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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

#251

Post by asabjorn »

lostlogin wrote: post #192
xkcd-sucks wrote: post #165

Earlier quoted context omitted.

I wear "n95" masks while sanding drywall, obviously trying to make the fit as good as possible, and still my boogers end up with tons of plaster in them. I would assume these particles to be bigger than any virion.

When wearing a mask in a hospital setting I had to have a fitting done. A test was run and a machine measured particles getting through. Properly fitted, nothing got though down to a very small size (which I don't recall). An earlier version of the test saw some particle released into the room and a properly fitted mask wouldn't let it though. If people could smell the chemical, the fit was poor.

And I assume you were also trained in how to use the masks properly so that they didn't increase chance of virus spread and only used N95 masks? E.g. don't touch mask and dispose/clean the mask after each use.

Almost nobody does this, and many use cloth masks.

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

#252

Post by asabjorn »

wrycoder wrote: post #115
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…

I suspect that in locations with a higher prevalence of masking the population is generally more vigilant: more hand washing, more social distance, stay at home when ill, avoid obviously ill people, and so on. May be a case of correlation, not causation. It would be interesting to have a trial where everyone was wearing N95s, but we're not likely to see that.

> I suspect that in locations with a higher prevalence of masking the population is generally more vigilant: more hand washing, more social distance, stay at home when ill, avoid obviously ill people, and so on. May be a case of correlation, not causation.

The states with the highest mask use (NYC, CA) has some of the highest covid positive rates, so the data does not seem to back up your assertion.

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

#253

Post by asabjorn »

sschueller wrote: post #17

N95/FFP2 seem to be very effective. I wish the media and government would have spent more time in educating people in things like how N95 masks work and that it isn't like a coffee filter. Even thought the pores are larger than a virus the masks are statically charged causes smaller things to get trapped. Many people don't know this but probably had an interaction with static electricity sometime in school and would…

> N95/FFP2 seem to be very effective.

Why does then the states with the highest mask use (CA, NYC) have much higher covid positive rates than states with some of the lowest mask use (Florida, NYC)?

> Education is key to understanding. You can't reach everyone most.

N95 masks improperly used will hold covid for 24hrs and spread them by the incessant touching most people do of their masks before they touch other things.

Education only works if the means as deployed are likely to have a positive effect, such as surgeons in a strict hospital settings (where they are still used the wrong way as most people still touch the mask).

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

#254

Post by dragonwriter »

nostrebored wrote: post #162
omginternets wrote: post #93

Earlier quoted context omitted.

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.

Counterpoint: Miami

Miami-Dade County, FL has a little under half the cumulative confirmed cases as Los Angeles County, CA (500K vs. 1.2M) with a little over a quarter the population (2.7M vs. 10M), for a much higher per capita rate. So...how is it a counterpoint?

(Case numbers from usafacts.org.)

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

#255

Post by froh »

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…

super spreaders and super spreader events are key to transmission, like indoor singing hallelujah or indoor family gatherings happy birthday granny or schooling, Kindergarden, you get the gist...

indoor and speaking/singing is the key combination for aerosol based transmission.

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

#256

Post by dragonwriter »

asabjorn wrote: post #245
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…

> The rationale for cheap masks is that they drastically reduce the spread of particles from the wearer to everyone else nearby. If so, why does states with the highest mask use (CA, NYC) have much higher covid rates than states with some of the lowest mask use (Florida, Texas)?

> If so, why does states with the highest mask use (CA, NYC) have much higher covid rates than states with some of the lowest mask use (Florida, Texas)?

They...don’t (leaving out NYC because the other three things are large, diverse states and NYC is a single large city):

California 3.7M cumulative cases & 1,336 case/day current 7-day average vs. 39.5M population

Florida 2.3M cumulative cases & 3,007 case/day 7-day average vs 21.5M population.

Texas 2.9M cumulative case & 2,034 case/day current 7-day average vs. 29M population.

FL and TX are worse on per capita cumulative cases, and much worse on current per capita new cases than California.

(case numbers from usafacts.org)

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

#257

Post by j4yav »

crocodiletears wrote: post #187
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?

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.

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

#258

Post by wyclif »

crocodiletears wrote: post #187
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?

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…

I think the CDC mis-messaging is one component of this. Another is that there is no long tradition of public medical mask-wearing in the West, unlike many parts of SE Asia. Public mask-wearing is new, exceptional, and somewhat alarming if you live in North America or Europe.

Yet another component is that trust in the press and other public institutions was at possibly an all-time low in America at the time the COVID pandemic became public knowledge, and shows no signs of pulling out of that nosedive.

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

#259

Post by vondro »

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.

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

#260

Post by slver »

alvah wrote: post #237
slver wrote: post #189

Earlier quoted context omitted.

Why on Earth are you calling them “propaganda” videos, when China was trying to downplay the pandemic at the time? See, this is one big reason we’re collectively dumb. Everyone and their big conspiracy theories.

There hasn't been a single case reported in the West, of anyone dying instantly in the street of COVID-19. Ergo, videos filmed within China, allowed by the authorities to be viewed outside China, purporting to show this scenario, are the very definition of propaganda.

We also saw videos of sick people left to die in Chinese hospitals from their own phone recordings. Is that also propaganda?

And no, a video of something that isn’t what we thought it is, is not the definition of propaganda. Propaganda has a goal.

This video doesn’t match a single goal China has. If it does name it.

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