You have to read a footnote in the original paper to understand that the “surgical” masks used actually contained a blown fiber layer, like N95s, and passed the 95% filtration level when tested.
These are not the surgical/procedure masks that we see people commonly wearing in the US.
Not only that, but they cost thirteen cents apiece.
Why don’t we have those in the US?
Edit: it’s not a very good trial, because mask compliance was poor in spite of their efforts, and they didn’t separate the mask wearing groups when evaluating the outcomes, though they could have.
I would have expected better results from the “surgical” masks.
You really have to read the original paper to assess this trial properly.
Great points. It’s worth adding that SARS-COV-2 is spread primarily through the air via extremely tiny droplets (< 5 μm) [1]. Breathing, coughing, and sneezing produces infectious aerosols which can remain suspended in the air for hours. Most cloth masks that are used by the general public will provide very little protection against inhaling or producing these aerosols [2], though such masks are likely to help reduce the spread of larger droplets.
> “surgical” masks used actually contained a blown fiber layer, like N95s, and passed the 95% filtration level when tested.
> The study’s authors found that surgical masks — but not cloth masks — reduced transmission of SARS-CoV-2 in villages where the research team distributed face masks and promoted their use.
West coast city: 90% of the people I see around wear useless cloth masks. Borders on criminal that we pretend the mask-as-virtue-statement circus we are currently undergoing has any benefit other than reduced oxygen flow.
We've gone from quoting a part of the article leaving out the part that discusses cloth mask efficacy to full blown denial of what the study concludes about cloth masks, regurgitation tired old anti-mask rhetoric.
Consider taking it up with Lynne Peeples. The very subtitle of the piece is 'surgical masks are highly protective, but cloth masks fall short', I have no idea why she thinks '11% drop in risk' is 'highly protective', but '5% drop' is 'falling short'. Either way the numbers appear marginal at best.
Edit: Fundamentally I have an issue with any definition of risk that bounds the measure to a short time frame. For all we know the mask intervention may slow the spread speed by a small factor, but were we to measure over a year (or even longer) we might observe the same total number of infections: the virus is going to infect everyone susceptible, only at a slightly slower pace.
1. Based on the size of the study there are thresholds for statistical significance.
2. Only a portion of the people were even wearing masks. A few people wore masks and the risk of infection dropped by a few percent. Declaring masks don't work because a couple people wore them yet the entire population didn't see a complete decline in infection is illogical and dishonest.
3. The study not being able to conclude in a statistically significant way that cloth masks prevent infection is completely different from concluding that cloth masks are worthless. Your aversion to masks is completely a reflection of your bias and not supported by this study.
Yes, and as I wrote in another comment, that is completely different from concluding that cloth masks don't work. You're drawing a conclusion that the data doesn't support.
> You're drawing a conclusion that the data doesn't support.
I'm telling you the conclusions of the paper. Your faith in masks is an entirely separate question that is clearly unaffected by the data here, because it requires proving a negative.
Is it possible that cloth masks actually work, and this huge study failed to find any significant effect? Anything is possible, but the results here are indistinguishable from noise, and don't support the claim. And with every RCT that gets published showing negligible effect from community masking, the probability that the claim is true gets smaller.
Oxygen is smaller and easier to pass the filters than COVID-19 particles. It's possible not to have reduced oxygen flow but protect against the virus, but physically impossible to do the reverse as you suggest.
That's nice in theory. In practice I have reduced lung capacity and start suffocating after 15 mins of N95. What happens is that the whole air flow is harder to push around, and there is so long one can force breath. I presume that people with healthier lungs have an easier time dealing with it, but I find it very hard to believe the impact is zero.
> Myth: Face masks can reduce oxygen getting to the lungs and bloodstream
> ... Some masks mean you have to put more effort into breathing if you wear them for a long time.
> ... If worn for many hours without a break, an N95 mask might potentially affect oxygen levels but likely not to a dangerous extent, especially in people who are healthy.
'put more effort into breathing' aka 'suffocating at normal breath patterns'. Oh, and it actually does reduce the oxygen levels, but rest assured citizen, it is nothing to worry about. It's just a myth. There is a word I'm looking for here, miss, misty, aha, misinformation.
I never said masks couldn't affect airflow and thus oxygen. I said a mask cannot affect airflow and thus oxygen more than it affects COVID. That is, the "masks do nothing to prevent COVID but cut off air supply" arguments are dumb.
Personally, I don't consider that reduced airflow relevant to me or anyone I know. The people with reduced lung capacity do complain about having trouble after 15 minutes, but continue to wear them. In fact, people with reduced lung function are the most aggressive mask wearers I know.
Free advice: Don't wear a mask if you have a day-long interview at a FAANG. Don't wear a mask if you participate in an athletic competition. You won't get peak performance for either intellectual or physical activities. Masks are not zero cost, they reduce airflow. And their effectiveness against covid spread remains to be proven, especially as strains get more and more infectious.
