4 ms·

> To my knowledge masks are a low cost / lost risk way to reduce the spread, and countries that had faster uptake and higher rates of compliance in mask usage d

by timr 5y ago

> To my knowledge masks are a low cost / lost risk way to reduce the spread, and countries that had faster uptake and higher rates of compliance in mask usage did see lower overall case counts. 1) This isn't really true. There's not a lot of correlation between what nations/states did, and where they ended up. You can find observational papers on both sides of every question (for example, specific to masks, recently: [1]). 2) What else did nations with mask adoption do that could also explain the outcomes? Most places did many things at once, so we're going to be doing post-hoc analysis of this for years. Unfortunately, because nobody thought it appropriate to conduct actual clinical trials, we'll probably never know the answer. There are too many intermingled factors at play so we have to use models, and the modeling work so far has largely been garbage that reflects the assumptions used to create them [2]. (and before anyone says it: yes, it's entirely possible to have conducted clinical trials of masks. A cluster randomized trial, for example, could have been used to establish efficacy early in the pandemic. That we didn't even consider doing these "because it's a pandemic" is one of the biggest scientific lost opportunities of our lifetime.) [1] https://www.medrxiv.org/content/10.1101/2021.05.18.21257385v1.full.pdf https://www.medrxiv.org/content/10.1101/2021.05.18.21257385v... [2] https://www.jclinepi.com/article/S0895-4356(21)00087-1/fulltext https://www.jclinepi.com/article/S0895-4356(21)00087-1/fullt...

