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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

#151

Post by mdp2021 »

nradov wrote: post #139
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…

Maintaining the recommended level of physical activity cuts COVID-19 death risk by 4× compared to being sedentary. https://bjsm.bmj.com/content/early/2021/07/21/bjsports-2021-... And before anyone claims that it's just a correlation, please read the whole paper. The authors did a good job of establishing causality.

> cuts COVID-19 death risk by 4×

And halved severe illness.

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

#152

Post by vondur »

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…

Am I misunderstanding this from the paper: "The proportion of individuals with COVID-like symptoms was 7.62% (N=13,273) in the intervention arm and 8.62% (N=13,893)" That really seems like a pretty small overall difference in the two groups in terms of those getting infected.

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

#153

Post by slg »

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…

>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

Isn't this dependent on the assumption that the risks are reduced uniformly across society? Lockdowns/quarantines are the obvious counterexample. Someone going into complete lockdown reduces their risk to practically zero. However a small group of people doing that won't have much effect on the societal numbers. Therefore the societal reduction is much less than the individual reduction until that R value drops low enough.

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

#154

Post by mdp2021 »

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 is not "masks → -11%" as you seem to be reading it: it's -11% after a +30% compliance.

More compliance, much increased results than that 11%.

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

#155

Post by aw1621107 »

starik36 wrote: post #101
aw1621107 wrote: post #69

Earlier quoted context omitted.

Not quite. The wording has to be parsed carefully: > Those living in villages randomly assigned to a series of interventions promoting the use of surgical masks were about 11% less likely than those living in control villages to develop COVID-19 So it's not mask vs. maskless; it's promotion of masks vs. no such promotion. The study [0] gives more information: > In villages that received the intervention, mask use inc…

I missed the use of word "promotion". It would be interesting to see the difference in just use of the masks.

> It would be interesting to see the difference in just use of the masks.

Indeed it would, but I think getting a large-scale trial with a sufficiently high compliance rate would be a challenge, to say the least.

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

#156

Post by jasonlaramburu »

packetlost wrote: post #137
jasonlaramburu wrote: post #130

Earlier quoted context omitted.

Maybe lower mask adherence among younger people or different behaviors-- older people in villages might stay at home more.

if the latter is true, then wouldn't that be an indicator that masks do not, in fact, work as well as thought?

It could, or it could mean that the protective effect of surgical masks is most pronounced indoors.

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

#157

Post by helge9210 »

jasonlaramburu wrote: post #131
polote wrote: post #127

Earlier quoted context omitted.

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

Anyone who is legitimately concerned about COVID transmission should be wearing at least a KN95 mask. It would be interesting if the study had compared effectiveness against higher performance masks and respirators.

I totally agree.

On the other hand I would like to opt out of this exercise, since I'm totally not concerned with COVID.

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

#158

Post by RHSeeger »

nivenkos wrote: post #71
bsksi wrote: post #56

Earlier quoted context omitted.

In my country you are removed and fined if you are seen indoors or outdoors where you can't keep a distance without a mask. It's when I read comments like yours that I feel so jealous of the US. You don't even know what living where I am is like. For you it's like a place that couldn't possibly exist. :P

> It's when I read comments like yours that I feel so jealous of the US. And then the same Americans ban you from Reddit if you complain about the lockdowns or forced mask mandates.

1. The people that are in charge of making such decisions (scientists, politicians, etc) said you should (and in some cases must) wear a mask. They said that doing so is more for the protections of others, but it also helps the wearer.

2. The impact of wearing a mask, with the exception of a small subset of people, is negligible. At most, it's very slightly uncomfortable.

Given those two things, choosing _not_ to wear a mask makes you a bad person in the eyes of most people; and rightfully so. You are unwilling to put forth a minimal effort to help protect those around you.

And yes, if everyone sees you as a bad person because of your chosen actions, then you can expect to shun/comdemn/avoid you. That's how society works across the world.

Now that this study has come out, with actual numbers, hopefully the recommendations will change; or at least it will spur some research to try to confirm the lack of protection provided by cloth masks. Recommendations were made based on existing information. New information is added and recommendations/actions are taken based on that. That's how science is _supposed_ to work.

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

#159

Post by betwixthewires »

learc83 wrote: post #97
betwixthewires wrote: post #60

Earlier quoted context omitted.

It's a pretty solid gotcha.

It's a terrible gotcha. It's only effective on people who already agree with you. Imagine a town council meeting where someone is proposing a $25 fine for crapping on the sidewalk. And a libertarian pops and screaming "You're saying you want to use violence up to and including murder to keep our sidewalks clean!" Again technically there is a hypothetical chain of causality from sidewalk crapping fine to bodily harm/m…

Well it's not saying "nothing should be enforced ever because all enforcement is backed by violence", it is just acknowledging the reality of it and then determining if a particular rule justifies that, and then farther down, if a rule enforced by violence is unjust, determining whether the enforcing party is an enemy or not.

Generally libertarians only allow for rules against behaviors that violate the rights of others because of this, and I think that's about right.

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

#160

Post by nradov »

hadlock wrote: post #141
nradov wrote: post #63

Earlier quoted context omitted.

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.

The Delta variant is more contagious so there is a higher rate of infections, but it's not a completely different virus. Symptoms in children are no more severe than with earlier variants.

"Among all hospitalized children and adolescents with COVID-19, the proportions with indicators of severe disease (such as intensive care unit [ICU] admission) after the Delta variant became predominant (June 20–July 31, 2021) were similar to those earlier in the pandemic (March 1, 2020–June 19, 2021)."

https://www.cdc.gov/mmwr/volumes/70/wr/mm7036e2.htm

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