Now consider that kids are forced to wear cloth masks all day long, day after day after day. This is a choice, there are places in the world where they are just as serious about covid as US, and yet kids can stay in class without masks.
It's a rough tradeoff. I wish we could have an adult conversation, not pretend there are no minuses and masks are a no brainer in all situations. We have replaced conversation with Twitter sloganeering.
> In secondary education, teachers and pupils who have been fully vaccinated for at least two weeks won't have to quarantine after contact with someone who has the coronavirus. Only unvaccinated teachers and -students need to take a self-test twice a week. Teachers and students need to maintain social distancing, and face masks are mandatory in corridors and canteens.
> In primary education, adults like teachers and parents must keep 1.5 meters apart. But for the kids, no restrictions apply other than the general rules like washing your hands regularly and staying home if you have symptoms.
> Don't wear a mask if you have a day-long interview at a FAANG
Why on earth wouldn't I? My O2 levels don't seem to be too degraded by a mask. And, even if they were, I would never expect to be hired by people who saw me put them at risk. I'm not sure I would feel comfortable accepting a job from people who would hire someone who wasn't willing to wear a mask.
> I wish we could have an adult conversation, not pretend there are no minuses and masks are a no brainer in all situations.
I've never experienced a negative from wearing a mask. Some people are really opposed by I just don't get it. It makes as much sense to me as people not wearing a seat belt because they worry about chaffing.
> there are places in the world where they are just as serious about covid as US, and yet kids can stay in class without masks.
Every state that lets kids run around without masks produces news stories about COVID spreading like wildfire through the schools. I don't know why I would consider that acceptable. Kids should not be forced to get COVID for no reason.
The other important piece of information in that footnote is that filtration efficiency of cloth masks depend highly on their material and design. I wish it was possible to actually test the filtration efficiency of cloth and surgical masks available in the market.
Anyone who has actually read even the first few pages of the so called "gold standard" study cited knows it was useless and inapplicable to any meaningful public health practice. But the narrative MUST NOT BE deviated from. I don't think we as a modern civilization will recover for a hundred years from the way in which institutions like nature have debased themselves with political pandering.
Because they believe the best way to preserve their careers is to regurgitate official dogma. It becomes an absurd race of who's performing this ritual in the strongest possible terms. It's going to get worse, keep an eye for explicit adulation of the wisdom of the political authorities.
If there is any Russian speaker around, would be instructive to take one of the old top Soviet science publications and translate the TOC.
>> Neither the laboratory findings nor the mask-trial findings have been peer reviewed.
> Then why are Nature reporting on them in such conclusive language?
Given Nature has very well-regarded peer reviewers, it seems likely that this is an earlier report on something they expect to publish as peer reviewed. Why report it now? Because people are dying and this could help them.
Are they arguing over comma locations? Waiting until the next publication date? Who knows.
The study found an effect size of zero in the cloth mask cohort, and an 11% difference in the surgical mask cohort. Effect sizes that managed significance were just barely significant, at a p-value of 0.043. Also, the researchers didn't do any baseline serology, so it's quite difficult to know if there was a starting bias influencing the final results. It's also difficult to know the degree to which the non-blinded nature of the study and voluntary seroprevalence testing biased the outcome. At such small effect sizes, questions like these matter a great deal.
Nevertheless, it is encouraging that someone actually bothered to do a proper RCT of masking as "protection for others", and this study has several points that should be widely communicated (e.g. the ineffectiveness of cloth masks). However, I would not say that "masks passed their test" is really one of them...these results are pretty mediocre.
Vinay Prasad of UCSF has made an excellent summary of the results of the Bangladesh RCT, and I recommend it strongly:
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[ 3.0 ms ] story [ 52.8 ms ] threadThese are not the surgical/procedure masks that we see people commonly wearing in the US.
Not only that, but they cost thirteen cents apiece.
Why don’t we have those in the US?
Edit: it’s not a very good trial, because mask compliance was poor in spite of their efforts, and they didn’t separate the mask wearing groups when evaluating the outcomes, though they could have.
I would have expected better results from the “surgical” masks.
You really have to read the original paper to assess this trial properly.
[1] Airborne transmission of respiratory viruses https://www.science.org/lookup/doi/10.1126/science.abd9149
[2] Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks https://pubs.acs.org/doi/10.1021/acsnano.0c03252#
> The study’s authors found that surgical masks — but not cloth masks — reduced transmission of SARS-CoV-2 in villages where the research team distributed face masks and promoted their use.
West coast city: 90% of the people I see around wear useless cloth masks. Borders on criminal that we pretend the mask-as-virtue-statement circus we are currently undergoing has any benefit other than reduced oxygen flow.
Edit: Fundamentally I have an issue with any definition of risk that bounds the measure to a short time frame. For all we know the mask intervention may slow the spread speed by a small factor, but were we to measure over a year (or even longer) we might observe the same total number of infections: the virus is going to infect everyone susceptible, only at a slightly slower pace.