Izkata 5y ago
> (and before anyone says it: yes, it's entirely possible to have conducted clinical trials of masks. a cluster randomized trial, for example, could have been used to establish efficacy early in the pandemic. That we didn't even consider doing these "because it's a pandemic" is one of the biggest scientific lost opportunities of our lifetime.) There were studies done; all the way back in March 2020 there was an infographic making the rounds showing a rough estimate of percentage of particles filtered/let through by different types of cloth masks and N95/etc. If I remember right, all the cloth masks let through >50% of particles.
- timr 5y ago
  There have been a number of laboratory studies performed that show varying levels of effectiveness for different kinds of masks and materials (where "effectiveness" is defined in all sorts of different ways that may or may not be relevant). Prior to Covid-19, there was a low-quality evidence base that didn't provide much signal either way: https://www.cebm.net/covid-19/masking-lack-of-evidence-with-politics/ https://www.cebm.net/covid-19/masking-lack-of-evidence-with-... Strapping a mask on a mannequin or to a nozzle is, of course, very different than asking people to wear them everywhere. For evidence of real-world effectiveness of a medical intervention, you do a controlled trial. We could have done some, but we did not. It is notable -- but not at all perfect -- that the only RCT conducted with masks and Covid-19 in 2020 found no significant personal protective effect: https://www.acpjournals.org/doi/10.7326/M20-6817 https://www.acpjournals.org/doi/10.7326/M20-6817 It is a well-done study, and certainly limits the claims that can be made for masks, but doesn't answer every question. A good cluster RCT might have been able to address the question of whether or not masks protect others, for example.
  - mike529 5y ago
    This good cluster RCT is in the midst of being done. https://www.nber.org/papers/w28734 https://www.nber.org/papers/w28734 In this paper they demonstrated an intervention in Bangladesh that increased mask usage by 30 percentage points (from ~10% to ~40%). In the follow-up paper they are doing random antibody testing between the two groups.
  - Izkata 5y ago
    It probably won't be as satisfying for you, but in the US mask-wearing got split along political lines. You can compare red areas (haven't worn masks for months to a year) to blue areas (were still mostly wearing them up to this month when the CDC guidelines changed). Overall, no noticeable effect.
    - bluGill 5y ago
      There are confounders though that make such data not useful (I'm not sure how much statistics can find data in the noise or not though - but it won't be trivial). Red areas are in general more rural and spread out, while blue areas are denser population. Thus blue areas are naturally a different risk level. Also masks and political stance are not a perfect correlation. I personally know democrats who don't wears masks and republicans who do.
kevin_nisbet 5y ago
I'm not sure if I should interpret this as masks are an ineffective tool, or more narrowly that combined with other efforts it's unclear what the impact was since there's a large degree of opinion on the matter compared to data with a higher standard of a peer reviewed double blind study. With masks being such a hot topic in certain regions, it would seem unreasonable to conclude that there is only correlation available. The opinion I'm referring to and cited is in line with this one (just did a quick google search, I don't remember the original source of my assertion): https://www.sciencedaily.com/releases/2020/06/200624082657.htm https://www.sciencedaily.com/releases/2020/06/200624082657.h... There appear to be a number of smaller studies available as well: https://en.wikipedia.org/wiki/Face_masks_during_the_COVID-19_pandemic#Efficacy_studies_for_COVID-19 https://en.wikipedia.org/wiki/Face_masks_during_the_COVID-19... which if cloth masks are effective it would seem to me to be reasonable to extend this to rate of adoption and a contributing factor.
- timr 5y ago
  Note that I've edited my comment to better reflect my thoughts (probably since you wrote this). I don't think you should take this one paper as some kind of definitive rebuttal on masks. You should interpret it as a reasonable summary of current evidence, as well as a not-terrible analysis of US states that poses some serious challenges to the effectiveness of mask mandates. That said, an editorial/letter in science daily is not a rebuttal, and wikipedia is useless for politically sensitive questions. There are many papers on both sides of the issue, and it's easy to cherry-pick a set that support any particular position. Is it the end of the discussion? No. But It's not as cut-and-dried as people make it seem. The evidence base for masks is very low-quality. The issue became political, and as with all things political today, nuance and reason were tossed out the window.
  - flor1s 5y ago
    > Regions with an early interest in face masks had milder COVID-19 epidemics, according to a new letter-to-the-editor published in the American Journal of Respiratory and Critical Care Medicine. (the source of the Science Daily article: https://www.atsjournals.org/doi/pdf/10.1164/rccm.202004-1188LE https://www.atsjournals.org/doi/pdf/10.1164/rccm.202004-1188...) I don't see how this is much less scientific than the non-peer-reviewed paper you posted.
neilwilson 5y ago
Trials on masks universally fail to take into account the field results. And that’s where they fall down. Mask effectiveness relies on purity - everybody doing things with military (or medical) precision. The short of it is that people don’t stick rigidly to the effectiveness requirement. Hence why states and countries that stop compulsion don’t see any deviation in the rate of change. Like HCQ it works in the lab, but not in real life. What’s disturbing is why so many people still believe they do - and why they desperately want them to work - which moves into the political and religious (“I’m pure - it’s everybody else that isn’t”) rather than the scientific. At this stage it’s become like carrying posies to ward off the Black Death.
- deleted 5y ago
  [deleted]

by timr 5y ago

Izkata 5y ago

> (and before anyone says it: yes, it's entirely possible to have conducted clinical trials of masks. a cluster randomized trial, for example, could have been used to establish efficacy early in the pandemic. That we didn't even consider doing these "because it's a pandemic" is one of the biggest scientific lost opportunities of our lifetime.) There were studies done; all the way back in March 2020 there was an infographic making the rounds showing a rough estimate of percentage of particles filtered/let through by different types of cloth masks and N95/etc. If I remember right, all the cloth masks let through >50% of particles.

