[HN Gopher] Face masks effectively limit the probability of SARS...
___________________________________________________________________
Face masks effectively limit the probability of SARS-CoV-2
transmission
Author : paultgriffiths
Score : 133 points
Date : 2021-05-20 20:27 UTC (2 hours ago)
(HTM) web link (science.sciencemag.org)
(TXT) w3m dump (science.sciencemag.org)
| thewizardofaus wrote:
| 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 [they] have been in years".
| deepserket wrote:
| protip: shower once a month to train your immune system during
| lockdown
| sschueller wrote:
| 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 understand it if someone explained it. Instead people get
| put in a bucket and no dialog is possible.
|
| Education is key to understanding. You can't reach everyone most.
| matz1 wrote:
| The problem is wearing mask is annoying and uncomfortable. If I
| have to choose, I'll choose the increased risk of covid all the
| time rather than wearing mask.
| petertodd wrote:
| A big part of why they are annoying and uncomfortable is the
| lack of one-way valves to make it easier to breath in them.
| In industry, when you actually need to wear a
| mask/respirator, they almost always have valves.
|
| Unfortunately, we got stuck on the "wear masks to protect
| others" narrative, and people who actually were at risk were
| prevented from wearing much more effective, much more
| comfortable, masks that would actually work well at
| protecting them. Eg here in Canada, it's illegal to wear a
| mask/respirator with a valve on a plane.
| matz1 wrote:
| Not only that, there is one more thing to carry when you go
| out and impairment of social interaction because of lack of
| facial expression.
| slashdot2008 wrote:
| I don't think it is an unfortunate narrative. two people
| wearing masks without valves is twice the reduction in
| likelihood that either one gives the other covid. If
| someone does have covid the mask without the valve will
| greatly reduce the concentration of virus particles in the
| air around them. I think that is working as intended!
| petertodd wrote:
| Masks that aren't worn correctly tend to have very low
| efficiencies, because the air just bypasses the mask at
| the edges. Depends on many factors like the type, how
| hard you are breathing, etc. But filtering just 20% of
| the air breathed in is quite possible. And let's face it,
| people intentionally wear them incorrectly all the time
| because they suck to wear.
|
| If you and I both have 50% filtration, that's the
| equivalent of 75% filtration. For the person who is
| vulnerable, that is much less effective than just wearing
| a 95% minimum filtration valved N95 mask/respirator
| properly.
|
| It's just ridiculous that an elderly man on a flight,
| sitting next to a healthy 15 year old more likely to be
| killed by a flu infection(1), will be told to take off
| his valved N95 respirator here in Canada, to protect that
| 15 year old. I have friends who have seen this happen
| first hand.
|
| 1) https://www.cdc.gov/flu/symptoms/flu-vs-covid19.htm
| makomk wrote:
| With the typical masks available to and worn by ordinary
| people, exhalation pressure seems to cause a lot of air
| to bypass the mask too - except that instead of doing it
| via a well-designed valve that redirects the airflow
| somewhere sensible, it blows out the top and steams up
| glasses or out the sides and towards whoever's standing
| behind you.
| neither_color wrote:
| I'm my state we have a choice now and I still wear one most
| places except the gym. That's where my comfort vs risk
| threshold crosses. On that note one thing that's odd that
| I've observed in mixed mask rooms is that I don't like
| exposing my face to people who aren't exposing theirs. It's
| like my smile, a sign of peace, can't be reciprocated so I'm
| making myself vulnerable at their expense. I'll don a mask in
| mixed mask rooms not because of conformity per se, but what
| feels like defensiveness. My simian brain is thinking "you
| don't know if these are friendlies." I'm looking forward to
| any future psychological studies that explain this
| phenomenon.
| [deleted]
| mhb wrote:
| 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 and others.
| auxym wrote:
| Last I checked in Canada, N95 masks are still about 3$ a pop
| for disposable, single use masks from industrial
| distributors. Pre pandemic, we bought 3M 8210s for about 15
| cents in boxes of 160. I wouldn't call the current situation
| available and cheap.
|
| Oh, and if you thought surgical masks were mildly
| uncomfortable, N95s are an order of magnitude worst. They
| pretty much need a perfect seal with your face and the 3Ms
| use a really tight rubber band to achieve that. 2 bands,
| actually.
|
| I currently work on site and wear surgical masks all day,
| it's fine. Not sure I would want to do the same if it was
| N95s.
