The Centers for Disease Control and Prevention has now updated its website on COVID-19 transmission to acknowledge there are “limited, uncommon circumstances” where airborne transmission occurred between people over 6 feet apart or after an infected person left an area. The agency’s How COVID-19 Spreads page now includes a bold subheading that states the coronavirus can “sometimes be spread” through airborne transmission. Previously, the CDC did not acknowledge that airborne transmission was a significant means of viral spread, which other countries’ health agencies have already done. A resource page also reaffirms SARS-CoV-2 can be transmitted under “special circumstances,” including enclosed spaces, prolonged exposure to respiratory particles generated by shouting, singing, exercising, and poor air circulation. The CDC now also explicitly notes that the virus can infect people who are over six feet away from each or after an infected person has left a particular area.

“There is evidence that under certain conditions, people with COVID-19 seem to have infected others who were more than 6 feet away,” the section now reads. “These transmissions occurred within enclosed spaces that had inadequate ventilation.”