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Advice that masks don't help for coronavirus woefully wrong?

masks coronavirus

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#31 Florin

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Posted 09 July 2020 - 06:35 PM

The counter arguments, prepublished :-D :
 
Masks and respirators do not work.

There have been extensive randomized controlled trial (RCT) studies, and meta-analysis reviews
of RCT studies, which all show that masks and respirators do not work to prevent respiratory
influenza-like illnesses, or respiratory illnesses believed to be transmitted by droplets and
aerosol particles.

Furthermore, the relevant known physics and biology, which I review, are such that masks and
respirators should not work. It would be a paradox if masks and respirators worked, given what
we know about viral respiratory diseases: The main transmission path is long-residence-time
aerosol particles (< 2.5 μm), which are too fine to be blocked, and the minimum-infective-dose
is smaller than one aerosol particle.


The counter arguments, countered.
 
Observational arguments
 
If masks and respirators didn't work, all of the health workers that have been in contact with COVID-19 patients should be infected by now, and countries such as Japan should be full of COVID-19 cases. But this hasn't happened.
 
Physics and biology arguments

  • The claim that aerosol particles less than 2.5 μm are too fine to be blocked is wrong; an N95 can block at least 98% of all viral particles.
  • The 2% of particles that might leak from an infected person's N95 would be further diluted by room air changes, unfavorable humidity, and other N95s.
  • It's unclear how relevant the minimum-infective-dose is outside of lab conditions where airborne particles might become physically degraded due to environmental conditions such as sunlight or infection might be avoided by the fact that higher humidity would help cilia and mucus function correctly.
  • While the minimum-infective-dose might be even less the one aerosol particle under some circumstances, those virus particles won't necessarily make it from one person's mouth or nose to another's due to dilution effects.

Consider the following scenario. Two people, one of whom is infected, wear N95s without an exhalation valve in close proximity indoors. The indoor air is changed several times every hour and the humidity is 50%. At most, 2% of the aerosols leak out, but they get severely diluted by the number of hourly air changes, 50% humidity, and uninfected person's N95. Also, the infected person would only be infectious for a few days. So, the probability of even one of those aerosols passing through two N95s seems miniscule. And even if a few do make it through at some point, they won't necessarily land inside the respiratory system; they could easily get stuck to the face or inside of the mask.
 
No, it's probably not literally impossible to become infected even if everyone wore N95s, but you'd likely have to hang around infected people for a long time for you to become infected yourself. It would probably take so long for people to become infected that the pandemic would quickly burn itself out.
 
And regardless of anything else, masks reduce the chance of developing severe disease, because they prevent exposure to massive viral loads and increase humidity in the respiratory system (which is crucial for fighting infections).


Edited by Florin, 09 July 2020 - 06:42 PM.

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#32 Dorian Grey

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Posted 09 July 2020 - 08:37 PM

I feel the value of masks is different in different situations.  In an airplane?  Oh heck yea!  Outdoors on a breezy Summer day (provided you're not in a crowd), not so much.  

 

It's important to understand, both droplets and aerosols are generated only by coughing, sneezing & most importantly vocalizing.  If you're walking quietly down an uncrowded street, you're not exhaling great clouds of virus with every breath & if you should happen to pass someone, the odds of contagion is next to nil.  I'm in California, & wear a mask outdoors to keep the peace, but if I happen to cross paths with someone not wearing one, I don't panic.  Even if he/she happens to cough or is yammering on the phone, I just halt my inhalation for a couple of seconds as we pass.  

 

I'm happy with mask requirements indoors in public places, but the outdoor mandate is a bit absurd outside of stadiums or areas of crowding.  I'm betting the mask backlash could be greatly reduced if more science based regulation was utilized.  


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#33 Florin

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Posted 09 July 2020 - 09:53 PM

It's important to understand, both droplets and aerosols are generated only by coughing, sneezing & most importantly vocalizing. 

 

Aerosols can also be generated by breathing.

 

https://www.news-med...hows-study.aspx


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#34 pamojja

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Posted 09 July 2020 - 09:56 PM

Personally I also wear a mask in places it's still mantatory here (public transport only) for not worsening anxiety in others. Though there are always some who don't, and it meanwhile seems tolerated. Due to all my comorbidities in remission, and everything supplemental recommended for boosting immunity already in my long-term daily stack (used to effect the remissions), I really don't fear this virus personally (the chance to die from it, compared to all my other serious comorbidities are just too slim). If I could, I would prefer to get infected now in the summertime. The mask not being N-95, I still hope they indeed collect viruses and give my immunity a chance to train. Or maybe I'm lucky and already had it in February/March with the colds in India? - But alas, I don't know anyone who knows anyone infected. Nor anyone who knows anyone who died from it. So it seems really difficult to get it here.

 

What I believe after 20 years of complete failures in creating a corona-virus vaccine, there isn't any other option than to get over it. Or stay in lock-down and starve for the next decade. Which with the manipulated public opinion is what actually will happen for at least next year. Creating a depression like last time 90 years ago. And an multiple times worse excess-mortality than covid ever could.

 

So yes, if I get a chance to go on my yearly vacation next January, I will wear a mask in the plane and wherever required in the hope to collect viruses and train my immunity. The evidence for non-airtight surgical masks keeping tiny viruses out is just too slim.

 

 


Edited by pamojja, 09 July 2020 - 10:08 PM.

