COVID loses 90% of its contagion capacity 20 minutes after becoming airborne: New Study

The COVID-19 virus loses at least 90% of its virulence within 20 minutes after it is airborne, said a new study conducted by the University of Bristol Aerosol Research Centre. In the first-of-its-kind study, the data sheds light on how the novel virus behaves after it is released in the air during exhalation. The study is currently due for peer review.

The study comes as the world is facing, what health experts claim to be the 'third-wave' of infections from the COVID-19 virus. On Thursday, the global infections crossed 320,988,304 cases with 5.5 million COVID-related fatalities. Since it's inception in late 2019, the virus has reemerged with two new impactful variants - Delta and Omicron - with the latter more contagious than the previous one. Nevertheless, the Omicron variant, compared to Delta, is said to be less severe. The study, overseen by Director of University of Bristol Professor Jonathan Reid, also added that the Coronavirus loses at least 50% of its ability to infect about 10 seconds after it becomes airborne in a typical office environment.

"People have been focused on poorly ventilated spaces and thinking about airborne transmission over meters or across a room," Professor Reid told The Guardian after the study was first reported on Tuesday.

"I am not saying that doesn't happen, but I think still, the greatest risk of exposure is when you are close to someone. When you move further away, not only is the aerosol diluted down, there are also less infections by this because the viruses lost infectivity (as a result of time)," he added.

50% infectivity lost within 10 second

According to the study, when the virus leaves the lung during exhalation, they quickly lose water, leading to a rapid increase in pH as the particles transition to lower levels of carbon dioxide. These factors hinder the virus' ability to infect others. However, the nullification of the virulence is also dependent on the humidity of the surrounding air. With lower than 50% humidity, the virus loses its infectivity within 5 to 10 seconds, the Guardian reported.

“The rapid loss of infectivity demonstrated in these measurements provides an alternative explanation for a short transmission distance, with rapid airborne losses of viral infectivity making transmission decreasingly likely as the distance from the particle source, is increased, even if the particles that contain the virus are small and able to travel long distances,” the study explained.

At 90% humidity, the virus loses its infectivity at a slower pace when 52% of the particles remain active even after 5 minutes. Referring to the data, the study noted that physical distance and masking is the best way to avoid the virus and clarified that ventilation is deemed to be less effective. Although, the overall surrounding temperature has no direct impact on the virus' infecting capacity.

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