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Small-Scale Question Sunday for December 31, 2023

Do you have a dumb question that you're kind of embarrassed to ask in the main thread? Is there something you're just not sure about?

This is your opportunity to ask questions. No question too simple or too silly.

Culture war topics are accepted, and proposals for a better intro post are appreciated.

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I thought it was shown that they don't do much, especially outside. And they mostly protect others from you. They don't prevent you from getting infected.

These days there's no reason to be wearing low-quality masks, which were common in 2020 when there were shortages of medical-quality masks. N95 or equivalent masks are now cheap and plentiful. And much more comfortable than cloth masks. Also, I know multiple people who have better than N95 respirators (P100, I think?), mainly for plane trips, I think, which are likely plenty good for protection from someone unmasked and infected. While most of my friends have gotten COVID at least once by now, I've never heard of anyone who thought they acquired it while wearing a mask, including multiple stories of groups of people getting COVID and the people with them wearing masks did not.

There is no better evidence that N95 masks offer more protection than KN95 masks, surgical, or cloth masks, against respiratory illnesses. And the more pervasive evidence about surgical and cloth masks is there is no good evidence they reduce the spread of respiratory illnesses. And sadly, few of the studies on mask usage even bothered to collect any data whatsoever on possible harm from frequent mask wearing.

That's the study I was referencing that shows that telling people to wear masks doesn't seem to do a lot. It's really hard to do a study on whether consistent mask use works because virtually everyone falls into one of two groups:

  1. Won't mask consistently.
  2. Will mask consistently anyway.

And furthermore, there's social desirability bias on telling a researcher studying masking that you're in group (2) if they are having you wear masks for a study.

One study included in the Cochrane review (well, the data at least) addressed the difference between 1000+ medical professions treating covid-19 patients randomly selected into surgical and n95 masks and it didn't find a statistically significant difference between the groups. This design significantly reduces the danger of the social desirability bias effect you're talking about, but still relied on self-report for adherence to the assigned mask-type and wearing consistency, however randomization should reduce that effect, too. There were 4 others with similar results in different settings (1 found weak effect).

So perhaps you believe that the available evidence doesn't adequately account for the the issue of self-report when comparing mask vs no mask, but then why do you also believe N95 masks are better than surgical masks when there is either no or very weak evidence it makes a difference?

If your belief about how viruses mechanistically transmit between humans is true and the N95 directly addresses this concern to a much higher degree than surgical or cloth masks, why wouldn't we see stronger evidence of a difference when in people testing positive with influenza-like-illness?

It's intuitive that masks do something, but they also have other effects which could wash out the possible reduction in the mechanistic transmission you discussed above in another comment.

why do you also believe N95 masks are better than surgical masks when there is either no or very weak evidence it makes a difference?

I have not carefully reviewed the literature myself. I'm following what expert science communicators claim the literature says, as I expect them to be better identifying the flaws in studies and understanding what they actually say.

I agree that study result you linked is surprising. I guess it implies that either the masks are equivalent in quality in this setting or that masking had no measurable effect, most likely due to transmission at work being a rounding error compared to community transmission. Or something else is going on that I don't know to look for.

especially outside.

Wait, what? Do people wear them outdoors? Seriously? That's just so incredibly stupid and something that I almost never saw here in Finland even during the worst peaks.

All the fucking time. On a bike, scooter, walking through very low density suburbs, hiking. By themselves in their car.

Yes, about 20% of people wore masks outdoors here.

I do see it. Presumably either because it's cold outside and a mask keeps your face warm or because they're not going to be outside for very long and it's not bothering them enough to take it off and put it back on (possibly exacerbated for some people by getting the mask properly adjusted to a good fit taking time, so not worth the trouble to have it off for just a few minutes).

It is in fact possible, albeit very unlikely to transmit COVID outdoors. Depending on how paranoid / medically fragile someone is, and how annoying they find wearing a mask, some people may consider it worth it to wear a mask outdoors for health reasons, at least when close to other people. I only know one person who does that, but they also use more serious respirators than just an N95 mask.

Where I am, in the northeast US, yeah, there are still a good number of outdoor maskers.

Right, so people who think they might be sick can play it safe before going on a plane or whatever.

This is probably the time of year when it’s most likely to have a positive effect. It’s the Venn diagram of “most time indoors” and “most determined to push through and go to events anyway.”