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#35 Dorian Grey

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Posted 09 July 2020 - 11:33 PM

Aerosols can also be generated by breathing.

 

https://www.news-med...hows-study.aspx

 

I won't pretend I know for a fact normal breathing couldn't possibly generate some aerosols, but I am curious about how this has been documented or might even theoretically occur.  Have they actually seen or filmed clouds of micro-droplets with specialized lighting coming out through normal respiration, or is it believed individual virus simply break free in the air moving through our pipes and fly free?  

 

From what I've read, all airborne virus originates and is carried by droplet or micro-droplet aerosol that evaporate into droplet nuclei.  Have never heard of virus literally taking wing & flying on their own.  Even vapor that condenses on exhalation in cold weather was still in a vapor state as it leaves our mouth/nose.  

 

Again, not saying this can not occur, but I'd love to see any real evidence this exists to any realistic extent.  I guess it's possible that wheezing associated with pulmonary disease or infection might liberate some aerosol/micro-droplets, so I'll grant it is at least theoretically plausible.  Sounds like a stretch to me though.  

 

EDIT:

 

OK, this just popped up as suggested reading from the link you gave:

https://www.news-med...s-per-hour.aspx

 

COVID-19 patients exhale millions of viral particles per hour

 

"The team estimates that the exhaled emission rate of SARS-CoV-2 was about 1,000 to 100,000 virus particles per minute, with the highest rate seen during the early stages of COVID-19."

 

“Most SARS-CoV-2 in exhaled breath should fall in the fine aerosol size (<2.5µm) ranges, which can remain airborne for a far longer time than the coarser ones emitted otherwise in a sneeze or cough,” said Yao and colleagues.  "

 

“Evidence from our work shows that exhaled breath emission may well be the most significant SARS-CoV-2 shedding mechanism,” write the researchers."

 

---------------

 

Still find this concept quite bizarre.  Apparently based on cultures from COVID patient rooms.  Did they document these patients never coughed, spoke or sneezed in these rooms?  How much of this type of aerosol could even be captured by a mask?

 

EDIT:

 

OK here's the study: https://www.medrxiv....5.31.20115154v1

 

"exhaled breath condensate (EBC) samples had the highest positive rate"   Amazing!  I stand corrected!  


Edited by Dorian Grey, 10 July 2020 - 12:18 AM.

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#36 Florin

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Posted 09 July 2020 - 11:53 PM

Another argument in favor of mask wearing is that only a small amount of aerosols are emitted by talking, coughing, sneezing, or breathing; the vast majority of virus particles are emitted in droplets which even a simple cloth mask can completely block.

Face Masks Against COVID-19: An Evidence Review
https://www.preprint.../202004.0203/v2


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#37 seivtcho

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Posted 10 July 2020 - 05:20 AM

Virus just like that floating in the air by itself is not valid for the coronavirus. It is either in a cell, or in a drop.

 

In Bulgaria people stopped wearing masks and infected cases skyrocketed.

 

I persoanlly wear both - mask and face shield.

 

 


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#38 Florin

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Posted 10 July 2020 - 07:52 PM

Virus just like that floating in the air by itself is not valid for the coronavirus. It is either in a cell, or in a drop.

 

Actually, it is valid. Most virus particles are emitted in droplets, but if the person emitting them isn't wearing a mask, the smaller droplets that don't fall to the ground immediately evaporate and become aerosols and float in the air for hours. If everyone is wearing cloth masks, the amount of aerosols will be minimal, but if just one infected person isn't wearing one and hangs around, cloth masks won't protect anyone from the infected person's droplets-turned-into-aerosols.


Edited by Florin, 10 July 2020 - 08:02 PM.

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#39 seivtcho

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Posted 11 July 2020 - 04:29 PM

Samller coronavirus drops that don't fall on the ground?

 

From what we have been told, the coronavirus flyes at arround a meter and falls down on the ground. That was the reason for the social distancing of 1,5 meters...

 

Are there coronavirus droplets, that are not under the law of the gravity and continue to flow?

 

 

 


Edited by seivtcho, 11 July 2020 - 04:30 PM.


#40 Florin

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Posted 11 July 2020 - 06:12 PM

Apparently, most droplets do fall to the ground, but smaller droplets stay in the air a little longer and that gives them enough time to evaporate and turn into aerosols. Humidity might also affect how many droplets turn into aerosols. Also, a small amount of aerosols are generated immediately and don't go through a droplet phase. Some of the previously posted links provide more details.

 

Social distancing probably helps a little, but without mask wearing, it's not that effective.

 

Rather than assume that coronavirus (or any other new and dangerous respiratory virus) can't be airborne, everyone should have assumed the worst way before this pandemic started and recommended that everyone stockpile and use elastomeric respirators indoors. Future pandemics could be caused by bioterrorism and could wipe out civilization, so we better get used to wearing elastomerics ASAP.


Edited by Florin, 11 July 2020 - 06:44 PM.

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#41 seivtcho

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Posted 11 July 2020 - 06:49 PM

Everything I can say for sure is my "emperical knowledge" if I may say it so.

 

I simply know, that all of my my medical collegues, who wear masks did not get the disease. Even those, who didn't wear face shields.

 

How... Why...

Can the virus pass through the mask... Can it not...

Does the virus fly... Does the virus land...

