[timr]

> Be careful what you are arguing that these trials show: whether masks, when worn properly, work, or whether mask mandates work.

The RCTs have been for masks themselves, not for mandates (this gets a little complicated because of compliance and intention-to-treat analysis, but it's basically true; the researchers were testing masks themselves, not rules surrounding masks). If the masks don't have strong evidence, I don't expect mandates to make the situation better.

[dkonofalski]

Where are you getting this idea that they don't have strong evidence? We have several studies now, in schools, cities, states, and other places, that have shown that, while not perfect, masks have a very noticeable positive effect on reducing transmission and spread.

[timr]

I don't think you're operating in good faith, but since you asked, other people might find this useful. You'll also note that none of the links I am providing here are from Vinay Prasad, since you are convinced he is some kind of astroturfing organization...

There have been exactly two RCTs for masks and Covid during the pandemic, neither of which has shown a large effect [1][2]. The DANMASK study showed no significant PPE effect, and the Bangladesh RCT showed a total effect size of around 0.09% (or a difference of 20 infections on base of thousands). Prior to the pandemic, RCTs for masks and respiratory disease showed weak effects, at best. Cochrane did a review of the literature [3], and found:

> Seven studies took place in the community, and two studies in healthcare workers. Compared with wearing no [surgical] mask, wearing a [surgical] 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).

> We are uncertain whether wearing masks or N95/P2 respirators helps to slow the spread of respiratory viruses.

There have been many uncontrolled studies published. These are useless. Uncontrolled studies are not science (the Missouri study discussed in the OP is not a controlled study, btw).

There have been many laboratory studies published. These are suggestive, but just like a lab study for a drug, not meaningful in the real world without real-world evidence.

[1] https://www.acpjournals.org/doi/10.7326/m20-6817

[2] https://www.poverty-action.org/sites/default/files/publicati...

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

[manicdee]

The Danish study is self reported with no policing of wearing a mask correctly at appropriate times and always using clean masks (not reusing masks from day to day).

> Inconclusive results, missing data, variable adherence, patient-reported findings on home tests, no blinding, and no assessment of whether masks could decrease disease transmission from mask wearers to others.

The Bangladesh study found masks were effective.

The third is a literature review with no indication of quality control, so basically as reliable as the Danish study (no policing of actual mask wearing, no policing of proper mask wearing, no policing of mask hygiene).

[timr]

> The Danish study is self reported with no policing of wearing a mask correctly at appropriate times and always using clean masks (not reusing masks from day to day).

So was the Bangladesh study. They did some surveys to estimate the rate of compliance, but it's not like there was a mask policeman following the participants around.

If only you folks would spend half as much effort reading the studies you prefer as you do the ones you dislike, you might be more credible.

> The Bangladesh study found masks were effective.

The Bangledesh study found a grand total of 20 infections separating the two arms of the surgical mask study. Out of thousands. A total effect size of 0.09%. It found that cloth masks had no significant effect.

Also, my favorite: It found that one color of cloth mask was significantly different than the other one. We all know that viruses have a strong red/blue preference, right?

Maybe we should be a little circumspect about what "significance" means here.

[manicdee]

I am not sure why you are attributing motive to me when I am simply pointing out the flaws in an anti-masker’s supposed supporting evidence.