| Louis_Sarwal wrote:
| The discomfort is a sign that they may work.
|
| Not proof--but a sign.
|
| They are expensive, and I do not reccommend wearing them. I
| do not reccommend doing anything, expecially anything that
| has a high chance of bringing unknown costs.
| mhb wrote:
| 3M 8210s are US $26 for 20 now. $1.30 per mask seems pretty
| reasonable to me, but I've never bought them in industrial
| quantities so don't have that anchor.
|
| I've worn N95s for hours (actually P95s which have a nicer
| seal) and I agree that they're less comfortable than less
| effective alternatives. But it is a bit curious that people
| are concerned enough to be wearing their homemade mask
| alone in a car or walking outside by themselves but are
| unwilling to endure the slight additional discomfort of a
| known effective mask.
| DanBC wrote:
| > a known effective mask.
|
| ...if you got a real one, and not one of the less
| effective fakes.
| mulmen wrote:
| 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.
| mhb wrote:
| That's reasonable and also what I would like. But what is
| the mental model of someone wearing their mask alone in the
| woods or in their car?
|
| So, yes, we should explain why an N95 is better than a
| handkerchief, but it seems like there are plenty of people
| who don't care about the details and just need to be told
| that one is more effective.
| cataflam wrote:
| > what is the mental model of someone wearing their mask
| alone (...) in their car?
|
| It could be to set and fit their masks once before
| leaving home, and not touching it, removing it, and
| putting it back again during all their activities, each
| time they come in and out of buildings/shops, etc. even
| if it means wearing it alone in their car part of the
| time.
| DanBC wrote:
| > Once N95 masks became readily available and cheap, it was
| (and is) mysterious why people weren't being told to wear
| them
|
| Because they're difficult to wear. There are a _bunch_ of
| photos on social media of HCPs who 've got bruised faces
| after correctly wearing N95 / FPP3 for a day or two.
| bitcurious wrote:
| I'm not sure there was any popular doubt over the efficacy of
| N95 masks. The problem was rather getting one - marketplaces
| like Amazon restricted access to masks if you weren't
| affiliated with a hospital. So you were left with sketchy deals
| and weird vendor sites.
|
| I suspect Amazon killed quite a few people over the last year
| by restricting access - supply scaled pretty quickly.
| Laforet wrote:
| According to the data presented, surgical masks are still
| highly effective even after converting the scales to linear.
| Add social distancing on top, it is almost as good as N95.
|
| And I very much doubt that N95 masks are effectively utilized
| by the general public considering how many poorly fitted
| masks I have seen over the past year.
|
| Before the pandemic there had been several studies looking at
| the efficacy of N95 vs. surgical masks at preventing the
| transmission of influenza in hospitals. Most of them never
| got anywhere because it was soon realized that even doctors
| and nurses cannot be trusted to wear and change masks
| properly during the daily routine. Let's hope things have
| improved by now.
| bsder wrote:
| > And I very much doubt that N95 masks are effectively
| utilized by the general public considering how many poorly
| fitted masks I have seen over the past year.
|
| I agree. When people can't even wear surgical masks
| properly, there's no hope with an N95.
|
| > Most of them never got anywhere because it was soon
| realized that even doctors and nurses cannot be trusted to
| wear and change masks properly during the daily routine.
| Let's hope things have improved by now.
|
| At the very least, everybody is washing their hands. Before
| Covid, you couldn't even get all the doctors to do
| something even that simple.
| kickopotomus wrote:
| Unfortunately, a few of my friends fell victim to the Qanon
| conspiracy bandwagon and the fact that mask pore size is
| wider than the virus was heavily circulated as a reason for
| mask ineffectiveness.
| petertodd wrote:
| That wasn't a Quanon conspiracy: that was misunderstanding
| that I saw plenty of mainstream doctors and other health
| professionals promote. What it showed is that either they
| were intentionally lying - which I kinda doubt - or that
| they were so confident in what they had heard that they
| never bothered to do any research for themselves. Just
| reading the relevant wikipedia pages carefully would have
| corrected that misunderstanding.
| XorNot wrote:
| This is your not frequent enough reminder that "doctor"
| is not a synonym for "scientist", or more specifically
| epidemiologist.
|
| Medical doctor's are basically mechanic's for the human
| body. The human body is complex, so this is a high bar to
| clear and an important function, but it doesn't magically
| grant them knowledge about concepts outside that field.
| blumomo wrote:
| Everyone is having assumptions about these observations.