Is it a spray... is it in droplets and cells...

 

Masks protect.

 

 


Edited by seivtcho, 11 July 2020 - 06:50 PM.

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#42 Florin

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Posted 11 July 2020 - 07:13 PM

But other health care workers have become infected and died. Not wearing at least an N95 in a hospital setting and especially during procedures that can generate massive amounts of aerosols is playing Russian roulette.


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#43 geo12the

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Posted 13 July 2020 - 12:06 AM

  

 

Have they actually seen or filmed clouds of micro-droplets with specialized lighting

 

 

 

https://www.facebook...266057788032983


Edited by geo12the, 13 July 2020 - 12:08 AM.

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#44 seivtcho

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Posted 14 July 2020 - 11:12 AM

Does this video show the airflow arround the mask, or the clouds of micro-droplets?

 

Air surely goees through the mask, otherwise we all who wear masks will sufficate lol :) but is that video proving the micro-droplets going through the mask?

A plastic bag tightly stretched arround your head for example will stop even the airflow in and out your head, but it is definately not recommended lol.

 

If microdroplets carrying viruses travel just like that in and out through the mask, then many years of medical knowledge postulating, that the masks protect against air born diseases goes in the garbage.

 

And, no matter how ill informed I am, I still believe, that masks protect against that kind of diseases. And I still will be wearing mine :)  Among all of my debunked arguments, still one remained, it is that the number of the infected in my country rised in times, after the wearing of masks stopped being obligate.

 

Yes, I know some medical personnel infected and even died from COVID19, but not among my friends. It seems we are wearing quality filters.

 

 

 

 


Edited by seivtcho, 14 July 2020 - 11:23 AM.

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#45 gamesguru

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Posted 14 July 2020 - 12:36 PM

No one ever claimed masks "stop" disease from spreading.  If you're debating against that, you're debating against a strawman or red herring that no one from the opposing camp even argued for.

 

Nevertheless, a preponderance of evidence too great for the margins of this post on an Android device has convinced me masks do help, with good ones preventing probably 70-90% of airborn infections.  Anyone who disagrees simply needs to see the evidence, and it is growing by the day.

 

See: Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population (an NCBI meta-analysis)

 

A compilation of studies: https://www.reddit.c...o/mask_studies/

 

A critical write-up of science and time pressures: https://www.cidrap.u...-science-during

 

Study showing NEGATIVE effect of carelessly re-used masks: https://pubmed.ncbi....h.gov/25903751/

 

Even if they aren't effective, that's really a negativist position in a situation where the burden of proof has negative utility for the other.  This is distinguished from religious prayer, for example, if you refuse to pray to God and he is truly possessed of such an uncool vanity as to punish those who question his existence, then your negative skepticism and failure to prayer will result in your going to Hell but not your neighbor's going to Hell.  This is contrasted with the ethics of the COVID-19 situation, wherein a stubbornness against masks in the face of scientific uncertainty could result in unnecessary suffering and deaths of other people.  Basically, it's highly dressed up and indirect murder.

 

So no, we don't know if masks help or to what extent.  Yes, they are an inconvenience til then.  But I would argue it is an inconvenience which could potentially keep your fellow many alive, and therefore is one which is worth inconveniencing ourselves into more is conclusively known.


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#46 seivtcho

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Posted 14 July 2020 - 01:35 PM

Strange thing the destiny is.

 

The solution against a totally new threat may be not in developing new strategies, but in turning to the past.

 

The masks was known for protecting against the airborn pathogens at least from the 70's. Maybe even much earlier. One stupid trivial even banal mask. An usual bottle of 70% alcochol, produces in tons worldwide A chep piece of plastic tighted arround your head used from the doctors for decades, wearing the brave name of "Face shield". Thats what it takes to prevent the disease.

 



#47 geo12the

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Posted 14 July 2020 - 03:16 PM

Though for some reason many will say "more research is needed on masks, we don't know if they work" if you look up "masks" and "viruses" on Pubmed there are tons of published studies going back years and they all show that to varying degrees they masks do work. They have unfortunately been politicized. Are they 100%? Of course not. But they provide some protection and combined with other measures make sense.  


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#48 gamesguru

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Posted 14 July 2020 - 03:39 PM

Exactly.  So let's suppose they provide some degree of protection, and it's significant.  Then what are all the doubters left hanging to? Just that pathetic piece of driftwood called American entitlement, which has been misinforming and demonizing the other from the start.  The same bigoted ghouls telling you the virus was a hoax are now peddling baseless conspiracy theories about masks and urging to re-open NOW.  Shameful.  One longs in reading their posts to know how many of them doubt climate change or oppose the affordable care act.  Seems like ignorance and sociopathy run deep in their veins


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#49 geo12the

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Posted 14 July 2020 - 05:15 PM

Exactly.  So let's suppose they provide some degree of protection, and it's significant.  Then what are all the doubters left hanging to? Just that pathetic piece of driftwood called American entitlement, which has been misinforming and demonizing the other from the start.  The same bigoted ghouls telling you the virus was a hoax are now peddling baseless conspiracy theories about masks and urging to re-open NOW.  Shameful.  One longs in reading their posts to know how many of them doubt climate change or oppose the affordable care act.  Seems like ignorance and sociopathy run deep in their veins

 

You make me think of one of my MAGA friends. I had actually mentioned him in my previous post as an example of an anti-masker but edited him out before posting. A nice person, would give you the shirt of his back, but consumed by MAGA identity politics and is anti-mask, climate change denier, Trump can do no wrong it goes on a on. And now putting his small business at risk by not allowing his employees to wear masks and is claiming he is being persecuted by "cancel culture". I tried to reason with him about putting his business at risk but to no avail and have given up.  I despise extremism of both the left and right but in America today right wing extremism is so crazy it's unreal. 


