The Centers for Disease Control and Prevention posted guidance Friday evening saying that aerosol transmission might be one of the "most common" ways the coronavirus is spreading — and then took it down on Monday.

The now-deleted updates were notable because so far the CDC has stopped short of saying that the virus is airborne.

The agency says the guidance was a draft version of proposed changes that were posted in error to its website. The CDC says that it is updating its recommendations regarding airborne transmission of the virus that causes COVID-19 and that it will post updated language once that process is complete.

Over the weekend, the CDC page "How COVID-19 Spreads" included among the most common modes of transmission "respiratory droplets or small particles, such as those in aerosols, produced when an infected person coughs, sneezes, sings, talks, or breathes."

It continued: "These particles can be inhaled into the nose, mouth, airways, and lungs and cause infection. This is thought to be the main way the virus spreads." The guidance also stated that these particles might travel farther than 6 feet.

For a few days, researchers who have suspected aerosol transmission for months cheeredthe update as a long-overdue acknowledgment of accumulating evidence for how the virus transmits, particularly in indoor spaces.

Now the page has reverted to what it said before — that the virus spreads between people in close contact through respiratory droplets. The page makes no mention of aerosol transmission.

NPR's Pien Huang contributed to this report.

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