| The conclusions might not be always right, but at least the
| observation is real. And when you observe that mask
| mandating states don't do significantly better than mask-
| free states, then a curious mind rightfully starts
| pondering. No need to unterstand conspiracy theories (a
| difficult topic) to understand that science isn't getting
| it right yet.
| cforrester wrote:
| > And when you observe that mask mandating states don't
| do significantly better than mask-free states, then a
| curious mind rightfully starts pondering.
|
| _If_ this is true, which I haven 't confirmed, wouldn't
| that say more about the effectiveness of political policy
| rather than about masks themselves? When we have seen
| throughout the pandemic that healthcare workers have a
| dramatically lower rate of infection compared to the
| general population, despite having more direct contact
| with infected populations, it is clear to the that proper
| precautions including protective equipment (principally
| masks, for a respiratory disease) can impede COVID
| transmission heavily. With that being the case, the
| question becomes: has mask policy been effective in
| getting enough people to wear masks properly and
| consistently, in states where it is mandated?
| Louis_Sarwal wrote:
| Q is a symbol used by pedophiles to say that they are pedos
| ;). Just look at "Q", and you will see what I mean. Nothing
| complex about it.
| viraptor wrote:
| You could get halfway with other solutions. The 3-layer
| design with the synthetic layer in the middle tries to
| achieve the same idea. It's not going to be as effective as a
| certified N95, but it's better than a simple cloth. Not sure
| how common the idea was globally, but it was quite common to
| make them in Australia.
| kadoban wrote:
| Unfortunately there is _absolutely_ popular doubt about this,
| and every other thing you likely think is obvious about covid
| and the world. I don't think educating people about masks is
| really the answer though. I don't know what the answer is, or
| if there even is one. Feel like our society is coming apart
| at the seams.
| tgsovlerkhgsel wrote:
| The US seems to have relied heavily on cloth masks, even long
| after the shortages were over. From my understanding,
| surgical masks are much more effective (while often being
| more comfortable) than community/cloth masks. (I don't have a
| source for this on hand, but the German government did ban
| cloth masks/require at least surgical masks in many areas for
| this reason.)
|
| I suspect a lot of that was out of a desire to not appear as
| backtracking on a previous position.
| Louis_Sarwal wrote:
| We immediately face this issue: You should not act on
| information, or even knowledge. You should act on WISDOM.
| Wisdom is hard to gain, and yet it proves itself time after
| time to be better than the other forms of truth. Education is
| not the key; That would be wisdom. I do admit that most of what
| they teach is falsehood, and it would be better if it were
| truth.It would be better of there were no education at all than
| what we have now. In fact, it would be better to have no
| education system at all than to have a good education system
| that is liable to deteriorate. This is especially true when
| that system is a cost and a burden to and on society. Your
| information, however, is hardly better than the "n95 is coffee
| filter". There is no good proof on how airborne viruses are
| transmitted! Wearing a mask may do nothing, or it may do
| everything(Well, it can't do everything. Masks haven't stopped
| gov't from the vaccine)! It is likely that much of the
| transmission is not even caused by the oral and nasal areas,
| but instead is due to fecal aerosols. Our best solution may be
| the abolition of apartments and shared housing. SOme sort of
| filter should be put on the toilets, not on our faces.
| Cleansing chemicals(like bleach) should be put in the toilets,
| not in our arms.
|
| Let us remember that choices should be made carefully, with
| consideration, and only once all of the facts are present.
|
| Let us not be hasty-We must wait until a length of time has
| past in which effects which take alonger time to present
| themselves are presented.
|
| This may require the foregoing of many necessary things. But
| such is the cost of life. Such is necessary to avoid death, or
| things much worse.
| goatcode wrote:
| The only time "N95" was uttered was last year, when we were
| being told: 1. Masks aren't needed; 2. Don't buy masks,
| healthcare workers need them.
|
| It's unfortunate that we didn't go back to talking about proper
| masks before people started knitting them and making them out
| of rags and beads. One wonders what difference it might have
| made.
| slver wrote:
| Bless your soul, but what I've learned from the way we handled
| the pandemic worldwide (and are still handling it) is that
| information that's readily available and should in theory reach
| everyone, flows ridiculously slowly, even among specialists and
| political figures, it's easily corrupted and distorted, and a
| loud ignorant minority counts as much in the public discourse,
| as the voices of millions of reasonable people.
|
| I'd say we have more evolving to do. Both biologically and
| socially. Individually (some) of us are relatively smart.
