25 ms·

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

324 points by paultgriffiths 5y ago

tryonenow 5y ago
>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?
- noname120 5y ago
  Viral particles are concentrated in droplets and aerosols, which are significantly blocked by surgical masks.
- splitrocket 5y ago
  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.
  - takeda 5y ago
    Realization that somebody's droplets are getting into your mouth and nose makes one want to wear mask even after pandemic is over :)
    - viraptor 5y ago
      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_ 5y ago
      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.
    - nfvme 5y ago
      You a poor excuse for a human being.
  - neilwilson 5y ago
    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.
  - abfan1127 5y ago
    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.
  - tryonenow 5y ago
    Aerosols are explicitly defined as particulate with long settling time, and are differentiated from droplets by their size, with arbitrarily defined cutoffs on the order of 1um [0]. The pore size of surgical masks is in the range of 16-146um [1] (surprisingly hard to find). So whether or not the masks filter aerosolized covid-19 is a valid question and these downvotes are merely reflexive conditioning. Even the question of whether surgical masks reduce infection after surgery was recently controversial, long before covid. This science is not settled. And it's in line with at least two sources which demonstrated negligible or no reduction in covid spread from surgical masks. Plus, cloth mask pore size is orders of magnitude larger than than that of surgical masks and whether they block aerosols on the order of 1um is extremely dubious. 0. https://wwwnc.cdc.gov/eid/article/12/11/06-0426_article https://wwwnc.cdc.gov/eid/article/12/11/06-0426_article 1. https://www.researchgate.net/publication/242297437_The_Relationship_of_Fabric_Properties_and_Bacterial_Filtration_Efficiency_for_Selected_Surgical_Face_Masks https://www.researchgate.net/publication/242297437_The_Relat...
- blumomo 5y ago
  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.
- cr1895 5y ago
  Here’s a nice interactive graphic showing how masks block particles: https://www.nytimes.com/interactive/2020/10/30/science/wear-mask-covid-particles-ul.html https://www.nytimes.com/interactive/2020/10/30/science/wear-...
  - neither_color 5y ago
    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.
    - jwlake 5y ago
      Google cross-protection and competition in respiratory viruses. Lots of pre-2019 literature.
tester756 5y ago
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 5y ago
  No. https://www.youtube.com/watch?v=0Tp0zB904Mc https://www.youtube.com/watch?v=0Tp0zB904Mc
- cr1895 5y ago
  Masks work by trapping particles exhaled or inhaled.
splitrocket 5y ago
Not that this will settle anything. Anecdotally, I've not gotten even a slight cold while being socially distanced while consistently masked.
- michaelhah 5y ago
  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 5y ago
  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.
  - space_ghost 5y ago
    My frequency of colds has increased 10x since I've gotten married and had kids.
  - jackfoxy 5y ago
    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.
- andrew_ 5y ago
  My 2yo would like to sneeze on you and flip that anecdote on its head.
  - MrDunham 5y ago
AstralStorm 5y ago
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)
- epivosism 5y ago
  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.
  - ppf 5y ago
    If we're talking about the size of the holes in a mask compared to a virus, then it would be more like wearing a "bulletproof" vest full of holes 10x bigger than a bullet.
    - epivosism 5y ago
      But the area which does have coverage is still significant, right?
    - epivosism 5y ago
      I guess it's a choice of analogy. If virus particles are like bullets, protection can be viewed as proportional. But if it's viewed more like a liquid, seeping through any hole, then only full watertight protection works. I'd argue that the reduced transmissibility we see from outdoor exposure supports the first of those as a more apt analogy.
thewizardofaus 5y ago
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 5y ago
  protip: shower once a month to train your immune system during lockdown
- astrange 5y ago
  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.
sschueller 5y ago
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.
- deleted 5y ago
  [deleted]
- bitcurious 5y ago
  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.
  - kickopotomus 5y ago
    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 5y ago
      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.
boldpandabear 5y ago
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.
brobdingnagians 5y ago
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://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/ https://pubmed.ncbi.nlm.nih.gov/29395560/ https://pubmed.ncbi.nlm.nih.gov/29395560/ https://pubmed.ncbi.nlm.nih.gov/32590322/ https://pubmed.ncbi.nlm.nih.gov/32590322/ https://pubmed.ncbi.nlm.nih.gov/15340662/ https://pubmed.ncbi.nlm.nih.gov/15340662/ https://pubmed.ncbi.nlm.nih.gov/26579222/ https://pubmed.ncbi.nlm.nih.gov/26579222/ https://pubmed.ncbi.nlm.nih.gov/31159777/ https://pubmed.ncbi.nlm.nih.gov/31159777/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779801/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779801/ https://pubmed.ncbi.nlm.nih.gov/19216002/ https://pubmed.ncbi.nlm.nih.gov/19216002/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2493952/pdf/annrcse01509-0009.pdf https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2493952/pdf/ann... https://www.nap.edu/catalog/25776/rapid-expert-consultation-on-the-effectiveness-of-fabric-masks-for-the-covid-19-pandemic-april-8-2020 https://www.nap.edu/catalog/25776/rapid-expert-consultation-... https://www.nap.edu/read/25776/chapter/1#6 https://www.nap.edu/read/25776/chapter/1#6 https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6599448/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6599448/ https://www.acpjournals.org/doi/10.7326/M20-1342 https://www.acpjournals.org/doi/10.7326/M20-1342 https://link.springer.com/article/10.1007/s00392-020-01704-y https://link.springer.com/article/10.1007/s00392-020-01704-y
