3 ms·

> 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 con

by 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.
- timr 5y ago
  > Instead the study shows that mask wearing combined with other factors have a clear and unquestionable correlation with reduce Covid spread. The study shows that cloth masks (combined with other factors) have no effect on seroprevalence. It shows that surgical masks (combined with other factors) has a small-but-significant effect on seroprevalence. The confidence interval on the surgical mask group overlaps zero, so you can't rule out "no effect". At these small effect sizes, you also can't rule out the role of confounders -- it's possible that behavior change could explain all of it. In short, neither result is "clear and unquestionable". An accurate description of the results are that they are "weak and debatable".
  - rualca 5y ago
    > The study shows that cloth masks (combined with other factors) have no effect on seroprevalence. No, not really. If you happen to take a few minutes to read the paper, you'll notice that the study was conducted with a type of cloth mask produced locally which had a filtration efficiency rate of around 37% with a standard deviation of 6%, compared with the surgical mask's filtration efficiency of 95%. The study also points out that the filtration efficiency of surgical masks washed 10 times with soap was 76%, and that they evaluated a type of cloth mask which can achieve a filtration efficiency of 60%. Thus, what the study actually states is that they observed that wearing poor quality cloth masks showed high-variance results whose confidence interval includes the point estimate for surgical masks. In other words, the study actually pointed out that using a specific type of cloth mask produced locally and which was known to have poor filtering efficiency had an effect that lies somewhere between being as good as surgical masks and not wearing anything at all. > The confidence interval on the surgical mask group overlaps zero, so you can't rule out "no effect". No, not really. That's not how confidence intervals work. At most, the only conclusion you can objectively draw from the data is that even though the positive effect of wearing surgical masks in the past study is clear and beyond doubt, further studies would be required to increase the resolution of that estimate. In fact, if you happen to read the study you'll notice that the conclution states quite clearly that "We found clear evidence that surgical masks are effective in reducing symptomatic seropreva- lence of SARS-CoV-2; while cloth masks clearly reduce symptoms, we cannot reject that they have zero or only a small impact on symptomatic SARS-CoV-2 infections (perhaps reducing symptoms of other respiratory diseases)." Also, your comments feel like a mix of moving the goalpost combined with a considerable amount of cherry-picking. It's a widely known fact that the whole point of wearing masks is primarily to reduce the viral load emitted by the wearer, and a minor benefit is to reduce our own exposure to the virus. Thus I feel that you're trying to misrepresent the whole point of wearing masks by trying to frame it as a "seroprevalence" issue. That was never, at any point in time, the reason why we have the social obligation to wear face masks and respect social distancing.
    - timr 5y ago
      > If you happen to take a few minutes to read the paper, you'll notice that the study was conducted with a type of cloth mask produced locally which had a filtration efficiency rate of around 37% with a standard deviation of 6%, compared with the surgical mask's filtration efficiency of 95%. I read it, thanks. The mask they used was much better than what most people are wearing: > The cloth mask had an exterior layer of 100% non-woven polypropylene (70 grams/square meter [gsm]), two interior layers of 60% cotton / 40% polyester interlocking knit (190 gsm), an elastic loop that goes around the head above and below the ears, and a nose bridge If a cloth mask with three layers of different materials and a nose bridge is dramatically less efficient than a simple surgical mask, then that's pretty damning for the whole idea of a cloth mask, in general.

by timr 5y ago

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.

timr 5y ago
> Instead the study shows that mask wearing combined with other factors have a clear and unquestionable correlation with reduce Covid spread. The study shows that cloth masks (combined with other factors) have no effect on seroprevalence. It shows that surgical masks (combined with other factors) has a small-but-significant effect on seroprevalence. The confidence interval on the surgical mask group overlaps zero, so you can't rule out "no effect". At these small effect sizes, you also can't rule out the role of confounders -- it's possible that behavior change could explain all of it. In short, neither result is "clear and unquestionable". An accurate description of the results are that they are "weak and debatable".
- rualca 5y ago
  > The study shows that cloth masks (combined with other factors) have no effect on seroprevalence. No, not really. If you happen to take a few minutes to read the paper, you'll notice that the study was conducted with a type of cloth mask produced locally which had a filtration efficiency rate of around 37% with a standard deviation of 6%, compared with the surgical mask's filtration efficiency of 95%. The study also points out that the filtration efficiency of surgical masks washed 10 times with soap was 76%, and that they evaluated a type of cloth mask which can achieve a filtration efficiency of 60%. Thus, what the study actually states is that they observed that wearing poor quality cloth masks showed high-variance results whose confidence interval includes the point estimate for surgical masks. In other words, the study actually pointed out that using a specific type of cloth mask produced locally and which was known to have poor filtering efficiency had an effect that lies somewhere between being as good as surgical masks and not wearing anything at all. > The confidence interval on the surgical mask group overlaps zero, so you can't rule out "no effect". No, not really. That's not how confidence intervals work. At most, the only conclusion you can objectively draw from the data is that even though the positive effect of wearing surgical masks in the past study is clear and beyond doubt, further studies would be required to increase the resolution of that estimate. In fact, if you happen to read the study you'll notice that the conclution states quite clearly that "We found clear evidence that surgical masks are effective in reducing symptomatic seropreva- lence of SARS-CoV-2; while cloth masks clearly reduce symptoms, we cannot reject that they have zero or only a small impact on symptomatic SARS-CoV-2 infections (perhaps reducing symptoms of other respiratory diseases)." Also, your comments feel like a mix of moving the goalpost combined with a considerable amount of cherry-picking. It's a widely known fact that the whole point of wearing masks is primarily to reduce the viral load emitted by the wearer, and a minor benefit is to reduce our own exposure to the virus. Thus I feel that you're trying to misrepresent the whole point of wearing masks by trying to frame it as a "seroprevalence" issue. That was never, at any point in time, the reason why we have the social obligation to wear face masks and respect social distancing.
  - timr 5y ago
    > If you happen to take a few minutes to read the paper, you'll notice that the study was conducted with a type of cloth mask produced locally which had a filtration efficiency rate of around 37% with a standard deviation of 6%, compared with the surgical mask's filtration efficiency of 95%. I read it, thanks. The mask they used was much better than what most people are wearing: > The cloth mask had an exterior layer of 100% non-woven polypropylene (70 grams/square meter [gsm]), two interior layers of 60% cotton / 40% polyester interlocking knit (190 gsm), an elastic loop that goes around the head above and below the ears, and a nose bridge If a cloth mask with three layers of different materials and a nose bridge is dramatically less efficient than a simple surgical mask, then that's pretty damning for the whole idea of a cloth mask, in general.