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> It either works or it does not.

You do realize that, in medicine, things "work" on a spectrum right? A pill might be x% effective at alleviating certain systems in particular cases, etc. Why shouldn't the case be the same for masks? There are far more variables than "bool masked = true". What kind of mask material was worn? Was it a well-fitted mask? Was it a particulate filter mask or a simple one? Was the infected person masked? The non-infected? Etc.

the point I was making is that the story, at least in my reading, is being presented primarily as scientific evidence on the effectiveness of masks in school.

Especially the WaPo article. If 50% of students in a classroom get infected after 2 days in school while wearing masks then, IMHO, masks can't be all that effective in the first place.

the whole article tries to suggest that the infections happened during that period she removed the mask ... there is no evidence for that whatsoever

You’re right to question that. From my understanding, she was masked except for the story reading. Teachers need to use facial expression to convey what they’re reading, not just for those with disabilities, hearing problems, etc… but for all children. People who take this as a fable about mask wearing know nothing about pedagogy. It’s a cautionary tale about the need for testing. It also serves to contextualize the precarious trade offs facing our educators and educational system. There are no easy answers; though more testing and vaccinations for the more at risk are obvious takeaways.

> If 50% of students in a classroom get infected after 2 days in school while wearing masks then, IMHO, masks can't be all that effective in the first place.

I believe the primary assertion has always been that making protects others more than it protects oneself. So I wouldn't consider this a contradiction of that. That said, it's entirely possible that the 50% of students who didn't get infected were wearing superior masks. Or, perhaps 80% of the students would have been infected if no one had worn masks.

In short, you can't really draw a meaningful "see masks don't work" conclusion from this.

yes, you are correct to note there is a difference between the confidence of the narrative and what science acftually says you can strongly conclude in a situation like this. This is common in journalism and it's our job to call out statements like these when they are not truly supportable by evidence.

>Where is the evidence that her wearing a mask would have changed the outcomes?

There is multiple studies that show masks are effective at _slowing down_ the spread.

>It either works or it does not.

Huh? This is like saying, "chemotherapy works or it does not."

>Sorry, does not take much to see that, just simply look at everyday observations.

Yep. I'm looking. There's mass deaths a day. Funny the activity is in the anti-mask states, huh?

>yet NONE have exhibited anything close to the 91% infection rates

The CDC said 91% of kids live in high risk places... it has nothing to do with the infection rate. You need to _read_ sources and not just emotionally react.

https://www.cbsnews.com/video/report-91percent-of-students-l...

> There's mass deaths a day. Funny the activity is in the anti-mask states, huh?

I suggest you look at the actual data - no such correlation exists.

The majority of US states have similar death rates per population at around 2K deaths per 1M citizens. (with a spread of around +/- 15%) You can find examples for each,

Death rates correlate much better to wealth and way of living than local policies.

> The majority of US states have similar death rates per population at around 2K deaths per 1M citizens. (with a spread of around +/- 15%)

The range is actually about 40 to 300 per 100K (or 400 to 3000 per million), but what the upthread claim seems to be about is the recent death rate, not the total death rate. No one I can find reports that per capita, but I suspect it has even more variation (California is about middle of the road for total deaths, but was an early leader with its population centers hit really hard at the beginning of the pandemic, while a number of the places in the South that weren't hit hard initially have gotten up near the top in total deaths per capita.)

There are lots of models, but the only study I’m aware of showed that blue surgical masks had ≈10% efficacy when worn correctly, with cloth masks and gaiters less effective.

Additional ventilation seemed to have better efficacy.

The chart I saw showed that masks are somewhat effective for ingress and somewhat effective for egress contamination. When both parties are wearing the mask, and are social distancing, etc, the effectiveness goes up considerably.

The only singular control that works in a vacuum is a vacuum. So unless you are working in a vacuum, you need to stack controls in your favour. Just like you do in every other situation in life.

I've only ever seen them saying problems with school environments amount to a lack of good air circulation with people breathing the same air in and out amongst themselves for hours at a time. That's exactly what the CDC and everyone else has said to avoid doing, and why the phone apps rate 15 minutes of close proximity as enough exposure to warrant a test.

Just like with rubbing alcohol, time and amount have to be taken into account. Water will put out nearly any household fire. But only if other controls accompany it, and there is enough of that water for enough time to have the desired effect.

She took her mask off to read. They were all in that contaminated environment for most of the day. There is every reason to expect infections in such an environment.

The problem is lack of testing and slowness testing. The US I hate to say it, has been shameful in this regard compared to other developed nations. Teachers need to get tested and get results, quickly. That’s just not happening in the US. This case is the inevitable result of that lack of testing. Have you tried to get tested? I have and had to give up and go buy a test at CVS. It cost me 40 dollars and I was lucky they had tests on the shelf and I had time in my busy schedule to do it. Teachers probably have less time, less money, and may think they don’t need a test if they’ve been vaccinated.

