After a group of more than 200 scientists published and signed a letter urging the agency to update its guidance on virus the illness passes between people, the World Health Organization is now confirming that there is “emerging evidence” of airborne transmission of the coronavirus. 

Dr. Benedetta Allegranzi, the WHO’s technical lead for the pandemic, said during a briefing Tuesday that there was emerging evidence of airborne transmission of the virus but noted it was not definitive. 

"We acknowledge that there is emerging evidence in this field, as in all other fields regarding the Covid-19 virus and pandemic and therefore we believe that we have to be open to this evidence and understand its implications regarding the modes of transmission and also regarding the precautions that need to be taken," Alleganzi said.

“The possibility of airborne transmission in public settings — especially in very specific conditions, crowded, closed, poorly ventilated settings that have been described — cannot be ruled out,” she continued.

“However, the evidence needs to be gathered and interpreted, and we continue to support this.”

Maria Van Kerkhove, the WHO’s technical lead on the pandemic, said the agency would soon be publishing a scientific brief summarizing all the information they currently have on modes of transmission. “We have been talking about the possibility of airborne transmission and aerosol transmission as one of the modes of transmission of Covid-19, as well as droplet. We've looked at fomites. We've looked at fecal oral. We've looked at mother to child. We've looked at animal to human, of course as well," Van Kerkove said.

On Tuesday, the Trump administration formally withdrew the United States from the WHO.