2. Only a portion of the people were even wearing masks. A few people wore masks and the risk of infection dropped by a few percent. Declaring masks don't work because a couple people wore them yet the entire population didn't see a complete decline in infection is illogical and dishonest.
3. The study not being able to conclude in a statistically significant way that cloth masks prevent infection is completely different from concluding that cloth masks are worthless. Your aversion to masks is completely a reflection of your bias and not supported by this study.
...there were 54,000 people in the cloth mask villages, and 106,000 people in the surgical mask villages. Compliance was over 40%.
That's more than "a few people".
I'm telling you the conclusions of the paper. Your faith in masks is an entirely separate question that is clearly unaffected by the data here, because it requires proving a negative.
Is it possible that cloth masks actually work, and this huge study failed to find any significant effect? Anything is possible, but the results here are indistinguishable from noise, and don't support the claim. And with every RCT that gets published showing negligible effect from community masking, the probability that the claim is true gets smaller.
Oxygen is smaller and easier to pass the filters than COVID-19 particles. It's possible not to have reduced oxygen flow but protect against the virus, but physically impossible to do the reverse as you suggest.
For fun, I just googled 'N95 reduced oxygen flow' and found this pearl from Stanford as the top result: https://digitalmedic.stanford.edu/myth/myth-face-masks-can-r...
> Myth: Face masks can reduce oxygen getting to the lungs and bloodstream
> ... Some masks mean you have to put more effort into breathing if you wear them for a long time.
> ... If worn for many hours without a break, an N95 mask might potentially affect oxygen levels but likely not to a dangerous extent, especially in people who are healthy.
'put more effort into breathing' aka 'suffocating at normal breath patterns'. Oh, and it actually does reduce the oxygen levels, but rest assured citizen, it is nothing to worry about. It's just a myth. There is a word I'm looking for here, miss, misty, aha, misinformation.
Personally, I don't consider that reduced airflow relevant to me or anyone I know. The people with reduced lung capacity do complain about having trouble after 15 minutes, but continue to wear them. In fact, people with reduced lung function are the most aggressive mask wearers I know.
Now consider that kids are forced to wear cloth masks all day long, day after day after day. This is a choice, there are places in the world where they are just as serious about covid as US, and yet kids can stay in class without masks.
It's a rough tradeoff. I wish we could have an adult conversation, not pretend there are no minuses and masks are a no brainer in all situations. We have replaced conversation with Twitter sloganeering.
An example: https://nltimes.nl/2021/08/23/school-year-starts-north-nethe...
> In secondary education, teachers and pupils who have been fully vaccinated for at least two weeks won't have to quarantine after contact with someone who has the coronavirus. Only unvaccinated teachers and -students need to take a self-test twice a week. Teachers and students need to maintain social distancing, and face masks are mandatory in corridors and canteens.
> In primary education, adults like teachers and parents must keep 1.5 meters apart. But for the kids, no restrictions apply other than the general rules like washing your hands regularly and staying home if you have symptoms.
Why on earth wouldn't I? My O2 levels don't seem to be too degraded by a mask. And, even if they were, I would never expect to be hired by people who saw me put them at risk. I'm not sure I would feel comfortable accepting a job from people who would hire someone who wasn't willing to wear a mask.
> I wish we could have an adult conversation, not pretend there are no minuses and masks are a no brainer in all situations.
I've never experienced a negative from wearing a mask. Some people are really opposed by I just don't get it. It makes as much sense to me as people not wearing a seat belt because they worry about chaffing.
> there are places in the world where they are just as serious about covid as US, and yet kids can stay in class without masks.
Every state that lets kids run around without masks produces news stories about COVID spreading like wildfire through the schools. I don't know why I would consider that acceptable. Kids should not be forced to get COVID for no reason.
Then why are Nature reporting on them in such conclusive language?
If there is any Russian speaker around, would be instructive to take one of the old top Soviet science publications and translate the TOC.
> Then why are Nature reporting on them in such conclusive language?
Given Nature has very well-regarded peer reviewers, it seems likely that this is an earlier report on something they expect to publish as peer reviewed. Why report it now? Because people are dying and this could help them.
Are they arguing over comma locations? Waiting until the next publication date? Who knows.
The study found an effect size of zero in the cloth mask cohort, and an 11% difference in the surgical mask cohort. Effect sizes that managed significance were just barely significant, at a p-value of 0.043. Also, the researchers didn't do any baseline serology, so it's quite difficult to know if there was a starting bias influencing the final results. It's also difficult to know the degree to which the non-blinded nature of the study and voluntary seroprevalence testing biased the outcome. At such small effect sizes, questions like these matter a great deal.
Nevertheless, it is encouraging that someone actually bothered to do a proper RCT of masking as "protection for others", and this study has several points that should be widely communicated (e.g. the ineffectiveness of cloth masks). However, I would not say that "masks passed their test" is really one of them...these results are pretty mediocre.
Vinay Prasad of UCSF has made an excellent summary of the results of the Bangladesh RCT, and I recommend it strongly:
https://twitter.com/VPrasadMDMPH/status/1435679462142607361