A fundamental change to COVID-19 guidance that was posted unannounced by the Centers for Disease Control and Prevention last week was abruptly disappeared at midday Monday. Curiously, the top health body didn’t issue an announcement about the initial changes. In an update to its website over the weekend, the CDC had confirmed what has long been suspected and announced by other countries’ health agencies—that the virus spreads mainly through the air via respiratory droplets that are expelled by people when they talk, breathe, cough, sneeze, or sing. As of Monday morning, the site read: “There is growing evidence that droplets and airborne particles can remain suspended in the air and be breathed in by others, and travel distances beyond six feet (for example, during choir practice, in restaurants, or in fitness classes).”

However, that language was gone by noon on Monday. A source inside the CDC told The Daily Beast that guidance was posted by accident Friday and that the information had yet to go through an internal review by the agency’s scientists. The site now states: “A draft version of proposed changes to these recommendations was posted in error to the agency’s official website. 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.” The CDC has long resisted the idea that the virus spreads any further than six feet through the air. The guidance listed early Monday had directed people to “stay at least six feet away from others, whenever possible,” where it previously suggested maintaining “good social distance” of about six feet.