| Together we're as dumb as a piece of wood.
| ihsw wrote:
| I can't help but look at some peoples' rejection of public
| health guidance in the US as "not a bug/won't fix."
|
| The relevant authorities (including traditional mainstream
| media) injected politics into the public discourse, which
| destroyed trust in what should be a normal public health
| process. Not only that but the relevant leaders of agencies
| decided to try manage the supply of masks through "steering"
| the public by downplaying the usefulness of masks.
|
| Distrust of untrustworthy leaders is a feature, not a bug.
| simpleguitar wrote:
| Absolutely. Considering how long it took CDC and WHO to even
| acknowledge airborne transmission, even though the Chinese
| were very clear about it from very early on.
|
| https://www.nytimes.com/2021/05/07/opinion/coronavirus-
| airbo...
| bellyfullofbac wrote:
| Yeah, it's disappointing to see how I still see people
| wearing their masks incorrectly, e.g. just over the mouth and
| not covering their noses.
|
| Sometimes I think human beings are advanced, but then I walk
| into a public toilet and I see evidence how many are still no
| better than animals. It's a simple technology, urinate into
| the hole where the water can wash it away and we'll remain
| hygienic, but a lot of people still fail at that.
| LatteLazy wrote:
| I get where you are coming from but something I've learned from
| this pandemic is that "wear a mask" is too complex and
| burdensome for a significant proportion of people in the
| west...
| boldpandabear wrote:
| Whole study is flawed. This is theoretical math philosophy, not a
| study. A viral particle has never been isolated outside its host,
| therefore these authors have no idea of the viral concentration
| in an airborne particle and are just making stuff up.
| vondur wrote:
| 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.
| omginternets wrote:
| 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.
| brobdingnagians wrote:
| This isn't a study; it is a mathematical model [1].
|
| > Here, we develop a quantitative model of airborne virus
| exposure that can explain these contrasting results and provide a
| basis for quantifying the efficacy of face masks. We show that
| mask efficacy strongly depends on airborne virus abundance. Based
| on direct measurements of SARS-CoV-2 in air samples and
| population-level infection probabilities, we find that the virus
| abundance in most environments is sufficiently low for masks to
| be effective in reducing airborne transmission.
|
| Meanwhile, they ignore the dozens of studies showing masks are
| ineffective, or even counterproductive:
|
| https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/
|
| https://pubmed.ncbi.nlm.nih.gov/29395560/
|
| https://pubmed.ncbi.nlm.nih.gov/32590322/
|
| https://pubmed.ncbi.nlm.nih.gov/15340662/
|
| https://pubmed.ncbi.nlm.nih.gov/26579222/
|
| https://pubmed.ncbi.nlm.nih.gov/31159777/
|
| https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779801/
|
| https://pubmed.ncbi.nlm.nih.gov/19216002/
|
| https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/
|
| https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2493952/pdf/ann...
|
| https://www.nap.edu/catalog/25776/rapid-expert-consultation-...
|
| https://www.nap.edu/read/25776/chapter/1#6
|
| https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article
|
| https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6599448/
|
| https://www.acpjournals.org/doi/10.7326/M20-1342
|
| https://link.springer.com/article/10.1007/s00392-020-01704-y
| omegaworks wrote:
| Half the articles on your list are tangential (masks make it
| marginally harder to exercise, ok duh). The article posted
| helps us understand why the viral concentration in the
| environment also impacts efficacy, it helps explain why some of
| the articles you posted see inconclusive results.
| toss1 wrote:
| And even the "masks make it marginally harder to exercise" is
| likely wrong.
|
| The winner of the 10,000m race at the 2019 USA Track & Field
| Championships wore a mask against his pollen allergies. [1]
|
| Worn properly, they just disappear. I wear N95s a work for
| many tasks, and they are mildly distracting for a few
| minutes, then I forget about them. Even more so now with
| wearing them for the pandemic.
|
| Yes, education about masks could be a LOT better, but using
| that is more anti-mask FUD is borderline sociopathic.
|
| [1] https://www.oregonlive.com/trackandfield/2011/06/galen_ru
| pp_...
| makomk wrote:
| According to that article, the winner of the 10,000m race
| wore a mask to protect against his allergies for the first
| 4,000m, by which point it was just too uncomfortable to
| continue wearing: "Rupp said Salazar told him to "wear it
| as long as you can. As soon as it starts to get real hot or
| uncomfortable, or starts to stick and get sweaty, throw it
| off." The mask came flying off after 4,000 meters. But Rupp
| was content to bide his time until the 9,200-mark."