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#50 gamesguru

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Posted 14 July 2020 - 06:35 PM

I mean obviously politicizing it won't help, stupid people are all the more likely to be stubbornly offended and obstinate in their beliefs. Any obvious or direct line of inquiry to the contrary of their beliefs will be met with immediate contempt, dismissal, and shallow refutation—no matter how congenial or concessional the tone.

 

This COVID denial tendency is more than political, even despite a strong correlation.  It's a biological, statistical, psychological thing.  On the surface it's a simple tendency of thought, toward naive optimism and away from meticulous analysis. But my fears are it runs much deeper than that. A fantasy world of wishes is built up, while more pressing facts go over their head and are quickly tossed aside.


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#51 osris

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Posted 18 July 2020 - 10:25 AM

 

I would add none of your sources on masks are definitive analyses either, merely opinionated interpretations of flawed studies.  I would add anyone refusing to wear a mask is going against the scientific current, and should be the one providing more evidence than not.  I would add it is odd how you are the one consistently turning the flame of skepticism round, refusing to expand on your sources or prove your claims with primary sources, and somehow despite me being the more scientific i am deserving more doubt?  Please prove your claim that masks don't help now I'm on the edge of my seat mate

 

Sit on the edge of your seat no longer.

 

Here are some sources to the extensive scientific literature that establishes that wearing masks is pointless in preventing viral spread:
 
Jacobs, J. L. et al. (2009) “Use of surgical face masks to reduce the incidence of the common cold among health care workers in Japan: A randomized controlled trial,” See: American Journal of Infection Control, Volume 37, Issue 5, 417 – 419. https://www.ncbi.nlm...pubmed/19216002
 
“N95-masked health-care workers (HCW) were significantly more likely to experience headaches. Face mask use in HCW was not demonstrated to provide benefit in terms of cold symptoms or getting colds.” See: Cowling, B. et al. (2010) “Face masks to prevent transmission of influenza virus: A systematic review,” Epidemiology and Infection, 138(4), 449-456. https://www.cambridg...s-a-systematic- review/64D368496EBDE0AFCC6639CCC9D8BC05
 
"None of the studies reviewed showed a benefit from wearing a mask, in either HCW or community members in households (H). See summary Tables 1 and 2 therein. See: bin-Reza et al. (2012) “The use of masks and respirators to prevent transmission of influenza: a systematic review of the scientific evidence,” Influenza and Other Respiratory Viruses 6(4), 257–267. https://onlinelibrar...59.2011.00307.x
 
“There were 17 eligible studies. None of the studies established a conclusive relationship between mask/respirator use and protection against influenza infection.” See: Smith, J.D. et al. (2016) “Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis,” CMAJ Mar 2016 https://www.cmaj.ca/content/188/8/567
 
“We identified six clinical studies. In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection, (b) influenza-like illness, or © reported work-place absenteeism.” See: Offeddu, V. et al. (2017) “Effectiveness of Masks and Respirators Against Respiratory Infections in Healthcare Workers: A Systematic Review and Meta-Analysis,” Clinical Infectious Diseases, Volume 65, Issue 11, 1 December 2017, Pages 1934–1942, https://academic.oup...11/1934/4068747
 
“Self-reported assessment of clinical outcomes was prone to bias. Evidence of a protective effect of masks or respirators against verified respiratory infection (VRI) was not statistically significant”; as per Fig. 2c therein. See: Radonovich, L.J. et al. (2019) “N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel: A Randomized Clinical Trial,” See: JAMA. 2019; 322(9): 824–833. https://jamanetwork....article/2749214
 
“Among 2862 randomized participants, 2371 completed the study and accounted for 5180 HCW-seasons. Among outpatient health care personnel, N95 respirators vs medical masks as worn by participants in this trial resulted in no significant difference in the incidence of laboratory-confirmed influenza.” See: Long, Y. et al. (2020) “Effectiveness of N95 respirators versus surgical masks against influenza: A systematic review and meta-analysis,” See: J Evid Based Med. 2020; 1- 9. https://onlinelibrar...1111/jebm.12381

Edited by caliban, 18 July 2020 - 01:56 PM.
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#52 gamesguru

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Posted 18 July 2020 - 01:07 PM

Sit on the edge of your seat no longer.

 

Here are some sources to the extensive scientific literature that establishes that wearing masks is pointless in preventing viral spread:
 
Jacobs, J. L. et al. (2009) “Use of surgical face masks to reduce the incidence of the common cold among health care workers in Japan: A randomized controlled trial,” See: American Journal of Infection Control, Volume 37, Issue 5, 417 – 419. https://www.ncbi.nlm...pubmed/19216002

 

It however only requires them wear the mask at work, and it is only a surgical mask which are not very effective.  They could have easily contract the cold at home or the coffee shop.  The sick patients in the hospital were not wearing masks, so the protection conferred was not both ways.  We already know that is not very effective.

