While the possibility of a second wave of the epidemic is becoming clearer, American researchers from the University of Nebraska believe that the air exhaled by a patient is undoubtedly infectious.
We know a little more about the dangerousness of coronavirus in the air. The coronavirus causing Covid-19 has been found for months on multiple objects in hotel or hospital rooms, as well as suspended in the air, but until a pre-published study this week, it did not aerosolized virus particles had never been shown to be sufficiently intact to replicate and cause infection.
Transmitted by exhaled air?
A team from the University of Nebraska has for the first time succeeded in replicating SARS-CoV-2 particles collected from the air in rooms of patients with Covid-19, boosting the hypothesis that the virus is transmissible not only by the postilions and large droplets emitted by coughing and sneezing, but also by the microscopic droplets that we release when we breathe and speak, and which are so light that they stay in suspension for a long time, in the absence ventilation.
The results are preliminary and have not been reviewed by the reading committee of a scientific journal, which will have to confirm that the method used by the scientists is valid. They were posted on Monday on the site medrxiv.org, where the scientific community can freely comment on them. But the same team had pre-published in March a study showing that the virus remained in the air of hospital rooms of patients, and this article will soon be published by a scientific journal, according to the lead author.
“It’s not easy,” says Joshua Santarpia, professor at the University of Nebraska Medical Center, of the method of collecting virus particles in the air, using a device the size of a cell phone. “The concentrations are low, generally there is little chance of recovering usable samples.”
Air taken from sick rooms
The researchers sampled the air in the rooms of five bedridden patients, about 30 cm above their feet. The patients were talking, some were coughing. Scientists have managed to collect microdroplets less than five microns in diameter containing virus, and even less than one micron.
They then isolated the virus and placed it in a special medium to make it replicate. They only managed to replicate with certainty only three of the 18 samples, coming from one micron droplets.
But Joshua Santarpia is sure: “it replicates in cell culture and is therefore infectious.”
Evidence emerges for airborne transmission
The airborne route of transmission was considered improbable at the start of the pandemic by health authorities in several countries and the World Health Organization, who believe that direct contamination (by spray and droplets directly projected on the face) remains the way main contagion. But the WHO, under pressure from scientists, recognized on July 7 that evidence was emerging on airborne transmission.
“The debate has become more political than scientific, I believe most infectious disease scientists agree that the airway is a component of transmission, although we are still debating its importance,” says Joshua Santarpia.
Airborne virus transmission specialist Professor Linsey Marr commented on Twitter that the study presented “strong evidence,” adding: “There is infectious virus in the air. It remains to be seen how much to take. breathe to get infected “.
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