KEY POINTS
  • White House coronavirus advisor Dr. Anthony Fauci said on Monday that he thinks "there certainly is a degree of aerosolization" causing the coronavirus to spread, although the topic is still being studied. 
  • In July, the WHO published new guidance that acknowledged it can't rule out the possibility the coronavirus can be transmitted through air particles in closed spaces indoors, including in gyms and restaurants.
  • Fauci said it has become "much clearer" that someone is likely at greater risk if they're in an indoor space where there's less air circulation and "any degree of aerosolization."

White House coronavirus advisor Dr. Anthony Fauci said on Monday that he thinks there is "a degree" of airborne spread of the coronavirus, although the role it plays is still being studied. 

"I think that there certainly is a degree of aerosolization," Fauci, director of the National Institute of Allergy and Infectious Diseases, said during an interview with the Journal of the American Medical Association. "But I'm going to take a step back and make sure that we learn the facts before we start talking about it." 

Health experts have said that the coronavirus is generally transmitted person to person through large respiratory droplets, often when someone sneezes or coughs. The World Health Organization first warned in March that such droplets could be kicked up into the air where they might become airborne and linger in certain environments. 

In July, the WHO published new guidance that acknowledged it can't rule out the possibility the coronavirus can be transmitted through air particles in closed spaces indoors, including in gyms and restaurants. They previously had warned that the virus may become airborne in certain environments, such as during "medical procedures that generate aerosols."

The WHO acknowledged in its guidance that transmission in those environments could also have occurred through droplets and from surfaces.

Fauci, during the interview with JAMA, said it has become "much clearer" that someone is likely at greater risk if they're in an indoor space where there's less air circulation and "any degree of aerosolization." Some experts who have studied aerosolization have indicated there are larger particles discharged when someone coughs or sneezes that might float in the air longer than previously thought, he said. 

"We need to pay a little bit more attention now to the recirculation of air indoors, which tells you that mask-wearing indoors when you're in a situation like that is something that is as important as wearing masks when you're outside dealing with individuals who you don't know where they came from or who they are," Fauci said. 

"It's something we're learning more and more about. We've got to make sure that we're humble enough to accumulate new knowledge and use it as we get it," he added.

Some scientists across the globe have previously urged the WHO and other health agencies to give more weight to the role of the airborne spread of Covid-19, calling for them to update their guidance. 

— CNBC's Will Feuer contributed to this report.