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Face masks effectively limit the probability of SARS-CoV-2 transmission

science.sciencemag.org

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Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#301

Post by cr1895 »

irq11 wrote: post #246
oasisbob wrote: post #145

Earlier quoted context omitted.

Here is a recent published review for those seeking a more comprehensive and complete evaluation of the literature: Howard, Jeremy, et al. "An evidence review of face masks against COVID-19." Proceedings of the National Academy of Sciences 118.4 (2021). https://www.pnas.org/content/118/4/e2014564118

That is a joke of a “review”, and should never have been published. Consider that it doesn’t mention the only randomized controlled trial of masks and Covid ever performed (it showed no significant protective effect), which was conducted during the period the “review” was being compiled: https://www.acpjournals.org/doi/10.7326/m20-6817 There’s simply no excuse. the authors cherry-pick and misinterpret top-line data t…

You should note well that the study you point out made no assessment of whether mask wearing reduced the risk of spread from the mask wearer to others, which is a key point of the utility of mask-wearing during this pandemic.

It is very deceptive for you to claim that this is the only trial of “masks and COVID” when you omit that nuance.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#302

Post by perryizgr8 »

astrange wrote: post #298
perryizgr8 wrote: post #239

Earlier quoted context omitted.

> then the cheap mask help a lot when people wear them. Are there any reliable and conclusive studies supporting this?

There are not even any reliable studies showing that surgical masks help during surgery. The problem with public health agencies is that, apparently, if they don't have an RCT they immediately jump to make the worst possible decisions. So try not to do the same thing.

> There are not even any reliable studies showing that surgical masks help during surgery.

That's fine, because I am not a surgeon and I don't care.

I do care about fogging up my glasses and having to speak up without any proper evidence that wearing a mask helps significantly against covid.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#303

Post by astrange »

mulmen wrote: post #72
mhb wrote: post #60

Earlier quoted context omitted.

I don't think people need to know how they work. They just need to know that those are what doctors wear and that they are very, very effective. And much better than a mask you make from ad hoc materials. Once N95 masks became readily available and cheap, it was (and is) mysterious why people weren't being told to wear them to protect themselves instead of wearing whatever was at hand to sort of protect themselves an…

If you tell me how something works and it fits within my mental model of the world then I will trust you. I will add this information to my mental model of the world. If you tell me something works but can't explain how I will consider if the claim is worth evaluating then attempt to understand it myself before accepting it. If you tell me to trust you with no explanation I will immediately distrust you.

When Semmelweiss invented handwashing, all the other doctors ignored him because they didn't like his model, even though he had empirical evidence.

Similarly, people like to argue against things like the minimum wage because it doesn't fit some economic model, but they don't realize those models are made up post-hoc to fit older real world data that turned out to be biased and incomplete.

Oh, and the West had to deal with scurvy for hundreds of years after discovering the cure (lemon juice) because we'd invented the food poisoning and germ theories of diseases and so we refused to believe you could cure one with food.

So don't worry too much about modeling things.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#304

Post by adrianb »

vondro wrote: post #259

In Japan, people that are sick wear masks, voluntarily, not to spread the infection. Well, that was my observation travelling Japan, anyway. I was amazed by it, and as the pandemic started last year, I had hopes that this thoughtful behavior will become a norm in my area too (central Europe). Unfortunately, it seems that will not be the case. Masks are universally hated.

Wearing masks when sick is a good hygiene practice in general. But in COVID context with significant asymptomatic spread it won't help as much as it does for colds and flu.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#305

Post by henrikschroder »

andreygrehov wrote: post #155
rsj_hn wrote: post #75

Earlier quoted context omitted.

Indeed this is the money paragraph: "The effectiveness of masks, however, is still under debate. Compared to N95/FFP2 respirators which have very low particle penetration rates (around ~5%), surgical and similar masks exhibit higher and more variable penetration rates (around ~30-70%) (2, 3). Given the large number of particles emitted upon respiration and especially upon sneezing or coughing (4), the number of respi…

> observational data show that regions or facilities with a higher percentage of the population wearing masks have better control of the coronavirus disease Which is also not entirely true. There are quite a lot of regions (data from worldometer, statista) that have a better control of the virus despite people not giving a crap about face masks. For instance, Florida has 1600 deaths/M vs 3000 deaths/M in New Jersey.…

I think it's hilarious that everyone who commented on this completely ignored your given examples of Florida and New Jersey, and instead chose to compare Florida to completely different places, that just-so happen to make Florida look bad.

Regardless of strategy, every country in the northern hemisphere that had a decent number of cases in spring 2020, got absolutely hammered in winter 2020.

Of course there are examples of regions where the one with more restrictions got a better result than the one with less. But there are simply way too many counter-examples where regions that did more, tried more, had more restrictions, still got a similar or worse outcome than comparable regions that didn't.

