Surgical masks reduce Covid-19 spread, large-scale Stanford study shows
1–10 of 235 posts
Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows
#2> The researchers enrolled nearly 350,000 people from 600 villages in rural Bangladesh
Wow. I was about to complain about "small n", but... an experiment of this size is not small at all. Congrats on the researchers on doing such a big study!
Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows
#3> There were significantly fewer COVID-19 cases in villages with surgical masks compared with the control villages. (Although there were also fewer COVID-19 cases in villages with cloth masks as compared to control villages, the difference was not statistically significant.) This aligns with lab tests showing that surgical masks have better filtration than cloth masks. However, cloth masks did reduce the overall likelihood of experiencing symptoms of respiratory illness during the study period.
I think this is probably the most interesting part, and worth watching in future studies.
Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows
#4From 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/14332026511062016...
Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows
#5From 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/14332026511062016...
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."
Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows
#6This is truly great news, as we've need some controlled studies.
However, _mandates_, literally threatening people with police violence, bodily or financial harm, is not the correct way forward.
I think the best solution is improved mandates for airflow. It's a lot easier to improve airflow in a building than it is to police and enforce a mask mandate.
Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows
#7From 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/14332026511062016...
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.
Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows
#8From 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/14332026511062016...
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.
Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows
#9From 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/14332026511062016...
And then see this response to that claim by one of the study's authors: https://mobile.twitter.com/Jabaluck/status/14331294449405992...
Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows
#10alternate hypothesis is statistically insignificant. with a 300k sample size a p-value 0.04. damn.