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From Martin Kulldorff, esteemed (though contrarian) Harvard Med epidemiologist: "Odd that mask advocates are excited by this study. As a vaccine advocate, I wo

From Martin Kulldorff, esteemed (though contrarian) Harvard Med epidemiologist: "Odd that mask advocates are excited by this study. As a vaccine advocate, I would be horrified if a vaccine trial showed 11% efficacy. Based on the 95% confidence intervals, we do not even know if surgical mask efficacy is more than 0%." https://twitter.com/MartinKulldorff/status/1433202651106201607?s=20 https://twitter.com/MartinKulldorff/status/14332026511062016...

SubiculumCode 5y ago
I think this thread is a decent refutation that the CI lower bound was at 0: "First, the 11% reduction comes from a 30% increase in mask-use. The IV estimate (naively scaling things linearly) would thus be more like a 37% reduction in COVID from going from zero to universal masking." "Second, we find much larger effects among the elderly (a 35% reduction among 60+ without the above scaling). This suggests that the total reduction in morbidity and mortality from universal masking may be considerably larger than even the 37% number, perhaps more than 50%." "Third, it's not quite an apples to apples comparison because we are estimating the community impact of masks, whereas the vaccine studies only isolate the individual protective effect. The efficacy of vaccines at the population level may be larger than trials imply." https://twitter.com/Jabaluck/status/1433129444940599296 https://twitter.com/Jabaluck/status/1433129444940599296
dragontamer 5y ago
EDIT: Woops, read wrong. Lemme post the quote instead. > The observers found that just over 13% of people in the villages that received no interventions wore a mask properly, compared with more than 42% of people in the villages where each household received free masks and in-person reminders to wear them So an increase of 13% masking to 42% masking led to an 11% effective drop in COVID19 spread. So even though 70% of people weren't affected (either the 13% who wore a mask anyway, or the 60% of people who ignored the mask advice), you still had a measurable decrease in COVID19 spread. Which means masking mandates / masking propaganda works. Even with the huge number of people who ignore it, its still an effective means to cut down on COVID19 spread.
slg 5y ago
Except that was not what was tested. Here is what they did: >No-cost free masks distribution - One-third of the intervention villages received a cloth mask and two-thirds of the intervention villages received a surgical mask[5] during household distribution and distribution at marketplaces and other public locations weekly or every fortnight. Masks were also distributed at mosques on three Fridays during the first four weeks of the intervention. >Offering information on mask-wearing - Along with the distribution, the research team showed a brief video of notable public figures discussing why, how, and when to wear a mask. The video featured the Honorable Prime Minister of Bangladesh Sheikh Hasina, the head of the national Imam Training Academy, and the national cricket star Shakib Al Hasan. During the distribution visit, households also received a brochure based on WHO materials depicting proper mask wearing. >Reinforcement in-person and in public - In an effort to create a social norm, mask promoters encouraged non-mask wearers to wear a mask, providing a mask if the individual did not have one. Mask promoters also played public service announcements in public areas using handheld microphones. >Modeling and endorsement by trusted leaders. - Religious leaders (imams) discussed the importance of mask-wearing at Friday prayers from a scripted speech provided by the research team. This is a test of the effectiveness of these public policies and not the effectiveness of masks in general.
- kragen 5y ago
  Hmm, are you suggesting that those public policies might have had an impact on covid transmission that wasn't mediated through mask-wearing? For example, having the imams discuss the importance of mask-wearing might discourage people from going to Friday prayers? That seems unlikely but conceivable.
  - Volundr 5y ago
    Not really. What's being suggested is that what's being tested is both societal compliance combined with mask effectiveness. To dramatically over simplify, let's assume we have a population of 10, none of them mask wearers. Let's also assume masks are 100% effective at preventing Covid infection. These measures convince only 1 person to wear a mask. In the control group (no advocacy) 10/10 are infected. In the study group 9/10 are because that one person wore a mask. So we've got an effectiveness of 10%, despite masks in our contrived example being 100% effective. The effectiveness is blunted by lack of compliance.
input_sh 5y ago
And then see this response to that claim by one of the study's authors: https://mobile.twitter.com/Jabaluck/status/1433129444940599296 https://mobile.twitter.com/Jabaluck/status/14331294449405992...
- barbazoo 5y ago
  which seems to have been deleted in the meantime
- kragen 5y ago
  Better link: https://birdsite.xanny.family/Jabaluck/status/1433129444940599296 https://birdsite.xanny.family/Jabaluck/status/14331294449405...
  - input_sh 5y ago
    I wouldn't really call it better if it doesn't have a proper certificate.
weaksauce 5y ago
because compliance was voluntary... the study merely had leaders in the community wear masks and provided free masks to those that wanted them plus education and reminders; it wasn't a compulsory thing so this is mainly a lower bound on effectiveness. > Providing free masks, informing people about the importance of covering both the mouth and nose, reminding people in-person when they were unmasked in public, and role-modeling by community leaders tripled regular mask usage compared with control villages that received no interventions, the researchers found.
rafaelero 5y ago
Is this guy serious? It was not a split between 100% of group A using masks and 0% of group B using it. It was more like 40% / 15%. Is it that easy to become a tenure in Harvard? I think I am applying.