 

The number of layers used also helps stop the 0.3 micron tricky zone,

 

A single ply mask is likely less effective than a tight-fitting three layer fabric contraption.

Filteration_Collection_Mechanisms.png

Small particles zigzag due to Brownian motion, and are easily captured. Large particles get strained out, or have too much inertia to turn, and hit a fiber. Mid-size particles follow flowlines and are more likely to get through the filter; the hardest size to filter is 0.3 microns diameter.[12]
 

 

 

“N95-masked health-care workers (HCW) were significantly more likely to experience headaches. Face mask use in HCW was not demonstrated to provide benefit in terms of cold symptoms or getting colds.” See: Cowling, B. et al. (2010) “Face masks to prevent transmission of influenza virus: A systematic review,” Epidemiology and Infection, 138(4), 449-456. https://www.cambridg...s-a-systematic- review/64D368496EBDE0AFCC6639CCC9D8BC05

Again, just suggesting they are not effective one-way but need to be worn both ways.  Anyone watching cable news would have heard this peculiar fact coming from the media in March.

 

There is some evidence to support the wearing of masks or respirators during illness to protect others, and public health emphasis on mask wearing during illness may help to reduce influenza virus transmission. There are fewer data to support the use of masks or respirators to prevent becoming infected. Further studies in controlled settings and studies of natural infections in healthcare and community settings are required to better define the effectiveness of face masks and respirators in preventing influenza virus transmission.

 

"None of the studies reviewed showed a benefit from wearing a mask, in either HCW or community members in households (H). See summary Tables 1 and 2 therein. See: bin-Reza et al. (2012) “The use of masks and respirators to prevent transmission of influenza: a systematic review of the scientific evidence,” Influenza and Other Respiratory Viruses 6(4), 257–267. https://onlinelibrar...59.2011.00307.x

 

Nothing but a critical review of the literature, which a paragraph after what you posted surmises this:

 

Some evidence suggests that mask use is best undertaken as part
of a package of personal protection especially hand hygiene. The
effectiveness of masks and respirators is likely linked to early,
consistent and correct usage.

 

“There were 17 eligible studies. None of the studies established a conclusive relationship between mask/respirator use and protection against influenza infection.” See: Smith, J.D. et al. (2016) “Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis,” CMAJ Mar 2016 https://www.cmaj.ca/content/188/8/567

 

Another dubious review with small sample size (N=6) and extremely wide confidence intervals [influenza-like illness (RCTs: OR 0.51, 95% CI 0.19–1.41)], which nevertheless again confirms the benefit of good, quality N95 masks :sleep:

 

Although N95 respirators appeared to have a protective advantage over surgical masks in laboratory settings, our meta-analysis showed that there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks in protecting health care workers against transmissible acute respiratory infections in clinical settings.

 

“We identified six clinical studies. In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection, (b) influenza-like illness, or © reported work-place absenteeism.” See: Offeddu, V. et al. (2017) “Effectiveness of Masks and Respirators Against Respiratory Infections in Healthcare Workers: A Systematic Review and Meta-Analysis,” Clinical Infectious Diseases, Volume 65, Issue 11, 1 December 2017, Pages 1934–1942, https://academic.oup...11/1934/4068747

 

Nothing but a positive result, suggesting we wear masks lol.

 

This systematic review and meta-analysis supports the use of respiratory protection. However, the existing evidence is sparse and findings are inconsistent within and across studies.

 

“Self-reported assessment of clinical outcomes was prone to bias. Evidence of a protective effect of masks or respirators against verified respiratory infection (VRI) was not statistically significant”; as per Fig. 2c therein. See: Radonovich, L.J. et al. (2019) “N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel: A Randomized Clinical Trial,” See: JAMA. 2019; 322(9): 824–833. https://jamanetwork....article/2749214

 

Again no distinction is made between groups "always" and "sometimes" wearing their mask.  Masks are the more effective the more often they are worn out.  If a study is carelessly lumping together the most diligent with the most lackadaisical, it is lacking in scientific methodology.

 

So just not a very insightful meta-analysis in this case.

 

“Among 2862 randomized participants, 2371 completed the study and accounted for 5180 HCW-seasons. Among outpatient health care personnel, N95 respirators vs medical masks as worn by participants in this trial resulted in no significant difference in the incidence of laboratory-confirmed influenza.” See: Long, Y. et al. (2020) “Effectiveness of N95 respirators versus surgical masks against influenza: A systematic review and meta-analysis,” See: J Evid Based Med. 2020; 1- 9. https://onlinelibrar...1111/jebm.12381

 

Again just small meta-analysis (N=6), with shit confidence intervals.  Certainly an interesting result, but not to be too heavily weight against contrary findings.

 

There were no statisti-
cally significant differences in preventing laboratory-confirmed influenza (RR = 1.09, 95% CI 0.92-
1.28, P > .05), laboratory-confirmed respiratory viral infections (RR = 0.89, 95% CI 0.70-1.11),
laboratory-confirmed respiratory infection (RR = 0.74, 95% CI 0.42-1.29) and influenzalike ill-
ness (RR = 0.61, 95% CI 0.33-1.14) using N95 respirators and surgical masks. Meta-analysis indi-
cated a protective effect of N95 respirators against laboratory-confirmed bacterial colonization
(RR = 0.58, 95% CI 0.43-0.78).

