accumulation of clues spread through the air virus that has killed more than 500, 000 people in the world in six months.
The WHO and other health agencies believe that the coronavirus is primarily transmitted by droplets projected by coughing, sneezing and speaking directly into the faces of people close to, and possibly through the surfaces where these spatters are landing and are then picked up by the hands of healthy people. These droplets are heavy and fall within a radius of about one meter.
Hence the priority given in the safety instructions, to detachment physical, hand washing and wearing a mask.
But studies on the SARS-CoV-2, and other respiratory viruses, showed that viral particles were also present in microscopic droplets (less than 5 microns in diameter) in the air exhaled by an infected person; more light, they can remain in suspension in the interior, potentially hours, and be inspired by other people. It has never been proven that these particles of coronavirus were viable and could cause infection; but the clues are accumulating.
“We call on the medical community and national and international agencies with the ability to recognize the potential of air-borne transmission of the COVID-19 “, write in the journal Clinical Infectious Diseases Oxford two scientists, Lidia Morawska, University of Queensland (Australia) and Donald Milton of the University of Maryland, in an article signed by 237 other experts.
“There is a significant potential of risk of inhalation of virus contained in respiratory droplets, from microscopic (micro-droplet) to short and middle distance (up to several meters, of the order of the scale of a room), and we advocate the use of preventive measures to prevent this route of transmission air”, they write.
Renew the air
There is no scientific consensus that air plays a role in the contagion: but Julian Tang, one of the signatories, of the University of Leicester, explained that WHO has not proved the opposite: “The absence of evidence is not evidence of absence.”
At the time of the déconfinement, there is an urgent need, argue the experts, better to ventilate working places, schools, hospitals and retirement homes, and install tools to fight infections such as air filters, sophisticated and ultraviolet rays special that kill the germs in the ventilation ducts.
The authorities in the United States and Europe are ahead of the WHO. “Increase the flow of outside air as much as possible,” advise the Centres for prevention and disease control (CDC) in the united states.
The CDC european explained, the 22 June, that the air conditioning could dilute the virus into the air and explode, but that it could have the opposite effect if the ventilation system is not renewed is no air and was recirculated in the same parts.
A famous example is that of a cluster that started in a restaurant in Canton in January: a person without symptoms has affected customers of two neighbouring tables, non-contact; the air conditioner has probably made to steal the virus from one table to another table.
Other cases of supercontagions, in a coach and a chinese in a choir american, accredited also the track in the air.
“The transmission by air of SARS-CoV-2 is not universally accepted; but our collective opinion is that there is enough evidence to apply the precautionary principle”, the scientists say.
WHO makes the distinction between viruses transmitted by air, such as measles and tuberculosis, and the other, but “this is not a problem of dichotomy”, told AFP another signatory, professor Caroline Duchaine, director of the laboratory on bioaerosols at the University of Laval in Quebec.
“We made a mistake if there is an opposition between the transmission of the virus, such as measles and by the COVID-19,” she said.