Story at a glance

  • New research found that after COVID-19 becomes airborne, the virus loses infectivity by 50 to 60 percent within seconds.
  • By the first two minutes, the infectivity rate of COVID-19 dropped further by 90 percent.
  • The new research was published out of the U.K. and has yet to be peer-reviewed.

New research from the U.K. is challenging perceptions of how the coronavirus travels and infects people, with researchers saying COVID-19's infectivity rate begins dropping minutes after virus is released into the air. 

 

In a study uploaded to a preprint server this week, but is yet to be peer-reviewed, researchers in the U.K. found that the airborne infectivity rate of COVID-19 declines over the first 20 minutes after it's been released into the air. The research emphasizes that physical distancing and wearing masks are the strongest tools to prevent a COVID-19 infection. 

Researchers studied the infectivity rate of COVID-19 over the course of 20 minutes and found a decrease almost immediately, with the virus losing infectivity by 50 to 60 percent within seconds of being released into the air and by the first two minutes the infectivity dropped further by 90 percent. After 10 minutes, only 10 percent of the virus remained infectious.  

“It means that if I’m meeting friends for lunch in a pub today, the primary [risk] is likely to be me transmitting it to my friends, or my friends transmitting it to me, rather than it being transmitted from someone on the other side of the room,” said Jonathan Reid, a professor at the University of Bristol and the study’s lead author, to The Guardian 


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The loss of infectivity of COVID-19 has to do with the elevation in pH in virus droplets, with researchers suggesting that as the viral particles leave the moist and carbon dioxide-rich lungs of humans, they begin to rapidly lose water and dry out once they hit the air outside our lungs. That transition to lower levels of carbon dioxide is associated with an increase in pH. 

Researchers said the temperature of the air didn’t make any difference in how infectious the virus was, which contradicts previous theories that COVID-19 doesn’t spread as easily in higher temperatures. 

However, researchers did say that airborne droplets are notoriously difficult to study, as the vast majority of indoor aerosols originate from candles, dust, outdoor air, pollution and food cookers. However, under most conditions, exhaled aerosol droplets rapidly lose both moisture and heat through evaporation.   

Researchers only studied three COVID-19 variants, which included the alpha variant. They hope to continue experiments that look at the infectivity rate of the omicron variant in the coming weeks. 


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Published on Jan 11, 2022