Sunday, January 29, 2023

Preliminary research suggests the COVID-19 virus loses 90 percent of its infectivity after 20 minutes in the air

A new pre-print study has offered some preliminary evidence suggesting that the virus that causes COVID-19 loses most of its infectivity after 20 minutes in the air.

A not yet peer-reviewed study outside the United Kingdom measured the stability of SARS-CoV-2 in aerosol droplets between five seconds and 20 minutes.

After 20 minutes, the researchers say the infectivity of SARS-CoV-2 dropped to about 10 percent from where it started, with a large portion of that damage occurring within the first five minutes of being aerosolized.

The article is a pre-print and has not been peer-reviewed, which means it has not been evaluated by the medical community for any potential errors or inaccuracies.

The researchers say the data suggests that dry air may help limit the overall exposure to SARS-CoV-2, although further confirmation is needed as well as a possible effect of pH and CO2 levels. Research is required.

The study also based most of its measurements on versions of SARS-CoV-2 that were isolated early in the pandemic, including alpha. However, no significant difference was found between the three variants used.

“While the current consensus is that the half-life of SARS-CoV-2 in the aerosol phase is between 1–2 hours, if not longer, we report an initial rapid decline in infectivity within seconds to minutes after aerosol generation. do,” the study authors write.

“Under all the conditions measured, most SARS-CoV-2 is inactivated within 10 minutes of aerosolization. Further research is needed to determine how long the remaining fraction persists and how it responds to the viral load in the aerosol.” How can it depend?

The transmission of droplets containing SARS-CoV-2 has led to ongoing discussions about ventilation, masking and social distancing, with reports varying how long the virus can remain aerosolized or suspended in the air.

How long SARS-CoV-2 can survive has been investigated since the early days of the pandemic.

The Public Health Agency of Canada says that SARS-CoV-2 is transmitted from one infected person to another through respiratory droplets, which can range in size from large droplets falling on the ground in seconds or minutes to small droplets. are sometimes called aerosols, which freeze. In the air especially indoors.

Information published in May 2020 by UK Research and Innovation states that SARS-CoV-2, like many respiratory viruses, is spread between most people through small droplets released from the nose or mouth of an infected person.

At the time it was said that the half-life, or the time it took for 50 percent of the virus to become no longer infectious, was just over an hour in droplet aerosols, with some surviving for three hours or more.

By the spring of 2021, scientists and doctors had increasingly come to the conclusion that aerosols are the primary mode of transmission of SARS-CoV-2.

The latest UK study used a technique called CELEBS, or Controlled Electrodynamic Levitation on a Substrate and Extraction of Bioaerosols, which involves suspending virus-containing particles under controlled conditions. The particles are subsequently plated on a cell culture.

The researchers found that the infectivity of SARS-CoV-2 dropped to an average of 54 percent at low relative humidity, or 40 percent, almost immediately within five seconds.

This was followed by a period of relative stability, which decreased to an average of 19 percent after five minutes.

Under high relative humidity conditions of 90 percent, infectivity gradually dropped to 48 percent after aerosolization within the first five minutes.

In both scenarios, infectivity appeared to plateau after 10 min before reaching the same points by the 20 min mark.

Researchers say the data are consistent with the view that the virus spreads mainly over short distances.

“The rapid loss of infectivity demonstrated in these measurements provides an alternative explanation for a short transmission distance, with rapid airborne loss of viral infectivity decreasing the likelihood of transmission as the distance from the particle source increases, even if Virus particles are small and capable of traveling long distances,” the study says.

On CO2, the researchers say the elevated levels are a sign that a place is densely packed and poorly ventilated, possibly creating conditions where SARS-CoV-2 is more stable in the air. They suggest that CO2 monitors may be valuable in assessing exposure relative to the indoor environment.


Nation World News Desk
Nation World News Desk
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