| jmull wrote:
| You really hurt your credibility when the first link doesn't
| support the argument you claim it does.
| dmead wrote:
| you really had that list ready to go...
| chrischattin wrote:
| Yeah, this right here. Masks efficacy for stopping viral
| transmission has been heavily studied. I could post literally
| hundreds more examples of statistically significant, RCT'd
| science showing they have no effect on viral transmission.
|
| Wearing masks has never been about the science.
| oarfish wrote:
| Interesting how some of the linked studies either contradict
| your statement, or seem to have nothing to do with it.
| brobdingnagians wrote:
| Some are indirectly related, but all are linked in some way.
| Like how some find that it _could_ have a positive effect and
| postulate how, but that the studies they reviewed in the
| meta-review didn't _show_ that.
| takeda wrote:
| The study about mask being ineffective is about cloth mask.
| That's why the hospital masks are no longer made of cloth.
| brobdingnagians wrote:
| That is true; but a large number of people are walking around
| with cloth masks believing that they are helpful, while that
| study has shown them to potentially increase risk.
|
| It did show "Penetration of cloth masks by particles was
| almost 97% and medical masks 44%." So that was a positive for
| medical masks. Though some of the other studies address how
| those need to be used properly and not re-used.
|
| The main point is that, in general, media has not done a good
| job of transmitting studies on risk reduction; they've mainly
| done propaganda, which can do more harm by promoting things
| like cloth masks and not informing people about proper use of
| medical masks.
| microdrum wrote:
| You are exactly correct, and being downvoted because of
| religious zealotry. This is a mathematical model. Yes, face
| coverings cover the face. It's a long (and ultimately
| disproven) leap to: face coverings materially suppress virus in
| a society of millions of people.
| antattack wrote:
| Results only apply to indoor environment. Maybe source control
| could be extrapolated to outdoor conditions and close contact.
| mrfusion wrote:
| Even if this is true, I still don't think someone at high risk
| should be trusting their life to a piece of cloth.
| pmoriarty wrote:
| _" This is an open-access article distributed under the terms of
| the Creative Commons Attribution license, which permits
| unrestricted use, distribution, and reproduction in any medium,
| provided the original work is properly cited."_
|
| So happy to see that.
| fawciwouchy wrote:
| Fauci funded the Wuhan Lab to specifically do gain of function
| research - FACT.
|
| Fauci should be arrested.
|
| Fauci should be executed.
|
| Maskers are nothing but a bunch of brown shirts.
| splitrocket wrote:
| Not that this will settle anything.
|
| Anecdotally, I've not gotten even a slight cold while being
| socially distanced while consistently masked.
| freeflight wrote:
| It's not just an anecdote, it's measurable on a global scale
| [0]
|
| [0] https://www.nature.com/articles/d41586-020-03519-3
| neither_color wrote:
| Anecdotally I haven't had a cold in years. I work out 4 days a
| week and while I wouldn't call it a strict diet I have an upper
| limit calorie "budget" that I never exceed. While it's
| certainly possible that masks helped some people avoid all
| airborne transmissions last year, lots of people were also able
| to exercise more and make better food choices without the rush
| of breakfast and lunch commutes.
| XorNot wrote:
| I made absolutely no changes 1 year, but because my workspace
| at work was in an alcove next to an air conditioning vent
| that pulled air from the outside, I completely dodged the
| office cold because I basically had my own positive pressure
| environment.
|
| It's more likely your lifestyle is simply keeping you away
| from people and places that experience high levels of foot
| traffic.
| poutine wrote:
| Get kids. They are plague carriers.
| michaelhah wrote:
| Well, that may be due to other people social distancing enough
| to keep the level of colds down. It might have nothing to do
| with masks.
| bryanrasmussen wrote:
| anecdotally, I have very little social contact normally anyway,
| I've worked from home since before winter, and always wear
| masks in closed public spaces - have had 3-4 colds in that
| time.
|
| I do have kids though.
| jackfoxy wrote:
| Anecdotally, since taking vitamin D3 supplements I haven't
| been getting colds. Added daily nutritional zinc supplements
| in 2020 as soon as they were available after I heard the
| anecdotal evidence D & zinc are effective in Covid
| prevention. Throughout winter and early spring last year you
| couldn't get zinc supplements for love or money.
