Mass-reach posts came later, but sooner than the US mainstream updates
https://www.lesswrong.com/posts/h4vWsBBjASgiQ2pn6/credibility-of-the-cdc-on-sars-cov-2https://slatestarcodex.com/2020/03/23/face-masks-much-more-than-you-wanted-to-know/
Mass-reach posts came later, but sooner than the US mainstream updates
https://www.lesswrong.com/posts/h4vWsBBjASgiQ2pn6/credibility-of-the-cdc-on-sars-cov-2
https://slatestarcodex.com/2020/03/23/face-masks-much-more-than-you-wanted-to-know/