The U.S. Centers for Disease Control and Prevention updated its guidelines Monday to say coronavirus can spread from airborne transmission over a distance greater than six feet, and from exposure to tiny droplets and particles known as aerosols that can remain in the air for minutes or even hours, after deleting a similar notice last month, saying a draft was posted in error.
The CDC website says there is now evidence people with Covid-19 have infected people who were more than 6 feet away and that airborne transmission has occurred in enclosed spaces with inadequate ventilation.
Scientists believe the number of infectious droplets or particles produced by someone with Covid-19 become concentrated enough to spread the virus to people in the room at the same time or “shortly after,” according to the CDC.
Similarly, the CDC guidance deleted last month said there was “growing evidence” aerosols could travel more than 6 feet and infect someone.
At the time, CDC officials told the Washington Post it was removed because it had not been reviewed yet and there was concern people would think airborne transmission is the primary way the virus spreads.
The CDC previously said the virus was transmitted through large respiratory droplets, often emitted from coughing or sneezing, at close range.
In July, 239 scientists urged doctors and public health entities such as the World Health Organization and CDC to recognize that coronavirus can spread through airborne transmission. They said studies conducted by the signees and additional scientists demonstrated “beyond any reasonable doubt” that the virus can spread from microdroplets released when an infected person exhales, talks or coughs. The scientists noted airborne transmission poses an additional risk in poorly ventilated rooms. The World Health Organization publicly recognized airborne transmission in July.