timr 5y ago
There have been a number of laboratory studies performed that show varying levels of effectiveness for different kinds of masks and materials (where "effectiveness" is defined in all sorts of different ways that may or may not be relevant). Prior to Covid-19, there was a low-quality evidence base that didn't provide much signal either way: https://www.cebm.net/covid-19/masking-lack-of-evidence-with-politics/ https://www.cebm.net/covid-19/masking-lack-of-evidence-with-... Strapping a mask on a mannequin or to a nozzle is, of course, very different than asking people to wear them everywhere. For evidence of real-world effectiveness of a medical intervention, you do a controlled trial. We could have done some, but we did not. It is notable -- but not at all perfect -- that the only RCT conducted with masks and Covid-19 in 2020 found no significant personal protective effect: https://www.acpjournals.org/doi/10.7326/M20-6817 https://www.acpjournals.org/doi/10.7326/M20-6817 It is a well-done study, and certainly limits the claims that can be made for masks, but doesn't answer every question. A good cluster RCT might have been able to address the question of whether or not masks protect others, for example.
- mike529 5y ago
  This good cluster RCT is in the midst of being done. https://www.nber.org/papers/w28734 https://www.nber.org/papers/w28734 In this paper they demonstrated an intervention in Bangladesh that increased mask usage by 30 percentage points (from ~10% to ~40%). In the follow-up paper they are doing random antibody testing between the two groups.
- Izkata 5y ago
  It probably won't be as satisfying for you, but in the US mask-wearing got split along political lines. You can compare red areas (haven't worn masks for months to a year) to blue areas (were still mostly wearing them up to this month when the CDC guidelines changed). Overall, no noticeable effect.
  - bluGill 5y ago
    There are confounders though that make such data not useful (I'm not sure how much statistics can find data in the noise or not though - but it won't be trivial). Red areas are in general more rural and spread out, while blue areas are denser population. Thus blue areas are naturally a different risk level. Also masks and political stance are not a perfect correlation. I personally know democrats who don't wears masks and republicans who do.

kevin_nisbet 5y ago

I'm not sure if I should interpret this as masks are an ineffective tool, or more narrowly that combined with other efforts it's unclear what the impact was since there's a large degree of opinion on the matter compared to data with a higher standard of a peer reviewed double blind study. With masks being such a hot topic in certain regions, it would seem unreasonable to conclude that there is only correlation available. The opinion I'm referring to and cited is in line with this one (just did a quick google search, I don't remember the original source of my assertion): https://www.sciencedaily.com/releases/2020/06/200624082657.htm https://www.sciencedaily.com/releases/2020/06/200624082657.h... There appear to be a number of smaller studies available as well: https://en.wikipedia.org/wiki/Face_masks_during_the_COVID-19_pandemic#Efficacy_studies_for_COVID-19 https://en.wikipedia.org/wiki/Face_masks_during_the_COVID-19... which if cloth masks are effective it would seem to me to be reasonable to extend this to rate of adoption and a contributing factor.

timr 5y ago
Note that I've edited my comment to better reflect my thoughts (probably since you wrote this). I don't think you should take this one paper as some kind of definitive rebuttal on masks. You should interpret it as a reasonable summary of current evidence, as well as a not-terrible analysis of US states that poses some serious challenges to the effectiveness of mask mandates. That said, an editorial/letter in science daily is not a rebuttal, and wikipedia is useless for politically sensitive questions. There are many papers on both sides of the issue, and it's easy to cherry-pick a set that support any particular position. Is it the end of the discussion? No. But It's not as cut-and-dried as people make it seem. The evidence base for masks is very low-quality. The issue became political, and as with all things political today, nuance and reason were tossed out the window.
- flor1s 5y ago
  > Regions with an early interest in face masks had milder COVID-19 epidemics, according to a new letter-to-the-editor published in the American Journal of Respiratory and Critical Care Medicine. (the source of the Science Daily article: https://www.atsjournals.org/doi/pdf/10.1164/rccm.202004-1188LE https://www.atsjournals.org/doi/pdf/10.1164/rccm.202004-1188...) I don't see how this is much less scientific than the non-peer-reviewed paper you posted.

neilwilson 5y ago

Trials on masks universally fail to take into account the field results. And that’s where they fall down. Mask effectiveness relies on purity - everybody doing things with military (or medical) precision. The short of it is that people don’t stick rigidly to the effectiveness requirement. Hence why states and countries that stop compulsion don’t see any deviation in the rate of change. Like HCQ it works in the lab, but not in real life. What’s disturbing is why so many people still believe they do - and why they desperately want them to work - which moves into the political and religious (“I’m pure - it’s everybody else that isn’t”) rather than the scientific. At this stage it’s become like carrying posies to ward off the Black Death.

deleted 5y ago
[deleted]