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Surgical masks do reduce the spread of COVID-19, and even cloth masks reduce symptoms of respiratory illness. [1] During an emergency, we have to act. It's absu

Surgical masks do reduce the spread of COVID-19, and even cloth masks reduce symptoms of respiratory illness. [1] During an emergency, we have to act. It's absurd to expect that we should wait for a huge study to confirm what we we already know about respiratory viruses in general. In a low-info environment, the prior is clearly to favor mask mandates. And it turns out, it was the right call! [1] "Surgical masks reduce COVID-19 spread, large-scale study shows" https://med.stanford.edu/news/all-news/2021/09/surgical-masks-covid-19.html https://med.stanford.edu/news/all-news/2021/09/surgical-mask...

timr 4y ago
Let's be clear on the limits of the study you're quoting -- the total effect size was a tiny, tiny fraction a percent for the surgical mask arm (.09%), and barely reached a reasonable level of statistical significance (p=0.043). There was no statistically significant effect size for cloth masks. No matter how you look at this study -- if you actually read it [1], and don't just read press releases -- it was not a strong result. Moreover, after the raw data for the study was released, there were a number of legitimate critiques that call into question the primary result. For example, this one [2]: > In this short note we re-analyze the data from this trial using standard non-parametric paired statistics tests on treatment/village pairs. With this approach, we find that behavioral outcomes like physical distancing are highly significant, while the primary outcome of the study is not. Importantly, we find that the behavior of unblinded staff when enrolling study participants is one of the most highly significant differences between treatment and control groups, contributing to a significant imbalance in denominators between treatment and control groups. Even if we accept the claims of the original paper at face value, the fact that you're citing this study as some kind of definitive rebuttal is, deeply ironically, a perfect example of the OP's critique: the highest quality evidence for mask mandates is simply and objectively weak, but most casual observers believe the opposite to be true. Public health has exaggerated (or outright lied about) evidence quality throughout the Covid-19 pandemic. Is that the reason for this Polio event? Likely not, but if we're casting about for secondary or tertiary reasons, a drop in trust in public health due to their own trivially falsified propaganda wouldn't be the worst place to start. [1] https://www.poverty-action.org/sites/default/files/publications/Mask_RCT____Symptomatic_Seropositivity_083121.pdf https://www.poverty-action.org/sites/default/files/publicati... [2] https://arxiv.org/abs/2112.01296 https://arxiv.org/abs/2112.01296
wrycoder 4y ago
I’d like to second timr’s remarks on that study. I’ve read the whole thing twice, and I found it to be low quality and tendentious: they didn’t even fairly present the results they did have. It may be that the “surgical” masks they used, while not N95, had an electret layer. That would make them a lot better than the “procedure” masks commonly worn in the US against COVID.
surement 4y ago
Do you have evidence that asymptomatic people are even contagious? At the start of the pandemic there was a Pew survey that showed that 10% of people who know they have covid would still go to work. I think stuff like that explains the spread a lot more than lack of masking by non-sick individuals. Not everyone can afford to quarantine.
- mcguire 4y ago
  18 Nov 2020 "Research early in the pandemic suggested that the rate of asymptomatic infections could be as high as 81%. But a meta-analysis published last month1, which included 13 studies involving 21,708 people, calculated the rate of asymptomatic presentation to be 17%. ... Byambasuren’s review also found that asymptomatic individuals were 42% less likely to transmit the virus than symptomatic people." (https://www.nature.com/articles/d41586-020-03141-3 https://www.nature.com/articles/d41586-020-03141-3) 7 Jan 2021 "The baseline assumptions for the model were that peak infectiousness occurred at the median of symptom onset and that 30% of individuals with infection never develop symptoms and are 75% as infectious as those who do develop symptoms. Combined, these baseline assumptions imply that persons with infection who never develop symptoms may account for approximately 24% of all transmission." (https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2774707 https://jamanetwork.com/journals/jamanetworkopen/fullarticle...)

timr 4y ago

Let's be clear on the limits of the study you're quoting -- the total effect size was a tiny, tiny fraction a percent for the surgical mask arm (.09%), and barely reached a reasonable level of statistical significance (p=0.043). There was no statistically significant effect size for cloth masks. No matter how you look at this study -- if you actually read it [1], and don't just read press releases -- it was not a strong result. Moreover, after the raw data for the study was released, there were a number of legitimate critiques that call into question the primary result. For example, this one [2]: > In this short note we re-analyze the data from this trial using standard non-parametric paired statistics tests on treatment/village pairs. With this approach, we find that behavioral outcomes like physical distancing are highly significant, while the primary outcome of the study is not. Importantly, we find that the behavior of unblinded staff when enrolling study participants is one of the most highly significant differences between treatment and control groups, contributing to a significant imbalance in denominators between treatment and control groups. Even if we accept the claims of the original paper at face value, the fact that you're citing this study as some kind of definitive rebuttal is, deeply ironically, a perfect example of the OP's critique: the highest quality evidence for mask mandates is simply and objectively weak, but most casual observers believe the opposite to be true. Public health has exaggerated (or outright lied about) evidence quality throughout the Covid-19 pandemic. Is that the reason for this Polio event? Likely not, but if we're casting about for secondary or tertiary reasons, a drop in trust in public health due to their own trivially falsified propaganda wouldn't be the worst place to start. [1] https://www.poverty-action.org/sites/default/files/publications/Mask_RCT____Symptomatic_Seropositivity_083121.pdf https://www.poverty-action.org/sites/default/files/publicati... [2] https://arxiv.org/abs/2112.01296 https://arxiv.org/abs/2112.01296

wrycoder 4y ago

I’d like to second timr’s remarks on that study. I’ve read the whole thing twice, and I found it to be low quality and tendentious: they didn’t even fairly present the results they did have. It may be that the “surgical” masks they used, while not N95, had an electret layer. That would make them a lot better than the “procedure” masks commonly worn in the US against COVID.

surement 4y ago

Do you have evidence that asymptomatic people are even contagious? At the start of the pandemic there was a Pew survey that showed that 10% of people who know they have covid would still go to work. I think stuff like that explains the spread a lot more than lack of masking by non-sick individuals. Not everyone can afford to quarantine.

mcguire 4y ago
18 Nov 2020 "Research early in the pandemic suggested that the rate of asymptomatic infections could be as high as 81%. But a meta-analysis published last month1, which included 13 studies involving 21,708 people, calculated the rate of asymptomatic presentation to be 17%. ... Byambasuren’s review also found that asymptomatic individuals were 42% less likely to transmit the virus than symptomatic people." (https://www.nature.com/articles/d41586-020-03141-3 https://www.nature.com/articles/d41586-020-03141-3) 7 Jan 2021 "The baseline assumptions for the model were that peak infectiousness occurred at the median of symptom onset and that 30% of individuals with infection never develop symptoms and are 75% as infectious as those who do develop symptoms. Combined, these baseline assumptions imply that persons with infection who never develop symptoms may account for approximately 24% of all transmission." (https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2774707 https://jamanetwork.com/journals/jamanetworkopen/fullarticle...)