- dmead 5y ago
  you really had that list ready to go...
- chrischattin 5y ago
  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.
antattack 5y ago
Results only apply to indoor environment. Maybe source control could be extrapolated to outdoor conditions and close contact.
mrfusion 5y ago
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 5y ago
"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.
anonymousiam 5y ago
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-healthcare-particulate-respirator-and-surgical-mask-user-instructions.pdf https://multimedia.3m.com/mws/media/1837275O/3m-9132-healthc...
- adrr 5y ago
  Because they are just NIOSHA certified and not FDA. Only certain N95s are have gone through testing and certification to be cleared for medical use.
- userbinator 5y ago
  That's standard legal ass-covering.
- randomopining 5y ago
  “Does not eliminate” aka it may reduce probability. Imagine the brain of people that don’t understand simple probability lol.
- simpleguitar 5y ago
  Notice the word 'eliminate'. Nobody could claim something would 'eliminate exposure or risk of contracting any disease' and not get sued immediately by someone who got sick. In Wuhan, something like 10,000 doctors were sent in to treat the thousands in field hospitals. None of them caught covid during that time. N95s work, if worn properly (and pass a fit test, even a crude one).
tgsovlerkhgsel 5y ago
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 5y ago
  No you didn't miss anything - most people upvoting this didn't read anything more than the title.
  - Louis_Sarwal 5y ago
    So true.
- omegaworks 5y ago
  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 5y ago
  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.
microdrum 5y ago
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 5y ago
  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 5y ago
waste of time. we should not promote face mask
joshuaengler 5y ago
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 5y ago
  I've never seen anyone wearing a coffee filter over their face. What are you talking about?
  - Grimm665 5y ago
    I haven't either but I did have to drive several miles out of my way a few months ago to get coffee filters at the only store in the state that seemed to have them in stock. I was told during checkout people were buying them in bulk to use as masks.
    - jonas21 5y ago
      Or buying them in bulk... to make coffee? I'd assume that if people are working from home, they're also making coffee at home instead of getting it at work or on the way to work. And that would be a pretty reasonable explanation for shortages of filters that fit in home coffee makers. I know my personal use of coffee filters went up about 10x during the pandemic. And no, they were not on my face.
      - unishark 5y ago
        I would think a paper filter filters a lot better than cloth at least. The problem is breathing through it of course (as opposed to around). I searched and see some projects on the internet where people are trying to use them. Seems like a worthwhile idea to me.
ekianjo 5y ago
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?
- logicchains 5y ago
  >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 Academic Finance in Forever.
- unishark 5y ago
  Works best if it fits the bias/agenda of the journal editors. The better you do that, the more weaknesses they will forgive.
deleted 5y ago
[deleted]
vondur 5y ago
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 5y ago
  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.
  - nostrebored 5y ago
    Counterpoint: Miami
    - dragonwriter 5y ago
      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.)
      - beagle3 5y ago
        I don’t know the details here, but in the Israel vs Sweden comparison, absolute numbers favor Israel (7000 vs 14000 dead) but age normalized are the same (Sweden has about twice as many >60), and in European normalized excess death measures from Oxford, Sweden is at 2% and Israel at 6% Personally, I try to only use excess death figures, because case counts are not comparable due to local policies. E.g. once vaccination started, Israel categorically stopped testing vaccinees unless they show clear covid symptoms; whereas it demands weekly test from many unvaccinated even though they have no symptoms.
fawciwouchy 5y ago
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.
fawciwouchy 5y ago
Fake science. Fake news. Burn your mask!
fawciwouchy 5y ago
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.
stretchwithme 5y ago
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 https://www.youtube.com/watch?v=H2azcn7MqOU
davidhyde 5y ago
For those of you who haven’t seen the slowmoguys video about talking with and without a mask this is good: https://youtu.be/gZ66wJFD3bs https://youtu.be/gZ66wJFD3bs If you want to skip the technical lighting bits then jump to the 4 minute mark. It’s difficult to argue against footage like that and it makes you wonder why some people take off their masks to talk.
- perryizgr8 5y ago