|
| A lot of anecdotes there :).
|
| The American medical establishment has a long history of not
| getting behind nutritional disease prevention. Some of it is
| for good reason, but I think there is also a systemic bias.
| space_ghost wrote:
| My frequency of colds has increased 10x since I've gotten
| married and had kids.
| goatcode wrote:
| >got a cold
|
| That's because the cold virus is spread by surfaces, and you
| likely touched something with it, then scratched your eyes. You
| can be 80 miles from someone, but if you touch something he
| touched, you're potentially getting his cold.
| andrew_ wrote:
| My 2yo would like to sneeze on you and flip that anecdote on
| its head.
| MrDunham wrote:
| Parent of a 1.5 year old here. Can confirm - several colds.
|
| To the parent comment's point though, I haven't had any colds
| in the last year where my daughter wasn't sick first
| poutine wrote:
| They seem to have perpetual runny noses when they're really
| young.
| awb wrote:
| Years ago my entire family got sick and I was determined not
| to contract it through distancing and frequent hand washing
| and sanitizing. It worked until I bent down to tie my
| toddler's shoes only to look up and mid-sentence have him
| cough directly into my open mouth. All it takes is one
| mistake. Needless to say I got sick shortly after.
| Marsymars wrote:
| A few years ago I went on vacation for a week with a half-
| dozen friends in an Airbnb and spent the entire time
| miserably sick with some kind of respiratory illness. I was
| similarly determined not to get anyone else sick (and I was
| sick from the start, so avoided any asymptomatic period). I
| was fastidious about distancing and sanitizing, and any
| time I needed to cough I'd step outside of the house.
| Nobody else got sick. Is the sample size here large enough
| to determine anything? No idea, but I like the anecdote.
| samatman wrote:
| I wonder what the result would have been if you immediately
| gargled with vodka.
|
| I've used that successfully in the past to chase colds out
| of the throat before they get into my nose and lungs.
| jMyles wrote:
| It's more plausible, at least in my view, that this is the
| result of suppression of several endemic respiratory pathogens
| by viral interference (something that has been observed in
| previous pandemics).
|
| https://medium.com/illumination-curated/the-unexpected-case-...
| tryonenow wrote:
| >Surgical masks with particle collection efficiencies around ~50%
| cannot prevent the release of millions of particles per person
| and their inhalation by others (green dots in Fig. 1, B and D).
| In other words, the human-emitted respiratory particle number is
| so high that we cannot avoid inhaling particles generated by
| another person even when wearing a surgical mask
|
| So the entire premise of the modeling in the paper rests on the
| assumption that surgical masks can filter some percentage of
| viral particles. It's my understanding that viral particles are
| around 3 orders of magnitude smaller than the pores in surgical
| masks. So is there any evidence that surgical masks can filter
| aerosolized viral particles?
| cr1895 wrote:
| Here's a nice interactive graphic showing how masks block
| particles:
|
| https://www.nytimes.com/interactive/2020/10/30/science/wear-...
| neither_color wrote:
| That's a very cool visualization and I wish I'd seen it
| before. I am curious though as to what makes some viruses
| have higher R values than others. These masks more
| effectively stopped influenza and I still don't understand
| why.
| noname120 wrote:
| Viral particles are concentrated in droplets and aerosols,
| which are significantly blocked by surgical masks.
| splitrocket wrote:
| Virus particles do not travel naked in the air, instead they
| are colloidally suspended in liquid, both droplets and
| aerosols.
|
| So, if your filter catches the droplets and aerosols, which are
| much larger in size than the actual virus, the filter works.
| abfan1127 wrote:
| assuming: 1) 100% capture of air flow 2) no fatigue (ie
| capture is same at t=0, and t=later)
|
| anyone with glasses will tell you 1 isn't a very good
| assumption. As masks saturate in moisture, back pressure
| causes (1) to be more false.
| takeda wrote:
| Realization that somebody's droplets are getting into your
| mouth and nose makes one want to wear mask even after
| pandemic is over :)
| viraptor wrote:
| You may want to check how much of your body weight is
| bacterial and how easy it is to exchange samples with
| others. Just own the things that make us human.
| cimi_ wrote:
| You're of course free to do whatever you think makes sense,
| but please don't expect other people to follow. The world
| is full of risks, but everything is a tradeoff - it's
| really bad if we start thinking random people are a danger
| to us.