 

My conclusion is there is no reason to suggest masks don't help, and further that there is no reason to wish that this were false.

 

-----------------------------------------------------

-----------------------------------------------------

 

Let's now take a look the other side of the coin, and see some of the studies I read (as early as April or May) that convinced me wearing a mask was likely a wise move.

 

A few of these are preview releases, accepted manuscripts awaiting peer-review.. but overall they seem to suggest the cautious attitude of wearing masks to me.

 

Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population

Marianne van der Sande1*, Peter Teunis1,2, Rob Sabel3
1 National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands, 2 Hubert Department of Global Health, Rollins School of Public Health, Emory
University, Atlanta, Georgia, United States of America, 3 Netherlands Organisation for Applied Scientific Research (TNO), Rijswijk, Netherlands


     Abstract


     Background: Governments are preparing for a potential influenza pandemic. Therefore they need data to assess the
     possible impact of interventions. Face-masks worn by the general population could be an accessible and affordable
     intervention, if effective when worn under routine circumstances.

     Methodology: We assessed transmission reduction potential provided by personal respirators, surgical masks and home-
     made masks when worn during a variety of activities by healthy volunteers and a simulated patient.

     Principal Findings: All types of masks reduced aerosol exposure, relatively stable over time, unaffected by duration of wear
     or type of activity, but with a high degree of individual variation. Personal respirators were more efficient than surgical
     masks, which were more efficient than home-made masks. Regardless of mask type, children were less well protected.
     Outward protection (mask wearing by a mechanical head) was less effective than inward protection (mask wearing by
     healthy volunteers).

     Conclusions/Significance: Any type of general mask use is likely to decrease viral exposure and infection risk on a
     population level, in spite of imperfect fit and imperfect adherence, personal respirators providing most protection. Masks
     worn by patients may not offer as great a degree of protection against aerosol transmission.




Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis

Derek K Chu, Elie A Akl, Stephanie Duda, Karla Solo, Sally Yaacoub, Holger J Schünemann, on behalf of the COVID-19 Systematic Urgent Review
Group Effort (SURGE) study authors*

Summary

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19 and is spread person
to person through close contact. We aimed to investigate the effects of physical distance, face masks, and eye
protection on virus transmission in health-care and non-health-care (eg, community) settings.

Methods We did a systematic review and meta-analysis to investigate the optimum distance for avoiding person
to person virus transmission and to assess the use of face masks and eye protection to prevent transmission of viruses.

We obtained data for SARS-CoV-2 and the betacoronaviruses that cause severe acute respiratory syndrome, and
Middle East respiratory syndrome from 21 standard WHO-specific and COVID-19-specific sources. We searched
these data sources from database inception to May 3, 2020, with no restriction by language, for comparative studies
and for contextual factors of acceptability, feasibility, resource use, and equity. We screened records, extracted data,
and assessed risk of bias in duplicate. We did frequentist and Bayesian meta-analyses and random-effects metaregressions.
We rated the certainty of evidence according to Cochrane methods and the GRADE approach. This study is registered with PROSPERO, CRD42020177047.

Findings Our search identified 172 observational studies across 16 countries and six continents, with no randomised
controlled trials and 44 relevant comparative studies in health-care and non-health-care settings (n=25 697 patients).
Transmission of viruses was lower with physical distancing of 1 m or more, compared with a distance of less than 1 m
(n=10 736, pooled adjusted odds ratio [aOR] 0·18, 95% CI 0·09 to 0·38; risk difference [RD] –10·2%, 95% CI
–11·5 to –7·5; moderate certainty); protection was increased as distance was lengthened (change in relative risk
[RR] 2·02 per m; pinteraction=0·041; moderate certainty). Face mask use could result in a large reduction in risk of
infection (n=2647; aOR 0·15, 95% CI 0·07 to 0·34, RD –14·3%, –15·9 to –10·7; low certainty), with stronger
associations with N95 or similar respirators compared with disposable surgical masks or similar (eg, reusable
12–16-layer cotton masks; pinteraction=0·090; posterior probability >95%, low certainty). Eye protection also was associated
with less infection (n=3713; aOR 0·22, 95% CI 0·12 to 0·39, RD –10·6%, 95% CI –12·5 to –7·7; low certainty).
Unadjusted studies and subgroup and sensitivity analyses showed similar findings.

Interpretation The findings of this systematic review and meta-analysis support physical distancing of 1 m or more
and provide quantitative estimates for models and contact tracing to inform policy. Optimum use of face masks,
respirators, and eye protection in public and health-care settings should be informed by these findings and contextual
factors. Robust randomised trials are needed to better inform the evidence for these interventions, but this systematic
appraisal of currently best available evidence might inform interim guidance.



