WASHINGTON: Scientists have known for several months that the new coronavirus can be suspended in droplets ejected by patients when they speak and breathe, but until now there was no evidence that these tiny particles were infectious.
A new study by scientists at the University of Nebraska who uploaded to a medical prepress site this week has shown for the first time that SARS-CoV-2 taken from microdroplets, defined as less than five microns, can replicate under conditions of laboratory.
This increases the hypothesis that speaking and breathing normally, not just coughing and sneezing, are responsible for spreading Covid-19, and that infectious doses of the virus can travel distances much greater than the six feet (two meters) required by the guidelines for social distance.
The results are still considered preliminary and have yet to appear in a peer-reviewed journal, which would give more credibility to the methods designed by the scientists.
The document was published in the medrxiv.org website, where most cutting-edge research during the pandemic was first made public.
The same team wrote an article in March that shows the virus lingers in the air in hospitalized rooms with Covid-19, and this study will soon be published in a journal, according to the lead author.
“It is actually quite difficult” to collect the samples, said Joshua Santarpia, an associate professor at the University of Nebraska Medical Center.
The team used a cell phone-sized device for this purpose, but “the concentrations are typically very low, their chances of recovering material are small.” Scientists took air samples from five bedridden patient rooms at a height of about one foot (30 centimeters) above the foot of their beds.
The patients were talking, producing microdroplets that are suspended in the air for several hours in what is known as an “aerosol,” and some coughed.
The team managed to collect small droplets one micron in diameter.
They then placed these samples in a culture to grow them, discovering that three of the 18 analyzed samples were able to replicate.
For Santarpia, this represents proof that microdroplets, which also travel much greater distances than large droplets, are capable of infecting people. “It replicates in cell culture and is therefore infectious,” he said.
The potential for coronavirus micro-droplet transmission at one time was considered by health authorities worldwide to be unlikely.
Later, scientists began to change their minds and recognize that it may be a possibility, which is the reason for universal masking.
The World Health Organization was one of the last to change its position, doing so on July 7.
“I feel like the debate has become more political than scientific,” said Santarpia.
“I think most scientists working on infectious diseases agree that there is likely to be a component in the air, although we could argue about how large it is.” Linsey Marr, a professor at Virginia Tech, a leading expert in airborne virus transmission and who was not involved in the study, said it was rare to get measurements of the amount of virus in the air.
“Based on what we know about other diseases and what we know so far about SARS-CoV-2, I think we can assume that if the virus is ‘infectious in aerosols,’ then we can become infected by inhaling them,” he said. said.
Posted in Dawn, July 23, 2020
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