- Earlier in the day, the World Health Organization said it contacted the CDC about the guidance change.
- The WHO has said Covid-19 primarily spreads through respiratory droplets that pass when an infected person coughs, sneezes or breathes.
The Centers for Disease Control and Prevention said Monday it erroneously posted guidance saying the coronavirus spreads through airborne particles that can remain suspended in the air and travel beyond 6 feet.
The updated guidance, posted on the CDC's website on Friday, also recommended that people use air purifiers to reduce airborne germs indoors to prevent the disease from spreading, according to Reuters.
"A draft version of proposed changes to these recommendations was posted in error to the agency's official website," the CDC said Monday. "CDC is currently updating its recommendations regarding airborne transmission of SARS-CoV-2 (the virus that causes COVID-19). Once this process has been completed, the update language will be posted."
Earlier in the day, the World Health Organization said it contacted the CDC about the guidance change.
The WHO had not seen any "new evidence" on airborne particles and was checking with the CDC to "better understand" the exact nature of the change, Dr. Mike Ryan, executive director of the WHO's health emergencies program, said during a news conference at the agency's Geneva headquarters.
The WHO has said Covid-19 primarily spreads through respiratory droplets that pass when an infected person coughs, sneezes or breathes. Studies have shown that the coronavirus could spread through aerosols in the air, and the WHO has said it is monitoring "emerging evidence" of possible airborne transmission.
The international agency's position "on this remains the same," Ryan said, "and we've always said going back over months and months about the potential for different kinds of roots of transmission and particularly driven by the context, the proximity, the intensity, the duration and the potential for different forms of transmission."
The update comes days after the CDC reversed controversial coronavirus testing guidance that said people who were exposed to an infected person but weren't showing any symptoms did "not necessarily need a test."
Many public health specialists criticized the CDC's change in testing guidance in August for appearing to play down the significance of testing people who don't have symptoms but who might be spreading the virus.
Studies have suggested the virus can spread through the air. A study published by researchers at the National Institutes of Health earlier this year found that particles of the coronavirus released by talking can remain in the air for eight to 14 minutes.
A study published in the New England Journal of Medicine found that Covid-19 was detectable in aerosols for up to three hours.
In July, the WHO said there is still no "definitive" evidence that indicates the virus is spreading widely by air, although it added that the possibility of airborne transmission in public settings "cannot be ruled out."
If the coronavirus does primarily spread through the air, masks may prove to be more important than ever.
Both health agencies recommend that people wear face masks. Studies suggest the masks may serve as a helpful barrier to spreading infection.
–CNBC's Will Feuer contributed to this report.