Accepted manuscript
Surgical mask partition reduces the risk of non-contact transmission in a golden Syrian hamster model for Coronavirus Disease 2019 (COVID-19)

Jasper Fuk-Woo Chan, Shuofeng Yuan, Anna Jinxia Zhang, Vincent Kwok-Man Poon, Chris Chung-Sing Chan, Andrew Chak-Yiu Lee, Zhimeng Fan, Can Li, Ronghui Liang, Jianli Cao ... Show more
Clinical Infectious Diseases, ciaa644, https://doi.org/10.1093/cid/ciaa644
Published: 30 May 2020


Background

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is believed to be mostly transmitted by medium-to-large sized respiratory droplets although airborne transmission is theoretically possible in healthcare settings involving aerosol-generating procedures. Exposure to respiratory droplets can theoretically be reduced by surgical mask usage. However, there is a lack of experimental evidence supporting surgical mask usage for prevention of COVID-19.
Methods

We used a well-established golden Syrian hamster SARS-CoV-2 model. We placed SARS-CoV-2-challenged index hamsters and naïve hamsters into closed system units each comprising two different cages separated by a polyvinyl chloride air porous partition with unidirectional airflow within the isolator. The effect of a surgical mask partition placed in between the cages was investigated. Besides clinical scoring, hamster specimens were tested for viral load, histopathology, and viral nucleocapsid antigen expression.

Results

Non-contact transmission was found in 66.7% (10/15) of exposed naïve hamsters. Surgical mask partition for challenged index or naïve hamsters significantly reduced transmission to 25% (6/24, P=0.018). Surgical mask partition for challenged index hamsters significantly reduced transmission to only 16.7% (2/12, P=0.019) of exposed naïve hamsters. Unlike the severe COVID-19 manifestations of challenged hamsters, infected naïve hamsters had lower clinical scores, milder histopathological changes, and lower viral nucleocapsid antigen expression in respiratory tract tissues.

Conclusions

SARS-CoV-2 could be transmitted by respiratory droplets or airborne droplet nuclei in the hamster model. Such transmission could be reduced by surgical mask usage, especially when masks were worn by infected individuals.



 

Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic?

Objective

This study examined homemade masks as an alternative to commercial face masks.

 

Methods

Several household materials were evaluated for the capacity to block bacterial and viral aerosols. Twenty-one healthy volunteers made their own face masks from cotton t-shirts; the masks were then tested for fit. The number of microorganisms isolated from coughs of healthy volunteers wearing their homemade mask, a surgical mask, or no mask was compared using several air-sampling techniques.

 

Results

The median-fit factor of the homemade masks was one-half that of the surgical masks. Both masks significantly reduced the number of microorganisms expelled by volunteers, although the surgical mask was 3 times more effective in blocking transmission than the homemade mask.

 

Conclusion

Our findings suggest that a homemade mask should only be considered as a last resort to prevent droplet transmission from infected individuals, but it would be better than no protection. (Disaster Med Public Health Preparedness. 2013;0:1–6)



 

New study suggests wearing a face mask at home could help limit spread of COVID-19

Jackie Vandinther CTVNews.ca Digital Content Editor

@JackVanD Contact

Published Thursday, May 28, 2020 6:30PM EDT

 

TORONTO -- A new study has found that wearing a face mask in your home could help reduce the risk of spreading the coronavirus among those you live with.

 

Researchers from China, the U.S., and Australia carried out the retrospective cohort study between Feb. 28 and March 27, surveying 335 people from 124 families in Beijing, China, that had lived in the same house for at least four days prior and for more than a day after a person who had tested positive for COVID-19 started showing symptoms.

 

The researchers specifically focused on secondary cases of transmission of the virus, and how it spread in close contact situations, such as eating around a table or watching television, from someone in a household to other family members before the infected person became symptomatic.

 

Associations between wearing masks, washing hands, and social distancing practices, and risk of COVID-19 infection in public: a cohort-based case-control study in Thailand

Summary

Background. Effectiveness of personal protective measure against COVID-19 infection is largely
unknown.

Methods. We conducted a retrospective case-control study, using a cohort of contact tracing records in Thailand. A total of 1,050 asymptomatic contacts of COVID-19 patients between 1 and 31 March 2020 were retrospectively interviewed by phone about their protective measures against COVID-19 infection. Cases were defined as asymptomatic contacts who were diagnosed with COVID-19 by 21 April 2020. Multilevel mixed-effect logistic regression models were used

Findings. Overall, 211 (20%) were diagnosed with COVID-19 by 21 Apr 2020 (case group) while 839 (80%) were not (control group). Fourteen percent of cases (29/210) and 24% of controls (198/823) reported wearing either non-medical or medical masks all the time during the contact
period. Wearing masks all the time (adjusted odds ratio [aOR] 0.23; 95%CI 0.09-0.60) was independently associated with lower risk of COVID-19 infection compared to not wearing masks, while wearing masks sometimes (aOR 0.87; 95%CI 0.41-1.84) was not. Shortest distance of
contact >1 meter (aOR 0.15; 95%CI 0.04-0.63), duration of close contact ≤15 minutes (aOR 0.24; 95%CI 0.07-0.90) and washing hands often (aOR 0.33; 95%CI 0.13-0.87) were significantly associated with lower risk of infection. Sharing a cigarette (aOR 3.47; 95%CI 1.09-11.02) was
associated with higher risk of infection. Those who wore masks all the time were more likely to wash hands and practice social distancing. We estimated that if everyone wore a mask all the time, washed hands often, did not share a dish, cup or cigarette, maintained distances >1 meter and spent ≤15 minutes with close contacts, cases would have been reduced by 84%.

Interpretation. Our findings support consistently wearing masks, washing hands, and social distancing in public to protect against COVID-19 infections. Combining measures could substantially reduce infections in Thailand.


