CDC issues new guidance on COVID-19, then retracts it. What that means for efforts to contain the virus

The Centers for Disease Control and Prevention quietly changed its coronavirus guidelines over the weekend — and then quietly changed them back today.

On Friday, the agency revamped its guidelines to say the virus spreads mainly through the air when people speak or sing, and that those tiny aerosols can remain suspended and then inhaled. That means indoor gatherings are especially dangerous if the air isn’t filtered and circulated out.

Previously, there was no mention of aerosols. The CDC said the virus spreads mainly between people within six feet of each other through respiratory droplets that fall quickly to the ground. Today, it went back to this position, pulling the updated language and saying the draft version was posted in error.

I like this side-by-side comparison of updated CDC guidance showing the evolution in understanding & clarity (from June 16 --> Sept. 18). Direct link: https://t.co/e4wYXCLBp2

@kprather88 below for single-image clarity) https://t.co/JBUxQiWv5Dpic.twitter.com/K6kuUqHQc2 — Alex Huffman (@HuffmanLabDU)

September 20, 2020

“My concern is that it erodes the public's trust in science, and that's not good for anybody,” says Kimberly Prather, a professor of atmospheric chemistry at UC San Diego and director of the National Science Foundation’s Center for Aerosol Impacts on Chemistry of the Environment.

She was excited to see the updated guidelines on the CDC’s website, and hopes the agency polishes the wording and puts them back. She says it will help schools and other businesses make a plan to reopen.

“A lot of places are restricted in what they can do, because they have to rely on the CDC guidance,” she says. “This document was the best hope I've seen in a very long time because it was giving people the information they needed to move forward in a positive way.”