Here's a pretty fun quiz that highlights this complete lack of correlations in the actual data: https://www.covidchartsquiz.com/

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#306

Post by astrange »

omginternets wrote: post #93
vondur wrote: post #88

I don't know. We had some of the highest mask wearing percentages in the country here in Southern California, yet some of the highest infection rates in the world. Something isn't adding up here. I'm guessing if everyone had N95 masks, we would have seen lower numbers however. I don't think the average cloth masks that people are wearing are very effective.

Could it have to do with population density (perhaps even only in certain areas)? My reasoning is that you could have high transmission among the minority that doesn't wear masks, and that might suffice to make the absolute case-load quite high.

In NYC the less dense areas had worse infections.

The problem in California might be crowding, ie it's not designed for the population density and so everyone has roommates or lives with an extended family. That would cause more indoor transmission, and I believe a lot of cases in CA were among working class people and Latinos.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#307

Post by oldgradstudent »

mike_hearn wrote: post #280
irq11 wrote: post #236

Earlier quoted context omitted.

That is not “very much yes”, that is “an anecdote suggests yes”. The statistical illiteracy here is astounding from professional scientists. ”0% of ths sick passengers wore masks, compared to 47% of the healthy passengers. Another way to look at that is that 0% of the mask wearers got sick, but 35% of non-wearers did” And another way to look at it is that 65% of non-wearers didn’t get sick. The group of sick people i…

Error bars would be nice. They're MIA in large swathes of COVID related research. I've read a lot of COVID papers in the past year and this paper is typical of the field. Things you should expect to see when reading epidemiology literature: 1. Statistical uncertainty is normally ignored. They can and will tell politicians to adopt major policy changes on the back of a single dataset with 20 people in it. In the rare…

It gets worse.

You should look at the the observational studies measuring vaccine effectiveness in Israel coming from Balicer and his group.

They report the effect of the vaccine on number of positive cases without even mentioning that the vaccinated individuals are not routinely tested by ministry of health policy, or that the main reason people get tested is to shorten the isolation period after contact with covid-19 cases, which vaccinated individuals are exempt from.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#308

Post by astrange »

thewizardofaus wrote: post #16

Have any studies been completed yet on immune system efficiency/suppression after covid restrictions (masks, hand sanitizer etc) ? In Australia we were very lucky with the COVID situation. And purely annecdotal, but I know many people who haven't been sick at all during the pandemic. But as we approach winter here and perhaps no longer hand sanitize appropriately, many of these people are becoming "the most unwell [t…

I don't think it works that way. Your kids might develop some new allergies if you sanitize them too much, but just rub some dirt on your face or eat sauerkraut or something, it'll work out.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#309

Post by astrange »

perryizgr8 wrote: post #302
astrange wrote: post #298

Earlier quoted context omitted.

There are not even any reliable studies showing that surgical masks help during surgery. The problem with public health agencies is that, apparently, if they don't have an RCT they immediately jump to make the worst possible decisions. So try not to do the same thing.

> There are not even any reliable studies showing that surgical masks help during surgery. That's fine, because I am not a surgeon and I don't care. I do care about fogging up my glasses and having to speak up without any proper evidence that wearing a mask helps significantly against covid.

The kind with a bendable bar or tape at the top for your nose don't affect my glasses.

Anyway, you're going to run into the same problem doctors' advice has, where everything not required is forbidden. If a 100-year problem like a pandemic comes up, try some unproven precautions, it's better than not doing anything until it's mandated.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#310

Post by piva00 »

j4yav wrote: post #257
crocodiletears wrote: post #187

Earlier quoted context omitted.

In the US, it's more to do with the way the CDC's messaging throughout the pandemic than any rejection of the evidence concerning a mask's efficacy. People refusing to wear masks rarely question whether or not it works, and more to do with a low estimation of the disease's threat, as well as contempt for both the technocrats who chose to mislead the public about masks early on, and leaders who they believe are overst…

Wasn’t it more a result of tribalism? Even before the masks were really a topic it became quite important politically for the pandemic to be real or not, depending on which group you hoped benefitted politically or not. From the outside it looked like everything more or less flowed from that starting point, and then everyone picked their positions and favorite realities from there.

No. And I say that due to my experience here in Sweden, with the same message spread around about masks. I understand why the government did it in the beginning of the pandemic, to save PPE from shortages, to avoid people using masks and getting a false sense of security, etc.

Still, it created a lot of distrust when the message changed a few months ago, it wasn't a tribalist issue and I can completely understand how people ended up with this distrust. They are still wrong and I completely agree with this comment [1].

[1] https://news.ycombinator.com/item?id=27231688

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