The CDC started lying about the effectiveness of masks to convince people to stop using them so service workers would have access to them as political pressure on them mounted.
That’s the common explanation given, but from my understanding at least it’s (at least partially) incorrect and the original recommendations were due in part to not understanding Covid was airborne. And that was because of a major communication error ~60 years ago from “Alexander Langmuir, the influential chief epidemiologist of the newly established CDC” who had pressed back on airborne viruses being common as he thought they were too similar to miasma theory.
Like his peers, Langmuir had been brought up in the Gospel of Personal Cleanliness, an obsession that made handwashing the bedrock of US public health policy. He seemed to view Wells’ ideas about airborne transmission as retrograde, seeing in them a slide back toward an ancient, irrational terror of bad air—the “miasma theory” that had prevailed for centuries. Langmuir dismissed them as little more than “interesting theoretical points.”
Langmuir seems to have finally accepted it after a period of time, but the focus was on <5 micron particles and that got snatched out of context and only particles smaller than that being airborne became the medical gospel.
That’s the common explanation given, but from my understanding at least it’s (at least partially) incorrect and the original recommendations were due in part to not understanding Covid was airborne. And that was because of a major communication error ~60 years ago from “Alexander Langmuir, the influential chief epidemiologist of the newly established CDC” who had pressed back on airborne viruses being common as he thought they were too similar to miasma theory.
Langmuir seems to have finally accepted it after a period of time, but the focus was on <5 micron particles and that got snatched out of context and only particles smaller than that being airborne became the medical gospel.
At least, if this wired article about the scientists who tried to convince the WHO that Covid was airborne is accurate
Here’s a LW discussion thread of this article from back then, including a review comment I made with some extra info which I think still holds up well.