SubiculumCode 5y ago

I think this thread is a decent refutation that the CI lower bound was at 0: "First, the 11% reduction comes from a 30% increase in mask-use. The IV estimate (naively scaling things linearly) would thus be more like a 37% reduction in COVID from going from zero to universal masking." "Second, we find much larger effects among the elderly (a 35% reduction among 60+ without the above scaling). This suggests that the total reduction in morbidity and mortality from universal masking may be considerably larger than even the 37% number, perhaps more than 50%." "Third, it's not quite an apples to apples comparison because we are estimating the community impact of masks, whereas the vaccine studies only isolate the individual protective effect. The efficacy of vaccines at the population level may be larger than trials imply." https://twitter.com/Jabaluck/status/1433129444940599296 https://twitter.com/Jabaluck/status/1433129444940599296

dragontamer 5y ago

EDIT: Woops, read wrong. Lemme post the quote instead. > The observers found that just over 13% of people in the villages that received no interventions wore a mask properly, compared with more than 42% of people in the villages where each household received free masks and in-person reminders to wear them So an increase of 13% masking to 42% masking led to an 11% effective drop in COVID19 spread. So even though 70% of people weren't affected (either the 13% who wore a mask anyway, or the 60% of people who ignored the mask advice), you still had a measurable decrease in COVID19 spread. Which means masking mandates / masking propaganda works. Even with the huge number of people who ignore it, its still an effective means to cut down on COVID19 spread.

slg 5y ago

Except that was not what was tested. Here is what they did: >No-cost free masks distribution - One-third of the intervention villages received a cloth mask and two-thirds of the intervention villages received a surgical mask[5] during household distribution and distribution at marketplaces and other public locations weekly or every fortnight. Masks were also distributed at mosques on three Fridays during the first four weeks of the intervention. >Offering information on mask-wearing - Along with the distribution, the research team showed a brief video of notable public figures discussing why, how, and when to wear a mask. The video featured the Honorable Prime Minister of Bangladesh Sheikh Hasina, the head of the national Imam Training Academy, and the national cricket star Shakib Al Hasan. During the distribution visit, households also received a brochure based on WHO materials depicting proper mask wearing. >Reinforcement in-person and in public - In an effort to create a social norm, mask promoters encouraged non-mask wearers to wear a mask, providing a mask if the individual did not have one. Mask promoters also played public service announcements in public areas using handheld microphones. >Modeling and endorsement by trusted leaders. - Religious leaders (imams) discussed the importance of mask-wearing at Friday prayers from a scripted speech provided by the research team. This is a test of the effectiveness of these public policies and not the effectiveness of masks in general.

kragen 5y ago
Hmm, are you suggesting that those public policies might have had an impact on covid transmission that wasn't mediated through mask-wearing? For example, having the imams discuss the importance of mask-wearing might discourage people from going to Friday prayers? That seems unlikely but conceivable.
- Volundr 5y ago
  Not really. What's being suggested is that what's being tested is both societal compliance combined with mask effectiveness. To dramatically over simplify, let's assume we have a population of 10, none of them mask wearers. Let's also assume masks are 100% effective at preventing Covid infection. These measures convince only 1 person to wear a mask. In the control group (no advocacy) 10/10 are infected. In the study group 9/10 are because that one person wore a mask. So we've got an effectiveness of 10%, despite masks in our contrived example being 100% effective. The effectiveness is blunted by lack of compliance.

input_sh 5y ago

And then see this response to that claim by one of the study's authors: https://mobile.twitter.com/Jabaluck/status/1433129444940599296 https://mobile.twitter.com/Jabaluck/status/14331294449405992...

barbazoo 5y ago
which seems to have been deleted in the meantime
kragen 5y ago
Better link: https://birdsite.xanny.family/Jabaluck/status/1433129444940599296 https://birdsite.xanny.family/Jabaluck/status/14331294449405...
- input_sh 5y ago
  I wouldn't really call it better if it doesn't have a proper certificate.

weaksauce 5y ago

because compliance was voluntary... the study merely had leaders in the community wear masks and provided free masks to those that wanted them plus education and reminders; it wasn't a compulsory thing so this is mainly a lower bound on effectiveness. > Providing free masks, informing people about the importance of covering both the mouth and nose, reminding people in-person when they were unmasked in public, and role-modeling by community leaders tripled regular mask usage compared with control villages that received no interventions, the researchers found.

rafaelero 5y ago

Is this guy serious? It was not a split between 100% of group A using masks and 0% of group B using it. It was more like 40% / 15%. Is it that easy to become a tenure in Harvard? I think I am applying.