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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

#291

Post by rcxdude »

jasonlaramburu wrote: post #148
function_seven wrote: post #113

Earlier quoted context omitted.

> On the other hand, "observational data show that regions or facilities with a higher percentage of the population wearing masks have better control of the coronavirus disease 2019 (COVID-19) (7–9)." So how to explain these contrasting results and apparent inconsistencies? My hypothesis regarding surgical mask prevalence and how it correlates with better virus control: People who wear masks--however effective they m…

It’s worth also considering the case of ski helmets. Since these have became common on the slopes head trauma has actually increased because wearers take more risks.

This is not clear cut: see this review which concludes that this is not the case (helmets neither increase injuries nor risky behaviour). In general the idea of risk compensation is frequently brought up in these cases, and while it may seem intuitive, it usually does not appear in the data.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3989528/

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

#292

Post by darick »

himinlomax wrote: post #286
hermitcrab wrote: post #263

Earlier quoted context omitted.

If you wore a mask in public in the UK before COVID, you would have got some very strange looks. They might have thought you were a criminal trying to hide your face. It seems fairly normal now though.

It's worse than that, you'd probably had been harassed by the police, or just simply arrested.

Don't agree that that's the case at all if you wore a mask on a packed tube commute for example.

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

#293

Post by johbjo »

solarengineer wrote: post #176
mattm wrote: post #153

Earlier quoted context omitted.

"Some people with swine flu travelled on a plane from New York to China, and many fellow passengers got infected. Some researchers looked at whether passengers who wore masks throughout the flight stayed healthier. The answer was very much yes. They were able to track down 9 people who got sick on the flight and 32 who didn’t. 0% of the sick passengers wore masks, compared to 47% of the healthy passengers. Another wa…

What is astounding to a lot of us in South East Asia is the reluctance of the West in learning from our lessons. How many deaths and personal trauma experiences do people in general need to go through in order to learn from others?

> What is astounding to a lot of us in South East Asia is the reluctance of the West in learning from our lessons.

Agreed. We should have relocated Britain and NYC to the equator long time ago.

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

#294

Post by cr1895 »

awb wrote: post #202
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.

I wonder how much super spreaders affect outbreaks. Let’s say LA had 50 super spreaders vs. 25 in SF. I’d expect LA to have more than 2x the cases because of the exponential spread of the virus. And I think the idea behind masks was not that they’re a cure, but a 2nd best option if the best option of social distancing isn’t possible. And even if they’re 30% effective, the idea is to get R (the number of subsequent pe…

Zeynep Tufecki described this phenomenon in the Atlantic, going into its overdispersed nature of spreading and how most infections don’t result in a spread to others, but some circumstances become super-spreading events with an outsize impact:

https://www.theatlantic.com/health/archive/2020/09/k-overloo...

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

#295

Post by astrange »

Gibbon1 wrote: post #240
solarengineer wrote: post #176

Earlier quoted context omitted.

What is astounding to a lot of us in South East Asia is the reluctance of the West in learning from our lessons. How many deaths and personal trauma experiences do people in general need to go through in order to learn from others?

Friends were talking about that a year ago. Health authorities in the west were completely ignoring their counterparts in Asia early on. Dismissed the threat until the pandemic blew up in Northern Italy and New York. A lot of people in HN were arguing that the 0.7% fatality rate reported by Chinese authorities in Feb/20 was because Chinese medical care is bad. Casual racism is kinda pernicious.

If you watched reddit all the comments to all news from China (including doctors dying, doctors not dying, hospitals being built or filling up, doctors clapping on TikTok because they'd released their last patients) was complaining about it and calling it fake news from the CCP. They were happy about the same thing from the US though.

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

#296

Post by astrange »

kelnos wrote: post #268
jasonlaramburu wrote: post #148

Earlier quoted context omitted.

It’s worth also considering the case of ski helmets. Since these have became common on the slopes head trauma has actually increased because wearers take more risks.

Or is it that people are taking the same amount of risks, but accidents that used to cause death are now "merely" causing head trauma? (I don't know either way, just curious to know if this angle has been investigated.)

This is probably more likely. Risk compensation (people behaving more dangerously when they have more safeguards) basically doesn't happen - it's an excuse to not use the safeguards. When seatbelts were introduced lots of people were opposed because it encouraged driving, or because they wanted the chance to just roll out of the car if it was about to crash.

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

#297

Post by astrange »

nradov wrote: post #238
panarky wrote: post #229

Earlier quoted context omitted.

> no convincing evidence This MIT study [0] was pretty convincing. They conclude that "face masks can be an extremely effective indoor safety measure". For example: If an infected person was riding on a commercial airline with 100 other people, other passengers would be at risk of infection within 70 minutes. If all of the passengers wore masks, however, that space could be safe for up to 54 hours. [0] https://www.pn…

How can a model be convincing if it hasn't been extensively tested in the real world?

The model of wearing masks has been extensively tested in Asia. Meanwhile US doctors were telling me that putting on a mask would actually cause you to get infected faster because you'd do it wrong. (Then the CDC announced mask orders the next day and they mumbled something about new evidence to me.)

And we can see who's done better in the last year.

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

#298

Post by astrange »

perryizgr8 wrote: post #239
panarky wrote: post #135

Earlier quoted context omitted.

> The effectiveness of masks, however, is still under debate Effective for the mask wearer, or effective for others in the vicinity of the mask wearer? It's well established that cheap cloth masks and procedure masks don't protect the mask wearer very much. The rationale for cheap masks is that they drastically reduce the spread of particles from the wearer to everyone else nearby . If your goal is to protect yoursel…

> 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.

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

#299

Post by astrange »

greggman3 wrote: post #278
logicchains wrote: post #214

Earlier quoted context omitted.

>Compare your example to an area where people really take masking serious, such as Hong Kong, and then maybe you'll have a valid comparison. It's not fair to compare the US/Canada with East Asian countries like Hong Kong because the biggest contributor to covid fatality rates apart from population age is obesity rates, which are way lower in East Asia.

I haven't clue about statics so it's likely this is wrong but a quick graph of COVID deaths per million vs obesity rate for each country doesn't look like there is any correlation. https://jsgist.org/?src=7b456a001284587cb90c7693ac0e6f3b Also, if age is the #1 factor then Japan should have the worst covid as they have the most old people per capita but they don't. They also haven't locked down but they have worn mask…

Japan is kind-of locked down, mostly by canceling large events and keeping people home. They're working on the principle that covid has mainly aerosol transmission and is spread by rare superspreaders rather than just everyone.

It's working okay but not as well as Korea.

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

#300

Post by apatters »

tgsovlerkhgsel wrote: post #39

This entire study seems to be centered around a theoretical, mathematical model, and I didn't see any attempt to actually validate that model. Basically, the authors seem to assume that the virus behaves according to their formulas, and show that under their assumptions, face masks work, but don't actually prove that their assumptions match reality - or did I miss something?

My thinking has always been that of all the possible interventions to reduce viral spread, something like making people wear masks while grocery shopping has almost no negative side effects. Whereas closing the grocery store altogether has major negative side effects, like lost jobs and people not being able to buy groceries.

So I think the evidential bar for requiring masks should be pretty low (unless it is a special case, like making people wear masks when they're exercising likely has larger negative side effects). Who cares if it may not do much? The cost of doing it is so low.

Whereas the evidential bar for policies that do more collateral damage ought to be higher.

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