5 ms·

>It's surprising to me that cloth masks can't even do the 11% of surgical masks. Just want to add clarification here. The 11% number is the community impact of

by slg 5y ago

>It's surprising to me that cloth masks can't even do the 11% of surgical masks. Just want to add clarification here. The 11% number is the community impact of the programs designed to increase mask usage. It is not the effectiveness of a mask on an individual level. That number will be much higher since as you said a number of people didn't/don't comply at a societal level.

majormajor 5y ago
Thanks! I edited my comment to add notes on that too. At a population level even a small portion of the population wearing masks reducing overall spread is very good to see. Even for surgical masks.
timr 5y ago
> That number will be much higher since as you said a number of people didn't/don't comply at a societal level. ...or it will be lower. The study confounds the effects of distancing and mask-wearing. Distancing was higher in the surgical mask cohort. Also, as others note, the confidence interval for the surgical mask group overlaps zero. You can't rule out that the observed effect is due to chance.
- clairity 5y ago
  yes, distancing does most of the work in most common situations. a mask can only work when conversing closely for a time indoors. otherwise masks do nothing, no matter the filtration rate of the mask, because there's nothing to filter in the first place. distancing is a more universal and sensible mitigation (we're distanced from nearly all of the world population all the time). this is why mask mandates, as currently constructed, are misguided and ignorant at best. the mandate should be to wear a mask when you're intimately sharing air (within ~3ft/1m) with another person indoors. the reason we don't have that sort of mandate is because it would mean we'd have to wear them around friends and family rather than those gross strangers who are out to kill us with their ignorance and malice (they're not). this is also why the current mandates for restaurants (and most retail) makes no sense, as we're only going to be intimately sharing air with our friends and family in those places anyway.
  - YZF 5y ago
    Aren't you sharing air with others in any common indoors space? I thought that was the whole aerosols debate that's basically settled by now, i.e. virus can stay suspending in the air for extended periods. With the Delta variant's characteristics this is also a much bigger problem (i.e. the same indoor space that might have been ok is no longer ok). There were early studies with the less infectious variants that showed how people situated far from each other in indoors spaces infect each other. So the mandate for masking in any common indoor space seems to make a lot of sense.
    - clairity 5y ago
      no, it's not "settled science" like that. the virus must traverse a gauntlet of death before reaching your juicy mucus membranes, including dessication and all manner of external forces that will inactivate it in the meantime. it falls apart in droves outside the body. you need constant exposure to warm, moist, infected exhaust so that the virus has trillions of chances of taking hold in your respiratory system, and it likely takes millions of virus particles making it across for enough to survive the immune response gauntlet inside the body. that a few virus particles in controlled tests miraculously manage to exist for a few minutes in the air has no bearing on real-world transmission rates. that's why a mask can work (better than distancing) in that one particular situation, but distancing is a better general mitigation. by the way, those early "studies" on long indoor spread were conjecture-based (e.g., using models), not rigorous science, and have failed to replicate.
      - YZF 5y ago
        I'm not talking about model studies. I am talking about case studies, like: https://www.nytimes.com/2020/04/20/health/airflow-coronavirus-restaurants.html https://www.nytimes.com/2020/04/20/health/airflow-coronaviru... Also: https://www.the-scientist.com/news-opinion/ferret-study-reinforces-role-of-aerosols-in-sars-cov-2-spread-68094 https://www.the-scientist.com/news-opinion/ferret-study-rein... Even early on with the Diamond Princess you've seen wide spread of the virus despite passengers being largely confined to their cabins. There were multiple other examples. We also know the Delta variant is more infectious. I'm not saying distancing doesn't work. Even if you assume the virus is spread in the indoors air it's not a terrible bad assumptions to think that a person emitting virus continuously will have a higher concentration of virus in their immediate vicinity. So sure, it's layers of defense. The mask is also about limiting the emissions in the first place and distancing indoors is not always practical in public busy spaces. But sure. It is not settled science. Science takes time. If your point is that we don't understand exactly what happens then sure, but we rarely do for anything in this field anyways.
