On Wednesday, March 25, 2020, there is a sign on Marina Boulevard in Marina Green in San Francisco, California, USA, asking people to stay 6 feet apart.
David Paul Morris | Bloomberg | Getty Images
The Centers for Disease Control and Prevention said Monday they falsely published guidelines stating that the coronavirus spreads through airborne particles that are suspended in the air and can move past 6 feet.
The updated guidelines posted on the CDC website on Friday also recommended using air purifiers to reduce indoor airborne germs and prevent the disease from spreading, according to Reuters.
"A draft of the proposed changes to these recommendations was incorrectly posted on the agency's official website," the CDC said Monday. "CDC is currently updating its recommendations for airborne transmission of SARS-CoV-2 (the virus that causes COVID-19). Once this process is complete, the update language will be released."
Earlier in the day, the World Health Organization said it had contacted the CDC about the change in guidelines.
The WHO did not see any "new evidence" of airborne particles and had checked with the CDC to "better understand" the exact nature of the change, said Dr. Mike Ryan, Executive Director of the WHO Health Emergencies Program, during a press conference at the agency's headquarters in Geneva.
The WHO has said that Covid-19 spreads mainly through respiratory droplets that pass when an infected person coughs, sneezes or breathes. Studies have shown that aerosols can spread the coronavirus in the air, and the WHO has stated that it is monitoring "emerging evidence" of possible airborne transmission.
The position of the international agency "remains the same in this regard," said Ryan, "and we have said time and again that for months we have pondered the potential for different types of transmission roots, particularly driven by context, proximity and intensity the duration and the potential for different forms of transmission. "
The update comes days after the CDC rolled back the controversial coronavirus testing guidelines that said people who were exposed to an infected person but showed no symptoms "didn't necessarily need a test".
Many public health professionals criticized the CDC's August change to testing guidelines for appearing to downplay the importance of testing people who have no symptoms but who may be spreading the virus.
Studies have shown that the virus can spread through the air. A study published earlier this year by researchers at the National Institutes of Health found that particles of the coronavirus released by speaking can stay 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 announced that there was still no "definitive" evidence that the virus was spreading widely by air, although the possibility of airborne transmission in public facilities "cannot be excluded".
With the coronavirus primarily airborne, masks may be more important than ever.
Both health authorities recommend wearing face masks. Studies suggest that the masks can act as a helpful barrier to the spread of infection.
–CNBC's Will Feuer contributed to this report.