$40?! Self-tests were 5 EUR each when they first hit the stores in Germany a few months ago, and are now about 1 EUR each.

The vaccination situation until July was frustrating, though.

> It either works or it doesn't

Oh yeah, because percentages, probabilities, risk mitigation, etc aren't a thing. Everything is either 0% or 100%

But anyway, why aren't teachers at least using N95 masks?

Masks help infected people not spread COVID, they are less useful at preventing uninfected from catching COVID. Everyone has to wear them though because no one knows who has COVID at any given time.

alas, evidence to that efficacy of masks is severely lacking

tell me, why is that 16 months into this pandemic there are no definitive studies to measure the actual effect of masks, you know one with a control and masked people? Yet it is the easiest thing to measure ever.

We can test an actual life saving vaccine (that also carries huge risks while under development) with 40K volunteers but the mask seems to elude the scrutiny.

The CDC should just do the fracking study and put this issue to rest already. Strangely they are not.

We just assume that masks work and therefore leaving a control group unmasked is unethical. It is the same with the vaccines. The trials have technically not finished yet, but the control groups have long been vaccinated. The real control groups now are the much maligned vaccine hesitant.

By "fracking", did you mean "fucking", or did I miss something?

I made this case a couple of weeks ago, and in response to the conversation I set out to do another literature review (which I hadn't done in about a year, and at that time data were sorely lacking).

I was happily surprised to find that several reasonably applicable studies have been published in the meantime, and seem to universally support a statistically significant reduction in infections.

If you're basing your statements on literature review from ~9 months ago, I suggest that you look again, the top results on PubMed were extremely easy to find and virtually all had free public access.

Of the top of my head, relative risk reduction with vs without masks varied between 30-70% depending on the study, with absolute risk reduction more like 10% (with the absolute risk being fairly low to begin with).

I'd be eager to see a proper study (with control groups) and it would go a long way to convince me.

All I have seen so far are studies that relate to case numbers going one way or another when a policy was made or not. Simulations, behaviors etc. Sorry that is just not convincing. Case numbers vary a lot with or without measures. In my opinion when you require masks people don't do certain things as often ... does that mean that the mask protected you?

You are sending me to search PubMed, instead of linking to a paper that operated with a randomized controlled trial. That is the typical answer one gets when asks for an RCT on masks.

The question is: are you actually qualified to judge wwhat is a "proper" study? Like, trained in reading biological study literature (it's not straightforward) or able to identify flaws in trial design?

I think most people aren't qualified to judge.

I understand the concern and is valid - it is like the No True Scotsman fallacy ... is there a "proper study".

yet all I am asking is there an RCT study on masks where they measured actual infection rates on a subpopulation randomly assigned to wear a mask? It is not a particularly unusual design, it is regularly done for vaccines and drugs. Measuring the actual effect on the people that are assigned to each group.

I believe that there is no RCT that would indicate that masks work. I have never seen one. As I said I'd be eager to read it if there was a study like that.

For example the Cohrane review on masks analyzed many studies, none indicated that masks work:

https://www.cochrane.org/CD006207/ARI_do-physical-measures-s...

> Compared with wearing no mask, wearing a mask may make little to no difference in how many people caught a flu-like illness (9 studies; 3507 people); and probably makes no difference in how many people have flu confirmed by a laboratory test (6 studies; 3005 people).

Yet all of a sudden CDC claims masks are super effective.

Let me put my question another way. From what you're writing (I read multiple comments of yours in this post) it doesn't look like you're qualified to judge a paper on its merits. So I have to ask why you're asking for "a proper study", if you're not qualified to judge the study?

I am qualified to judge a scientific paper, but I don't think this should be a personal judgement call of who the "better expert" is. I am trying to avoid calling to authority when deciding an objective truth.

On this topic a reasonably intelligent person reading a reasonably well written scientific paper can understand its strengths and weaknesses. It is not that complicated, we would be talking about simple counts: X people were enrolled, Y people got infected with masks Z people infected without masks. Yes there is statistics involved, there are corrections to be made, proper tests to be chosen, but at end we are talking about a few integer numbers and their relationships. We are not discussing the unsolved mysteries of quantum chromodynamics.

If you look at the information for multiple vaccine papers the data is detailed, granular, compelling and evident - even though I could not design or perform the same analysis myself. There is no debate there that it works.

Yet there is no similarity in the data robustness or even availability when it comes to effectiveness of masks.

I believe that there are no RCT studies on masks that would support their benefits. The Cohran review that I linked on the state of the field also comes to the same conclusion.