  > wonder why some people take off their masks to talk. Because voice is muffled by the mask and makes it very hard to understand in some cases. Taking off the mask is not acceptable, but it is not an unjustified response.
sjg007 5y ago
We know masks work for infection control which is why they are used in hospitals and also in clean room style manufacturing.
- beagle3 5y ago
  Bacteria and viruses behave differently. It’s possible, even likely, that a measure against one will be ineffective against the other. In an attempt to fights a specific virus, namely sarscov2 - no, we don’t know that masks work. The cdc numbers I saw talk about 2% reduction in vivo.
xbar 5y ago
I was very happy to see "aerosols are physically defined as airborne solid or liquid particles with diameters smaller than 100 μm" as opposed to the bad 5 μm definition that caused so much trouble.
nfvme 5y ago
Why is it that mask nazis are in the same group of people that support terrorists and hate Jews so much?
lt9f423 5y ago
Look at all these libtards that don't believe in masks and science and aren't wearing a mask at the white house: https://twitter.com/Breaking911/status/1395448471306620933 https://twitter.com/Breaking911/status/1395448471306620933
lt9f423 5y ago
Masks are like the new condoms from the 90s. Brought to by the same murderous nazi Dr. Fauci: https://aep.lib.rochester.edu/node/49111 https://aep.lib.rochester.edu/node/49111 "Anthony Fauci, you are a murderer and should not be the guest of honor at any event that reflects on the past decade of the AIDS crisis." "Anthony Fauci, you are a liar because you have known for years that CD4 counts are a travesty of a surrogate marker that, through drug company coercion, have been elevated to the status of "a standard." "You are a pill-pushing pimp that cooperates with drug companies in forcing dangerous concoctions down the throats of a desperate community that is brainwashed into believing that taking a pill, any pill, will help them." "Ten years of hope? Fuck that. Try a decade of death and greed. Go back to Washington you bastard."
- lt9f423 5y ago
  downvote all you want nazis!
avereveard 5y ago
"in our specific model which we specifically created around the exact conditions required for them to work"
vondro 5y ago
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.
- adrianb 5y ago
  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.
teleforce 5y ago
Obligatory story on Manchurian plague epidemic regarding how surgical mask come to be a standard requirement during the treatment of any airborne disease [1][2]. Mind you that the original surgical mask was not invented for surgery, it was invented for the treatment of patients with airborne virus. Heck, every.single.time you meets someone who are skeptical about the effectiveness of the mask in mitigating the airborne virus transmission, just send them this story [1][2]. It also interesting to note that the inventor of the surgical mask Dr. Wu, (the doctor mentioned in the article) is not even the resident of Imperial China at the time, even though he is the first Chinese medical doctor trained and graduated from the University of Cambridge. The last Empire of China or Qing dynasty who was originally come from Manchuria, had to hire the best medical doctor that they can find in order the save the citizens native of Manchuria, from the raging epidemic. Dr. Wu has come very close to get the Noble price in medicine back in 1935 due to his novel surgical mask invention. [1]https://insightplus.mja.com.au/2020/15/dr-wu-lien-teh-hero-of-the-pandemic-mask/ https://insightplus.mja.com.au/2020/15/dr-wu-lien-teh-hero-o... [2]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4291938/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4291938/
- incrudible 5y ago
  The Wu Lien-Teh mask is the precursor of KN95 masks, not surgical masks. See this: https://de.m.wikipedia.org/wiki/Datei:How_the_gauze-cotton_mask_should_be_worn.jpg https://de.m.wikipedia.org/wiki/Datei:How_the_gauze-cotton_m... Surgical masks offer virtually no (personal) protection against airborne disease and fulfill a completely different purpose.
  - teleforce 5y ago
    Based on the design and capability, I doubt Dr Wu original mask back in the pandemic was even close to N95 mask in filtering the air probably closer to the surgical mask of today, if not worst. The N95 as we know today was invented just recently in 1995[1]. Even with its rudimentary design, Dr Wu's mask had managed to save many lives back then, and in my opinion surgical mask of today will be similar if not better than the original Dr. Wu's mask design. [1]https://en.wikipedia.org/wiki/N95_respirator https://en.wikipedia.org/wiki/N95_respirator
incrudible 5y ago
...in hamsters? In mice? No, in a mathematical model - the gold standard of junk science.
Kurtose 5y ago
Anecdata from a _very_ frequent flyer: Naomi Campbell’s Airport Routine (2019). Makes sense to me. https://youtu.be/b-U_jT9qWvs https://youtu.be/b-U_jT9qWvs
egberts 5y ago
“... is still under debate ...” - NEXT!
domano 5y ago
We are in pandemic-mode for over a year now - isn't it obvious that masks help by now?
collyw 5y ago
Doesn't seem to have been effective here, we have had to wear them including outdoors since October. But give me some model over real world data to convince me.
rdmirza 5y ago
I did not bother to read this thread in its entirety though I typically enjoy HN discussion. Undoubtedly, masks of any quality work. Airborne viruses still exist in secretions (likely, in much higher concentrations). Secretions sometimes even carry living cells, would you imagine (in fact the #1 cause of sputum sample contamination for C&S; the bane of internists everywhere). High velocity events certainly increase the environment-load of secretion and thereby virus. You don't need evidence in all cases. Im sorry to say, to the otherwise curious-minded, this is one of those cases.

