US, WASHINGTON (ORDO NEWS) — More research, including a recent publication in the journal Nature, is arguing that coronavirus remains in the air as aerosol particles. Although this evidence cannot be considered irrefutable, and the cases of such transmission are not documented, still questions arise about the mechanisms of infection.
So far, it is generally accepted that the virus, although very contagious, spreads through the droplets that form when breathing, talking or coughing, but does not infect people with particles that stay in the air for several hours, unlike a number of other diseases like measles.
However, the study sparked a scientific discussion on one of the most pressing issues around the new coronavirus – and, in an alarming time, when the nerves are at the limit. Outbreaks in crowded places – prisons, meat processing plants, cramped call centers and restaurants – signal the risks posed by the removal of isolation.
The scientific literature is full of troubling questions: is the virus transmitted through ventilation? And when you take off your clothes, do you not shake the virus particles back into the air?
Studies show that the virus is usually transmitted from person to person through relatively large respiratory drops that fly just a few meters and quickly settle to the ground. You can get infected by touching the first contaminated object – fomit, if in a scientific way – and then the face.
“There have been no cases of airborne transmission, and, as is clear from the available data, it is not the main force of the epidemic,” concluded researchers from China and the World Health Organization in a large-scale February study.
However, it was noted in it that with a number of medical procedures, for example, with intubation, viral aerosols are created. And studies in the Rocky Mountains Laboratory under the auspices of the National Institute of Allergy and Infectious Diseases showed that the volatile particles of the virus sprayed with special equipment retain the ability to multiply in cell culture, even after spending up to three hours in the air.
An article by scientists from Wuhan University in the journal Neutscher reported that aerosol traces with traces of viral genetic material, the so-called RNA component, were found in two hospitals, especially in poorly ventilated rooms. The highest concentration of volatile particles was in a portable toilet, where there was no ventilation. The RNA component was also found in the compartment where hospital workers removed protective equipment and changed clothes.
However, the article does not report whether the volatile particles of the virus were viable, that is, whether they can generate a new infection.
“Although it was not possible to establish the infectiousness of the virus found in hospital rooms, we suggest that SARS-CoV-2 can also be transmitted through aerosol particles,” the authors write. “Our results show that room ventilation, open spaces, disinfection of protective clothing, and proper use and disinfection of toilet areas successfully reduce the concentration of SARS-CoV-2 RNA in aerosols.”
Andrew Noymer, an epidemiologist at the University of California, Irvine, believes that the public should be wary of the new Chinese study because the PCR (polymerase chain reaction) test does not distinguish between a viable virus and non-infectious genetic material.
“The test for the viability of the virus – it is more precisely and is done on cell culture – was not conducted in this study,” said Neumer.
An alarming message came from a restaurant in Guangzhou, China, where one asymptomatic carrier allegedly infected nine. Scientists have suggested that the transmission of viral aerosol between tables is accelerated by ventilation.
“It just shows how terrible the confusion is from the common misconception that there is a fundamental difference between aerosol and respiratory drops,” said Donald Milton, professor of hygiene at the University of Maryland School of Public Health. “In fact, it’s all breathing drops, but of a different size, just some more and others less, up to microdrops with a diameter of less than a micron.” However, larger droplets in the air stream will behave like aerosols and for some time resist the force of attraction.”
According to a study in a South Korean call center on the 11th floor of a high-rise building, 94 people were infected in one outbreak, with most cases concentrated in one half of the office. The outbreak emphasizes, the authors write, that the virus is “extremely contagious in crowded conditions, for example, in a crowded office like the aforementioned center.”
But this does not at all follow that the virus was transmitted with an aerosol.
“I look at this with skepticism. As far as I know, we have not yet seen convincing evidence, ”says Angela Rasmussen, a virologist at Columbia University’s School of Public Health at the Mailman School of Columbia University. – Cases in a call center and restaurant suggest that regular airborne droplets in closed or poorly ventilated rooms are fraught with infection in and of themselves. It makes no sense to separately consider fine aerosols. ”
To test whether the virus is transmitted with aerosol particles, researchers will have to grow a living virus from these samples. Viral RNA is not enough – it may be residual genetic material that is not capable of causing infection.
In a yet peer-reviewed study at the University of Nebraska Medical Center, viral RNA was found on the surfaces of mobile phones, toilets, nightstands and exercise machines – they were used by 13 patients who confirmed coronavirus. Viral RNA was also found in the samples from outside hospital rest, however, scientists could not uniquely determine their infectivity.
Outsiders are skeptical of this disparate data.
Vincent Munster, a virologist at the Rocky Mountain Laboratory and coronavirus aerosol research director, does not rule out the possibility that aerosol particles can spread the disease, but suggests that their role in the pandemic is negligible.
“The question is: what is the driving force behind the pandemic now? If it is mainly drip transfer, and if there is air or aerosol in addition to it, then what is their relative role? These are important issues, and it seems to me that they cannot be ignored, ”says Munster.
Milton plans research using a sophisticated funnel-guided device called the Gesundheit and measures how many drops patients throw into the air when they cough and breathe. These studies will help to dot all the “and” in the issue of aerosol formation and its role in disease transmission.
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