Agree & upvoted; this needs to be better understood. Especially noteworthy is the section you linked to is written for health-care workers, and they’re confirming that a homemade mask is better than nothing (while also recommending the homemade mask dead last.)

Unfortuately, the CDC really is giving out conflicting guidance here. For example, higher up in the section for lay-people is this: “You do not need to wear a facemask unless you are caring for someone who is sick (and they are not able to wear a facemask). Facemasks may be in short supply and they should be saved for caregivers.” https://www.cdc.gov/coronavirus/2019-ncov/prepare/prevention... (In “How to Prepare | Protect Yourself”)

I don't see a contradiction. The CDC is trying to maximize public health benefit. They recommend stronger protection for people with more exposure to higher levels of the virus. Coincidentally, the people with higher levels of exposure also happen to be health care workers, who need the best available protection to save lives

If you are not exposed to high levels and are not required to put yourself at risk to care for patients, you are at low risk. You can protect yourself with milder measures like social distancing and face protection that is not as effective but not in such short supply

Maybe I misread your intent. I thought you were mostly pointing out the section titled “When No Facemasks Are Available, Options Include”, which would mean we’re talking about something that is not in short supply. I thought you were pointing out that, among other things, the CDC is saying that home-made masks are better than nothing, even for health care professionals, and even if it’s a last resort.

I mean I agree, of course, that they’re trying to maximize public health benefit, I just don’t think the guidance is at all clear to the public. The idea that anything less than N95 is useless is pervasive, you can see it right here on HN. My parents and co-workers believe it because it’s been reported in the mass media in the last weeks: “the CDC said masks don’t protect you!”.

For people who need to work or shop in public places, any kind of masks at all might well be statistically significant alternatives for people who are unable to practice social distancing. China seems to be doing it effectively right now; people are required to wear masks to go to work. They’re not telling the public to avoid masks because doctors need them, they’re telling the public not to leave the house and not to enter a work building without something over your face. It seems like the CDC is saying the opposite, you should not wear a mask unless you’re a doctor. If a bandana is even 50% or 30% or even 5% effective, and they want to maximize public health benefit, why aren’t they recommending people start with what they have at home for times when public exposure is necessary? Seems like that would both increase public health and deflect demand for surgical masks & N95 masks at the same time, no?