- slg 5y ago
  From the study: >The intervention increased proper mask-wearing from 13.3% in control villages (N=806,547 observations) to 42.3% in treatment villages (N=797,715 observations)... Physical distancing increased from 24.1% in control villages to 29.2% in treatment villages Mask wearing increased 218% while distancing increased by 21%. I agree this is not proof specifically about masks, the study is about specific public policy programs and not mask wearing in general, but it certainly seems like masks wearing is the biggest contributor to the reduction seen.
  - hvac 5y ago
    I think it's also important to note that there was no change in physical distancing seen in indoor environments (mosques) - maybe due to the fact that it's obviously easier to spread out when outdoors. I think we are fairly confident by now that the vast majority of spread occurs indoors [1]. [1] https://academic.oup.com/jid/article/223/4/550/6009483 https://academic.oup.com/jid/article/223/4/550/6009483
  - timr 5y ago
    > Mask wearing increased 218% while distancing increased by 21%. You can't just compare "percentage change" of two wildly different things, and leap to the conclusion that the magnitude of change is causal. It begs the entire question: if physical distancing works well, and mask wearing does not work, you could increase mask wearing by whatever percentage you like, and a smaller change in physical distancing would still overwhelm it. We don't know. But aside from that, you skipped over an important part of what I said: distancing was higher in the surgical mask group. See Table 2.
    - rualca 5y ago
      > It begs the entire question: if physical distancing works well, and mask wearing does not work (...) There's nothing in the study remotely suggesting that masks have no effect. Instead the study shows that mask wearing combined with other factors have a clear and unquestionable correlation with reduce Covid spread. Even if you wish to nitpick the contribution of mask wearing in the reduction in Covid spread, it makes absolutely no sense at all to jump to the conclusion that surgical masks have no impact in spreading airborne pathogens as that's precisely what surgical masks do and the whole reason why they are extensively used by the medical community for decades.
kragen 5y ago
Given a really effective intervention for a contagious disease, the effectiveness on a community level will be much lower on an individual level. Think about PRC vs. USA: 4636 deaths in PRC, 618591 deaths in USA, even though it's a four times smaller country. There is no measure that even comes close to reducing your risk of death from covid by a factor of 600 on an individual level, but because they were able to get the R number down below 1, they stopped the epidemic. Normally you would expect effective contagion control measures to have an exponentially larger effect at a societal level than it does at an individual level, even if you don't reach the critical threshold to stop the epidemic: if you can drop R from 2.0 to 1.9, that reduces your individual risk by 5%, but it also reduces the number of cases in the next generation by 5%, the number of cases in the generation after that by 10%, the number of cases in the generation after that by 14%, etc. After 20 generations of transmission you've reduced the number of cases by 64%, which reduces everyone's infection risk by 64%. Of course, with such a high exponential growth rate, that only means that people get infected 1.6 generations later at that point, but if you're comparing different communities at the same time, the difference is about 3:1. So it seems like probably the effectiveness of the mask on an individual level was truly tiny.
- 908B64B197 5y ago
  > Think about PRC vs. USA: 4636 deaths in PRC, 618591 deaths in USA, even though it's a four times smaller country. 4636 deaths as reported by the CCP to foreign journalists. Same party whose official line is that nothing happened in Tiananmen Square.
  - kragen 5y ago
    This is nonsense, partisan propaganda masquerading as rational thought. Nevertheless, there are many countries that had similarly effective infection control, so even if you choose to believe your hate for China instead of the best unbiased assessments, check out New Zealand, Vietnam, ROC, Thailand, or Australia.
- gunapologist99 5y ago
  > 4636 deaths in PRC That number is completely laughable. It's literally communist propaganda.