|
| And for what it's worth, I'm not anti-mask in the context
| of the pandemic - I've been wearing masks indoors since the
| whole thing started and I'll continue to do this until most
| people around me are vaccinated, for their sake.
| neilwilson wrote:
| Except that field data shows they don't because they are not
| used precisely as required - which means the filter doesn't
| work effectively if at all and then it becomes infectious
| waste that isn't treated and disposed of correctly.
|
| Human system effects dominate - as the field data shows. It's
| like HCQ - works in a lab, not in the real world.
|
| Might be useful in tightly controlled medical settings with
| adequate filtered ventilation. But there's no hard evidence
| beyond that at this stage.
|
| Feynman's rule still applies.
| blumomo wrote:
| Science is based a lot on assumptions and beliefs. A scientist
| who _does not_ consciously say: ,,We have observed that...
| which makes us believe that..." still ultimately becomes a
| victim of his unconsciously formed belief system, a pseudo-
| religion.
|
| I'm a software engineer, I work scientifically, but I don't own
| the truth. I own the thought process which works on top of
| assumptions. But I don't want my own work to feel like magic,
| and to avoid that, I observe and try to understand it. But at
| the end of the day I have to say: ,,I _assume_ that my program
| is bug free because I have observed many test runs in which the
| program behaved correctly. I _belief_ it will work well at the
| customer.
|
| Same has to be said for above study. Otherwise we wouldn't find
| studies which even claim the opposite. These other studies are
| just based on different assumptions and belief systems.
| AstralStorm wrote:
| As suspected, it's exactly a probability game. If there's few
| infectious particles sure to low concentrations (e.g. people
| distance or are outdoors), you would roll the 70% penetration
| chance fewer times, and result in very few particles reaching
| deeper into lungs too as the velocities are reduced.
|
| When very close to an active particle source, you'd roll the
| conditional probability dice many more times.
|
| The critical number is the base infectivity or viability. (CFU
| essentially) It is expected that sub-viable numbers might even
| work as a kind of vaccination if people isolate long enough.
| (stay at home for prolonged time without contact - scale of days
| at least)
| nradov wrote:
| There is no evidence that inoculation with sub-viable numbers
| of virions works at all as a kind of vaccination. It's an
| interesting hypothesis but no one has done the human challenge
| trials necessary to test it.
| epivosism wrote:
| Yes. Crazy how hard it has been for people to get this:
|
| Imagine a bulletproof vest with three larger-than-bullet-sized
| holes in it. Say you know someone is going to shoot ten bullets
| at you - would you not wear the vest because "the attack vector
| can fit through the pores"?
|
| The point is people treat this as a binary 'safe' / 'not safe'
| switch, when actually risk is related to the distribution of
| exposure to dosage.
| fawciwouchy wrote:
| Fake science.
|
| Fake news.
|
| Burn your mask!
| joshuaengler wrote:
| The VAST majority of mask wearing I have seen in California has
| been average cloth-covers. I have only seen a handful of people
| out of thousands actually wearing N95 masks, so perhaps N95 is
| highly effective at stopping viruses, but I see basically nobody
| wearing that. Stores, offices, buildings, all are completely fine
| with you wearing a bandana over your face. There is effectively
| no point in even mandating mask laws unless you actually mandate
| the TYPE of mask that must be used. The coffee filters people are
| wearing over their face will do close to nothing, if not even
| make everything worse for their own personal health (lung issues,
| bacterial infections, etc.)
| jonas21 wrote:
| I've never seen anyone wearing a coffee filter over their face.
| What are you talking about?
| omginternets wrote:
| >The coffee filters people are wearing over their face will do
| close to nothing
|
| I'm not an expert, but I believe this is not quite accurate. As
| I understand it, even a piece of cloth helps prevent the spread
| of the virus to _others_. The mechanism is that the virus exits
| your nose /mouth in the form of macroscopic droplets that later
| break down into microscopic droplets a few inches from your
| face. A bandanna will catch the big droplets before they split
| apart.
| jayd16 wrote:
| Is there some global increase in lung issues (besides covid) or
| bacterial infections or something?
| anonymousiam wrote:
| Here's the manufacturer's (3M) label:
|
| WARNING: This respirator helps protect against certain
| particulate contaminants but does not eliminate exposure to or
| the risk of contracting any disease or infection. Misuse may
| result in sickness or death. For proper use, see supervisor, or
| User Instructions.
|
| https://multimedia.3m.com/mws/media/1837275O/3m-9132-healthc...