>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?

noname120 5y ago
Viral particles are concentrated in droplets and aerosols, which are significantly blocked by surgical masks.
splitrocket 5y ago
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.
- takeda 5y ago
  Realization that somebody's droplets are getting into your mouth and nose makes one want to wear mask even after pandemic is over :)
  - viraptor 5y ago
    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_ 5y ago
    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.
  - nfvme 5y ago
    You a poor excuse for a human being.
- neilwilson 5y ago
  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.
- abfan1127 5y ago
  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.
- tryonenow 5y ago
  Aerosols are explicitly defined as particulate with long settling time, and are differentiated from droplets by their size, with arbitrarily defined cutoffs on the order of 1um [0]. The pore size of surgical masks is in the range of 16-146um [1] (surprisingly hard to find). So whether or not the masks filter aerosolized covid-19 is a valid question and these downvotes are merely reflexive conditioning. Even the question of whether surgical masks reduce infection after surgery was recently controversial, long before covid. This science is not settled. And it's in line with at least two sources which demonstrated negligible or no reduction in covid spread from surgical masks. Plus, cloth mask pore size is orders of magnitude larger than than that of surgical masks and whether they block aerosols on the order of 1um is extremely dubious. 0. https://wwwnc.cdc.gov/eid/article/12/11/06-0426_article https://wwwnc.cdc.gov/eid/article/12/11/06-0426_article 1. https://www.researchgate.net/publication/242297437_The_Relationship_of_Fabric_Properties_and_Bacterial_Filtration_Efficiency_for_Selected_Surgical_Face_Masks https://www.researchgate.net/publication/242297437_The_Relat...
blumomo 5y ago
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.
cr1895 5y ago
Here’s a nice interactive graphic showing how masks block particles: https://www.nytimes.com/interactive/2020/10/30/science/wear-mask-covid-particles-ul.html https://www.nytimes.com/interactive/2020/10/30/science/wear-...
- neither_color 5y ago
  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.
  - jwlake 5y ago
    Google cross-protection and competition in respiratory viruses. Lots of pre-2019 literature.