by slg 5y ago

majormajor 5y ago

Thanks! I edited my comment to add notes on that too. At a population level even a small portion of the population wearing masks reducing overall spread is very good to see. Even for surgical masks.

timr 5y ago

> That number will be much higher since as you said a number of people didn't/don't comply at a societal level. ...or it will be lower. The study confounds the effects of distancing and mask-wearing. Distancing was higher in the surgical mask cohort. Also, as others note, the confidence interval for the surgical mask group overlaps zero. You can't rule out that the observed effect is due to chance.

clairity 5y ago
yes, distancing does most of the work in most common situations. a mask can only work when conversing closely for a time indoors. otherwise masks do nothing, no matter the filtration rate of the mask, because there's nothing to filter in the first place. distancing is a more universal and sensible mitigation (we're distanced from nearly all of the world population all the time). this is why mask mandates, as currently constructed, are misguided and ignorant at best. the mandate should be to wear a mask when you're intimately sharing air (within ~3ft/1m) with another person indoors. the reason we don't have that sort of mandate is because it would mean we'd have to wear them around friends and family rather than those gross strangers who are out to kill us with their ignorance and malice (they're not). this is also why the current mandates for restaurants (and most retail) makes no sense, as we're only going to be intimately sharing air with our friends and family in those places anyway.
- YZF 5y ago
  Aren't you sharing air with others in any common indoors space? I thought that was the whole aerosols debate that's basically settled by now, i.e. virus can stay suspending in the air for extended periods. With the Delta variant's characteristics this is also a much bigger problem (i.e. the same indoor space that might have been ok is no longer ok). There were early studies with the less infectious variants that showed how people situated far from each other in indoors spaces infect each other. So the mandate for masking in any common indoor space seems to make a lot of sense.
  - clairity 5y ago
    no, it's not "settled science" like that. the virus must traverse a gauntlet of death before reaching your juicy mucus membranes, including dessication and all manner of external forces that will inactivate it in the meantime. it falls apart in droves outside the body. you need constant exposure to warm, moist, infected exhaust so that the virus has trillions of chances of taking hold in your respiratory system, and it likely takes millions of virus particles making it across for enough to survive the immune response gauntlet inside the body. that a few virus particles in controlled tests miraculously manage to exist for a few minutes in the air has no bearing on real-world transmission rates. that's why a mask can work (better than distancing) in that one particular situation, but distancing is a better general mitigation. by the way, those early "studies" on long indoor spread were conjecture-based (e.g., using models), not rigorous science, and have failed to replicate.
    - YZF 5y ago
      I'm not talking about model studies. I am talking about case studies, like: https://www.nytimes.com/2020/04/20/health/airflow-coronavirus-restaurants.html https://www.nytimes.com/2020/04/20/health/airflow-coronaviru... Also: https://www.the-scientist.com/news-opinion/ferret-study-reinforces-role-of-aerosols-in-sars-cov-2-spread-68094 https://www.the-scientist.com/news-opinion/ferret-study-rein... Even early on with the Diamond Princess you've seen wide spread of the virus despite passengers being largely confined to their cabins. There were multiple other examples. We also know the Delta variant is more infectious. I'm not saying distancing doesn't work. Even if you assume the virus is spread in the indoors air it's not a terrible bad assumptions to think that a person emitting virus continuously will have a higher concentration of virus in their immediate vicinity. So sure, it's layers of defense. The mask is also about limiting the emissions in the first place and distancing indoors is not always practical in public busy spaces. But sure. It is not settled science. Science takes time. If your point is that we don't understand exactly what happens then sure, but we rarely do for anything in this field anyways.
slg 5y ago
From the study: >The intervention increased proper mask-wearing from 13.3% in control villages (N=806,547 observations) to 42.3% in treatment villages (N=797,715 observations)... Physical distancing increased from 24.1% in control villages to 29.2% in treatment villages Mask wearing increased 218% while distancing increased by 21%. I agree this is not proof specifically about masks, the study is about specific public policy programs and not mask wearing in general, but it certainly seems like masks wearing is the biggest contributor to the reduction seen.
- hvac 5y ago
  I think it's also important to note that there was no change in physical distancing seen in indoor environments (mosques) - maybe due to the fact that it's obviously easier to spread out when outdoors. I think we are fairly confident by now that the vast majority of spread occurs indoors [1]. [1] https://academic.oup.com/jid/article/223/4/550/6009483 https://academic.oup.com/jid/article/223/4/550/6009483
- timr 5y ago
  > Mask wearing increased 218% while distancing increased by 21%. You can't just compare "percentage change" of two wildly different things, and leap to the conclusion that the magnitude of change is causal. It begs the entire question: if physical distancing works well, and mask wearing does not work, you could increase mask wearing by whatever percentage you like, and a smaller change in physical distancing would still overwhelm it. We don't know. But aside from that, you skipped over an important part of what I said: distancing was higher in the surgical mask group. See Table 2.
  - rualca 5y ago
    > It begs the entire question: if physical distancing works well, and mask wearing does not work (...) There's nothing in the study remotely suggesting that masks have no effect. Instead the study shows that mask wearing combined with other factors have a clear and unquestionable correlation with reduce Covid spread. Even if you wish to nitpick the contribution of mask wearing in the reduction in Covid spread, it makes absolutely no sense at all to jump to the conclusion that surgical masks have no impact in spreading airborne pathogens as that's precisely what surgical masks do and the whole reason why they are extensively used by the medical community for decades.

kragen 5y ago

Given a really effective intervention for a contagious disease, the effectiveness on a community level will be much lower on an individual level. Think about PRC vs. USA: 4636 deaths in PRC, 618591 deaths in USA, even though it's a four times smaller country. There is no measure that even comes close to reducing your risk of death from covid by a factor of 600 on an individual level, but because they were able to get the R number down below 1, they stopped the epidemic. Normally you would expect effective contagion control measures to have an exponentially larger effect at a societal level than it does at an individual level, even if you don't reach the critical threshold to stop the epidemic: if you can drop R from 2.0 to 1.9, that reduces your individual risk by 5%, but it also reduces the number of cases in the next generation by 5%, the number of cases in the generation after that by 10%, the number of cases in the generation after that by 14%, etc. After 20 generations of transmission you've reduced the number of cases by 64%, which reduces everyone's infection risk by 64%. Of course, with such a high exponential growth rate, that only means that people get infected 1.6 generations later at that point, but if you're comparing different communities at the same time, the difference is about 3:1. So it seems like probably the effectiveness of the mask on an individual level was truly tiny.

908B64B197 5y ago
> Think about PRC vs. USA: 4636 deaths in PRC, 618591 deaths in USA, even though it's a four times smaller country. 4636 deaths as reported by the CCP to foreign journalists. Same party whose official line is that nothing happened in Tiananmen Square.
- kragen 5y ago
  This is nonsense, partisan propaganda masquerading as rational thought. Nevertheless, there are many countries that had similarly effective infection control, so even if you choose to believe your hate for China instead of the best unbiased assessments, check out New Zealand, Vietnam, ROC, Thailand, or Australia.
gunapologist99 5y ago
> 4636 deaths in PRC That number is completely laughable. It's literally communist propaganda.