| ekianjo wrote:
| So one can make a model out of thin air and not validate it, and
| then write a paper about it claiming to have the holy grail?
| That's Science in 2021?
| fawciwouchy wrote:
| The only reason the CDC decided to provide "guidance" on lifting
| mask use indoors was because there is now sufficient evidence to
| not just prove the fact that it did indeed come from the Wuhan
| lab but Fauci and the NIH FUNDED IT.
| [deleted]
| tgsovlerkhgsel wrote:
| 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?
| FiReaNG3L wrote:
| No you didn't miss anything - most people upvoting this didn't
| read anything more than the title.
| Louis_Sarwal wrote:
| So true.
| neolog wrote:
| The paper is fine, the title is clickbait.
| omegaworks wrote:
| It invites rigor in studying mask efficacy. Some studies out
| there show inconclusive results of mask usage, and this article
| helps give us an explanation as to why we might be seeing that.
| The model shows that in an extremely virus-rich environment
| masking can be rendered ineffective, but in virus-poor
| environments, even surgical masks decrease the probability of
| infection.
|
| Researchers need to measure concentration of virus in the
| environment as well as mask usage to show the efficacy of masks
| in real world situations.
| rsj_hn wrote:
| 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 respiratory particles that may penetrate masks is
| substantial, which is one of the main reasons leading to doubts
| about their efficacy in preventing infections. _Moreover,
| randomized clinical trials show inconsistent or inconclusive
| results, with some studies reporting only a marginal benefit or
| no effect of mask use (5, 6)_. Thus, surgical and similar masks
| are often considered to be ineffective. 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?
|
| Here, we develop a quantitative model of airborne virus
| exposure that can explain these contrasting results and provide
| a basis for quantifying the efficacy of face masks. "
|
| So they are left with a conundrum that _places_ which use
| surgical masks seem to be better off, whereas _randomized
| control studies_ of surgical masks show little to no benefit.
| This is what they try to explain with a mathematical model.
| function_seven wrote:
| > _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 may be--also
| behave in other ways to limit the spread. They minimize time
| spent in public indoor spaces, they keep distance from other
| people, they're more likely to self-quarantine if a family
| member is sick, etc.
|
| The mask-wearing prevalence is a proxy for how serious the
| wearer takes Covid as a threat.
| wrycoder wrote:
| 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.
| BugsJustFindMe wrote:
| The mistake that many people make, and that I think you're
| implicitly making here too, is this notion of "controlled
| study". If the study denies the result seen time and again in
| real life, perhaps the study isn't studying correctly.
| admissionsguy wrote:
| Working down from the conclusion to find the necessary
| assumptions is the standard approach to COVID-related
| questions.
| Louis_Sarwal wrote:
| Probably not. Most things like this are like this. There may
| indeed be some underlying proof, but they either can't or won't
| show it to you-if it exists. It is more likely that it does
| not. They start with their conclusion. They rarely commence an
| empirical study, because that might prove their prepared
| conclusion wrong! A model, which can be used in place of
| reality, is not reality, and never will be. GIGO. The model was
| tailored to match their wanted results, or more likely they
| made a bad model and tweaked it to gain desired results. This
| does not mean that masks are bad-it just means that the methods
| used are generally false. Properly gained empirical evidence
| should be used, and it even should not be trusted if it points
| to you doing something stupid-like wearing a tissue on your
| face all day.
| stretchwithme wrote:
| If high resolution video is to be believed, masks reduce how many
| particles get into the air when we cough, sneeze or talk.
|
| https://www.youtube.com/watch?v=H2azcn7MqOU
| microdrum wrote:
| A science study that only shows, as this one does, that face
| coverings cover the face is not very useful. The public policy
| piece is much more complex. High masking states did NOT do better
| on COVID than low masking states.
| tgsovlerkhgsel wrote:
| By what metric? By deaths per capita, my impression was the low
| masking states did worse, but I didn't rigorously check the
| data.
| truthwhisperer wrote:
| waste of time. we should not promote face mask
| tester756 wrote:
| Aren't masks mostly/also about decreasing the area of the air
| that you pull in (closer to you, or in other words the distance
| from which you pull is smaller)?
|
| like take a piece of paper in front of your face and breath with
| mask and without
| AlexCoventry wrote:
| No. https://www.youtube.com/watch?v=0Tp0zB904Mc
| cr1895 wrote:
| Masks work by trapping particles exhaled or inhaled.
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