tester756 5y ago

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 5y ago
No. https://www.youtube.com/watch?v=0Tp0zB904Mc https://www.youtube.com/watch?v=0Tp0zB904Mc
cr1895 5y ago
Masks work by trapping particles exhaled or inhaled.

splitrocket 5y ago

Not that this will settle anything. Anecdotally, I've not gotten even a slight cold while being socially distanced while consistently masked.

michaelhah 5y ago
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 5y ago
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.
- space_ghost 5y ago
  My frequency of colds has increased 10x since I've gotten married and had kids.
- jackfoxy 5y ago
  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.
andrew_ 5y ago
My 2yo would like to sneeze on you and flip that anecdote on its head.
- MrDunham 5y ago

AstralStorm 5y ago

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)

epivosism 5y ago
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.
- ppf 5y ago
  If we're talking about the size of the holes in a mask compared to a virus, then it would be more like wearing a "bulletproof" vest full of holes 10x bigger than a bullet.
  - epivosism 5y ago
    But the area which does have coverage is still significant, right?
  - epivosism 5y ago
    I guess it's a choice of analogy. If virus particles are like bullets, protection can be viewed as proportional. But if it's viewed more like a liquid, seeping through any hole, then only full watertight protection works. I'd argue that the reduced transmissibility we see from outdoor exposure supports the first of those as a more apt analogy.

thewizardofaus 5y ago

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 5y ago
protip: shower once a month to train your immune system during lockdown
astrange 5y ago
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.

sschueller 5y ago

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.

deleted 5y ago
[deleted]
bitcurious 5y ago
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.
- kickopotomus 5y ago
  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 5y ago
    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.

boldpandabear 5y ago

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.

brobdingnagians 5y ago

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://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/ https://pubmed.ncbi.nlm.nih.gov/29395560/ https://pubmed.ncbi.nlm.nih.gov/29395560/ https://pubmed.ncbi.nlm.nih.gov/32590322/ https://pubmed.ncbi.nlm.nih.gov/32590322/ https://pubmed.ncbi.nlm.nih.gov/15340662/ https://pubmed.ncbi.nlm.nih.gov/15340662/ https://pubmed.ncbi.nlm.nih.gov/26579222/ https://pubmed.ncbi.nlm.nih.gov/26579222/ https://pubmed.ncbi.nlm.nih.gov/31159777/ https://pubmed.ncbi.nlm.nih.gov/31159777/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779801/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779801/ https://pubmed.ncbi.nlm.nih.gov/19216002/ https://pubmed.ncbi.nlm.nih.gov/19216002/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2493952/pdf/annrcse01509-0009.pdf https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2493952/pdf/ann... https://www.nap.edu/catalog/25776/rapid-expert-consultation-on-the-effectiveness-of-fabric-masks-for-the-covid-19-pandemic-april-8-2020 https://www.nap.edu/catalog/25776/rapid-expert-consultation-... https://www.nap.edu/read/25776/chapter/1#6 https://www.nap.edu/read/25776/chapter/1#6 https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6599448/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6599448/ https://www.acpjournals.org/doi/10.7326/M20-1342 https://www.acpjournals.org/doi/10.7326/M20-1342 https://link.springer.com/article/10.1007/s00392-020-01704-y https://link.springer.com/article/10.1007/s00392-020-01704-y

dmead 5y ago
you really had that list ready to go...
chrischattin 5y ago
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.

antattack 5y ago

Results only apply to indoor environment. Maybe source control could be extrapolated to outdoor conditions and close contact.

mrfusion 5y ago

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 5y ago

"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.

anonymousiam 5y ago

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-healthcare-particulate-respirator-and-surgical-mask-user-instructions.pdf https://multimedia.3m.com/mws/media/1837275O/3m-9132-healthc...

adrr 5y ago
Because they are just NIOSHA certified and not FDA. Only certain N95s are have gone through testing and certification to be cleared for medical use.
userbinator 5y ago
That's standard legal ass-covering.
randomopining 5y ago
“Does not eliminate” aka it may reduce probability. Imagine the brain of people that don’t understand simple probability lol.
simpleguitar 5y ago
Notice the word 'eliminate'. Nobody could claim something would 'eliminate exposure or risk of contracting any disease' and not get sued immediately by someone who got sick. In Wuhan, something like 10,000 doctors were sent in to treat the thousands in field hospitals. None of them caught covid during that time. N95s work, if worn properly (and pass a fit test, even a crude one).

