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Surgical masks reduce Covid-19 spread, large-scale Stanford study shows

med.stanford.edu

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Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows

#141

Post by hadlock »

nradov wrote: post #63
GeekyBear wrote: post #36

Cloth masks are quite effective against viruses with a droplet based spread. Widespread mask use came as close to wiping out last year's Flu season as we've ever seen. >Amid COVID-19 pandemic, flu has disappeared in the US NEW YORK (AP) — February is usually the peak of flu season, with doctors’ offices and hospitals packed with suffering patients. But not this year. Nationally, “this is the lowest flu season we’ve h…

The science on mask mandates for young school children is unclear. Most European countries don't require it. https://nymag.com/intelligencer/2021/08/the-science-of-maski...

As far as schools are concerned, Delta is a completely different virus. Outbreaks appear to be much more common in the US this fall with Delta, compared to this spring before Delta became the dominant strain. It's difficult to make long term comparisons and draw definitive conclusions when the mutations are great between semesters.

Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows

#142

Post by mdp2021 »

bgorman wrote: post #111

The problem with this mask business is it treats masks as the only variable. The United States is incredibly unhealthy and most people do not get enough exercise or spend enough time outdoors. It would not surprise me if governments would obtain better results by telling citizens to exercise regularly and eat healthy. Instead it seems like governments are doubling down on a strategy on scaring/bullying out of shape c…

No, the study is about a ~11% decrease of infections after a ~30% increase of mask use after an awareness campaign.

> masks for outdoor exercise

I really hope that is for the jogging in the market area of Delhi (I hope this was at least in urban areas).

Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows

#143

Post by worker767424 »

slg wrote: post #81
timr wrote: post #67

Earlier quoted context omitted.

They did all of those things, but this paper is about the effect of mask-wearing (surgical vs. cloth vs. none) on the rate of symptomatic seroprevalence in the groups. Kuldorff is right, and is just stating the top-line numbers from the paper.

>Free mask distribution and promotion reduced the proportion of people who reported COVID-like symptoms on average by 11 percent, which was driven mainly by the effects of surgical masks. Villages where cloth masks were distributed experienced a 5 percent reduction in symptoms, while villages where surgical masks were distributed saw a reduction of 12 percent. About a third (40 percent) of those who reported COVID-19…

And at 9%, some of that is likely seeing trusted public figures essentially saying "it's not safe out there" by talking about masks, and people restricting their actions accordingly. It's really hard to actually test this.

Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows

#144

Post by nradov »

bendbro wrote: post #78

Does the paper reveal the seroprevalence by control village and intervention village? I just scanned it and can find no such information. EDIT: Table A14 is the closest I can find but it is only coefficients, not the underlying counts.

This study didn't perform seroprevalence sampling.

Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows

#145

Post by Jabbles »

polote wrote: post #127
ch4s3 wrote: post #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 like…

At the end of the day if the reduction is 11%, even if that works (because that reduce by 11%) that is still useless in order to control the epidemic. Unless we find 10 measures like that. But what they show is probably not the same that the impact of mask mandate or an `always wear mask` at the personal level. So not much is applicable about that study. Only that mask kind of reduce covid spread

social distancing, handwashing, increased ventilation, wfh, contact tracing app, venue contact tracing, vaccines, rapid testing, temperature checking

No idea if they're all ~10% effective, nor if you can just add percentages up like that... but it's not hard to list measures we can take, both individually and as a society.

Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows

#146

Post by schroeding »

nielsbot wrote: post #24
dragontamer wrote: post #18

Earlier quoted context omitted.

I think most of us got cloth masks with the full expectation that they were worse than proper PPE from hospitals (be it surgical masks or N95 masks). I'm not sure if people remember: but there was a shortage of masks of all kinds in March 2020. Cloth masks were the only thing we could get, and we all knew they were kind of crap (a lot of us were using coffee filters stapled onto the masks to increase its effectivenes…

Seems quite reasonable to wear a (K)N95 instead of a surgical mask. Slightly less comfortable, but yes, affordable for most.

"Slightly", I'm not so sure about that :-D

Where I live, N95 masks are mandatory in public transport since February, and it's really uncomfortable to be in an non-airconditioned metro car which is full to the brim, with water running down the windows from condensation. That's totally acceptable with surgical masks, but there's a face melting heat under any N95 mask in this condition :-D

Of course I wear them as mandated, but I really hope we can switch back to the more practical surgical masks soon, with enough vaccinations :-)

(Or that there is an early onset of winter :-D)

Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows

#147

Post by jacquesm »

polote wrote: post #127
ch4s3 wrote: post #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 like…

At the end of the day if the reduction is 11%, even if that works (because that reduce by 11%) that is still useless in order to control the epidemic. Unless we find 10 measures like that. But what they show is probably not the same that the impact of mask mandate or an `always wear mask` at the personal level. So not much is applicable about that study. Only that mask kind of reduce covid spread

You are making a number of pretty common errors: no anti-viral measure is going to be perfect, it is always going to be a layercake and an 11% improvement can make a huge difference because for one it might tip the balance from 1.05 to 0.95 which is the difference between a spreading disease and one that is on the return and because these percentages are multiplicative, not additive, so it would not take '10 measures like that'.

Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows

#148

Post by daveguy »

polote wrote: post #127
ch4s3 wrote: post #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 like…

At the end of the day if the reduction is 11%, even if that works (because that reduce by 11%) that is still useless in order to control the epidemic. Unless we find 10 measures like that. But what they show is probably not the same that the impact of mask mandate or an `always wear mask` at the personal level. So not much is applicable about that study. Only that mask kind of reduce covid spread

It doesn't take 100% control to make a significant impact. Every % you take off of transmission is significant because the relationship between transmission and cases is exponential.

Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows

#149

Post by em500 »

nradov wrote: post #63
GeekyBear wrote: post #36

Cloth masks are quite effective against viruses with a droplet based spread. Widespread mask use came as close to wiping out last year's Flu season as we've ever seen. >Amid COVID-19 pandemic, flu has disappeared in the US NEW YORK (AP) — February is usually the peak of flu season, with doctors’ offices and hospitals packed with suffering patients. But not this year. Nationally, “this is the lowest flu season we’ve h…

The science on mask mandates for young school children is unclear. Most European countries don't require it. https://nymag.com/intelligencer/2021/08/the-science-of-maski...

The Netherlands had fully opened elementary schools since February, UK since March, without any masking and related drama and with barely any distancing. Child Covid-19 mortality has remained very low throughout, even with Delta (grand total of 7 deaths in the UK in the last 6 month).

All the drama around masking at schools seems largely an American phenomenon, where it looks like it's just another flag to signal if you're in Team Red or Team Blue.

Re: Surgical masks reduce Covid-19 spread, large-scale Stanford study shows

#150

Post by gunapologist99 »

kragen wrote: post #104
slg wrote: post #16

Earlier quoted context omitted.

>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.

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…

> 4636 deaths in PRC

That number is completely laughable. It's literally communist propaganda.

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