tgsovlerkhgsel 5y ago

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 5y ago
No you didn't miss anything - most people upvoting this didn't read anything more than the title.
- Louis_Sarwal 5y ago
  So true.
omegaworks 5y ago
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 5y ago
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.

microdrum 5y ago

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 5y ago
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 5y ago

waste of time. we should not promote face mask

joshuaengler 5y ago

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 5y ago
I've never seen anyone wearing a coffee filter over their face. What are you talking about?
- Grimm665 5y ago
  I haven't either but I did have to drive several miles out of my way a few months ago to get coffee filters at the only store in the state that seemed to have them in stock. I was told during checkout people were buying them in bulk to use as masks.
  - jonas21 5y ago
    Or buying them in bulk... to make coffee? I'd assume that if people are working from home, they're also making coffee at home instead of getting it at work or on the way to work. And that would be a pretty reasonable explanation for shortages of filters that fit in home coffee makers. I know my personal use of coffee filters went up about 10x during the pandemic. And no, they were not on my face.
    - unishark 5y ago
      I would think a paper filter filters a lot better than cloth at least. The problem is breathing through it of course (as opposed to around). I searched and see some projects on the internet where people are trying to use them. Seems like a worthwhile idea to me.

ekianjo 5y ago

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?

logicchains 5y ago
>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 Academic Finance in Forever.
unishark 5y ago
Works best if it fits the bias/agenda of the journal editors. The better you do that, the more weaknesses they will forgive.

deleted 5y ago

[deleted]

vondur 5y ago

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 5y ago
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.
- nostrebored 5y ago
  Counterpoint: Miami
  - dragonwriter 5y ago
    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.)
    - beagle3 5y ago
      I don’t know the details here, but in the Israel vs Sweden comparison, absolute numbers favor Israel (7000 vs 14000 dead) but age normalized are the same (Sweden has about twice as many >60), and in European normalized excess death measures from Oxford, Sweden is at 2% and Israel at 6% Personally, I try to only use excess death figures, because case counts are not comparable due to local policies. E.g. once vaccination started, Israel categorically stopped testing vaccinees unless they show clear covid symptoms; whereas it demands weekly test from many unvaccinated even though they have no symptoms.

fawciwouchy 5y ago

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.

fawciwouchy 5y ago

Fake science. Fake news. Burn your mask!

fawciwouchy 5y ago

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.

stretchwithme 5y ago

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 https://www.youtube.com/watch?v=H2azcn7MqOU

davidhyde 5y ago

For those of you who haven’t seen the slowmoguys video about talking with and without a mask this is good: https://youtu.be/gZ66wJFD3bs https://youtu.be/gZ66wJFD3bs If you want to skip the technical lighting bits then jump to the 4 minute mark. It’s difficult to argue against footage like that and it makes you wonder why some people take off their masks to talk.

perryizgr8 5y ago
> wonder why some people take off their masks to talk. Because voice is muffled by the mask and makes it very hard to understand in some cases. Taking off the mask is not acceptable, but it is not an unjustified response.

sjg007 5y ago

We know masks work for infection control which is why they are used in hospitals and also in clean room style manufacturing.

beagle3 5y ago
Bacteria and viruses behave differently. It’s possible, even likely, that a measure against one will be ineffective against the other. In an attempt to fights a specific virus, namely sarscov2 - no, we don’t know that masks work. The cdc numbers I saw talk about 2% reduction in vivo.

xbar 5y ago

I was very happy to see "aerosols are physically defined as airborne solid or liquid particles with diameters smaller than 100 μm" as opposed to the bad 5 μm definition that caused so much trouble.

nfvme 5y ago

Why is it that mask nazis are in the same group of people that support terrorists and hate Jews so much?

lt9f423 5y ago

Look at all these libtards that don't believe in masks and science and aren't wearing a mask at the white house: https://twitter.com/Breaking911/status/1395448471306620933 https://twitter.com/Breaking911/status/1395448471306620933

lt9f423 5y ago

Masks are like the new condoms from the 90s. Brought to by the same murderous nazi Dr. Fauci: https://aep.lib.rochester.edu/node/49111 https://aep.lib.rochester.edu/node/49111 "Anthony Fauci, you are a murderer and should not be the guest of honor at any event that reflects on the past decade of the AIDS crisis." "Anthony Fauci, you are a liar because you have known for years that CD4 counts are a travesty of a surrogate marker that, through drug company coercion, have been elevated to the status of "a standard." "You are a pill-pushing pimp that cooperates with drug companies in forcing dangerous concoctions down the throats of a desperate community that is brainwashed into believing that taking a pill, any pill, will help them." "Ten years of hope? Fuck that. Try a decade of death and greed. Go back to Washington you bastard."

lt9f423 5y ago
downvote all you want nazis!

avereveard 5y ago

"in our specific model which we specifically created around the exact conditions required for them to work"

vondro 5y ago

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.

adrianb 5y ago
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.

teleforce 5y ago

Obligatory story on Manchurian plague epidemic regarding how surgical mask come to be a standard requirement during the treatment of any airborne disease [1][2]. Mind you that the original surgical mask was not invented for surgery, it was invented for the treatment of patients with airborne virus. Heck, every.single.time you meets someone who are skeptical about the effectiveness of the mask in mitigating the airborne virus transmission, just send them this story [1][2]. It also interesting to note that the inventor of the surgical mask Dr. Wu, (the doctor mentioned in the article) is not even the resident of Imperial China at the time, even though he is the first Chinese medical doctor trained and graduated from the University of Cambridge. The last Empire of China or Qing dynasty who was originally come from Manchuria, had to hire the best medical doctor that they can find in order the save the citizens native of Manchuria, from the raging epidemic. Dr. Wu has come very close to get the Noble price in medicine back in 1935 due to his novel surgical mask invention. [1]https://insightplus.mja.com.au/2020/15/dr-wu-lien-teh-hero-of-the-pandemic-mask/ https://insightplus.mja.com.au/2020/15/dr-wu-lien-teh-hero-o... [2]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4291938/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4291938/

incrudible 5y ago
The Wu Lien-Teh mask is the precursor of KN95 masks, not surgical masks. See this: https://de.m.wikipedia.org/wiki/Datei:How_the_gauze-cotton_mask_should_be_worn.jpg https://de.m.wikipedia.org/wiki/Datei:How_the_gauze-cotton_m... Surgical masks offer virtually no (personal) protection against airborne disease and fulfill a completely different purpose.
- teleforce 5y ago
  Based on the design and capability, I doubt Dr Wu original mask back in the pandemic was even close to N95 mask in filtering the air probably closer to the surgical mask of today, if not worst. The N95 as we know today was invented just recently in 1995[1]. Even with its rudimentary design, Dr Wu's mask had managed to save many lives back then, and in my opinion surgical mask of today will be similar if not better than the original Dr. Wu's mask design. [1]https://en.wikipedia.org/wiki/N95_respirator https://en.wikipedia.org/wiki/N95_respirator

incrudible 5y ago

...in hamsters? In mice? No, in a mathematical model - the gold standard of junk science.

Kurtose 5y ago

Anecdata from a _very_ frequent flyer: Naomi Campbell’s Airport Routine (2019). Makes sense to me. https://youtu.be/b-U_jT9qWvs https://youtu.be/b-U_jT9qWvs

egberts 5y ago

“... is still under debate ...” - NEXT!

domano 5y ago

We are in pandemic-mode for over a year now - isn't it obvious that masks help by now?

collyw 5y ago

Doesn't seem to have been effective here, we have had to wear them including outdoors since October. But give me some model over real world data to convince me.

rdmirza 5y ago

I did not bother to read this thread in its entirety though I typically enjoy HN discussion. Undoubtedly, masks of any quality work. Airborne viruses still exist in secretions (likely, in much higher concentrations). Secretions sometimes even carry living cells, would you imagine (in fact the #1 cause of sputum sample contamination for C&S; the bane of internists everywhere). High velocity events certainly increase the environment-load of secretion and thereby virus. You don't need evidence in all cases. Im sorry to say, to the otherwise curious-minded, this is one of those cases.