 

Absence of Apparent Transmission of SARS-CoV-2 from Two Stylists After Exposure at a Hair Salon with a Universal Face Covering Policy — Springfield, Missouri, May 2020

Weekly / July 17, 2020 / 69(28);930-932

On July 14, 2020, this report was posted online as an MMWR Early Release.

M. Joshua Hendrix, MD1; Charles Walde, MD2; Kendra Findley, MS3; Robin Trotman, DO4 (View author affiliations)

Among 139 clients exposed to two symptomatic hair stylists with confirmed COVID-19 while both the stylists and the clients wore face masks, no symptomatic secondary cases were reported; among 67 clients tested for SARS-CoV-2, all test results were negative. Adherence to the community’s and company’s face-covering policy likely mitigated spread of SARS-CoV-2.

What are the implications for public health practice?

As stay-at-home orders are lifted, professional and social interactions in the community will present more opportunities for spread of SARS-CoV-2. Broader implementation of face covering policies could mitigate the spread of infection in the general population.

 

Face Masks Considerably Reduce Covid-19 Cases in Germany

View ORCID ProfileTimo Mitze, Reinhold Kosfeld, View ORCID ProfileJohannes Rode, View ORCID ProfileKlaus Wälde
Abstract

We use the synthetic control method to analyze the effect of face masks on the spread of Covid-19 in Germany. Our identification approach exploits regional variation in the point in time when face masks became compulsory. Depending on the region we analyse, we find that face masks reduced the cumulative number of registered Covid-19 cases between 2.3% and 13% over a period of 10 days after they became compulsory. Assessing the credibility of the various estimates, we conclude that face masks reduce the daily growth rate of reported infections by around 40%.


Edited by caliban, 18 July 2020 - 02:02 PM.
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#53 Mind

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Posted 18 July 2020 - 04:47 PM

We do have some data on the U.S. about mask mandates. New Mexico was one of the first to institute a mandate, more than 2 months ago. The number of cases in that state have been steadily climbing over the last month, same as most other states.

 

South Korea has successfully dampened the spread of COVID, which many think has to do with masks, but they also have some of the most intrusive contact tracing (outside of China). However, they are still having outbreaks/flare-ups because people do not want to stay locked-down and wearing masks forever. People are getting-together clandestinely to worship, to party, etc.... There are some "health authorities" in the U.S. who are saying "don't worry, just wear masks for the nexty 4 to 8 weeks and everything will be better". South Korea shows, that once masks are mandated, they will never come off. South Koreans have been wearing masks for 7 months now, with no sign that it will ever end (the COVID rules/restrictions). They are even using light shows in the sky to remind everyone to constantly wear masks.

 

In contrast, Sweden's government gave guidance on how to stay safe and slow the spread, but did not mandate hardly anything. I would rather go the route of Sweden. It is a more human approach. It takes a more holistic view of the many aspects of health, society, and the economy.

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#54 gamesguru

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Posted 18 July 2020 - 05:26 PM

While it's true the above data from the US do not corroborate a benefit of masks, it is important to keep in mind the context and other variables.

 

Many people in my state, which has recently mandated masks, are doing one of the following:

  1. Not wearing a mask at all.
  2. Wearing the mask, but not over the nose, or not over their mouth, or both.
  3. Wearing a thin bandana or other pathetic single-ply mask.
  4. Getting "mitigation fatigue" and compensating the mask mandate by lessening other social distancing and returning to more of the economic activity and more of the usual things they enjoy.

The bottom line is mask may not be getting used properly, if at all, and other restrictions are being laxed in parallel with their mandate to befuddle any delineation of effect.

 

Yes, masks are a slippery slope and South Korea shows that once you mandate them it can be hard to go away.  But the benefits are multiplicative: opening the schools, bars and gyms, all without sending large waves of old people with COVID to the emergency room.

 

There's really nothing human about Sweden's approach.  They're nipping at Italy's heels in terms of per capita deaths.  They've let the rich prioritize their economy above the welfare of the masses, in a cover-up move which will only backfire long-term. They've lied to their people about the lethality and prevalence of a disease which will experience an inevitable resurgence in the Fall.


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#55 Florin

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Posted 18 July 2020 - 07:26 PM

We do have some data on the U.S. about mask mandates. New Mexico was one of the first to institute a mandate, more than 2 months ago. The number of cases in that state have been steadily climbing over the last month, same as most other states.
 
South Korea has successfully dampened the spread of COVID, which many think has to do with masks, but they also have some of the most intrusive contact tracing (outside of China). However, they are still having outbreaks/flare-ups because people do not want to stay locked-down and wearing masks forever. People are getting-together clandestinely to worship, to party, etc.... There are some "health authorities" in the U.S. who are saying "don't worry, just wear masks for the nexty 4 to 8 weeks and everything will be better". South Korea shows, that once masks are mandated, they will never come off. South Koreans have been wearing masks for 7 months now, with no sign that it will ever end (the COVID rules/restrictions). They are even using light shows in the sky to remind everyone to constantly wear masks.
 
In contrast, Sweden's government gave guidance on how to stay safe and slow the spread, but did not mandate hardly anything. I would rather go the route of Sweden. It is a more human approach. It takes a more holistic view of the many aspects of health, society, and the economy.


New Mexico's mask wearing compliance rate is less than 50%.

 

And as I mentioned in the other thread, the only common and consistent factor that Taiwan, Hong Kong, South Korea, and Japan share is mask wearing with high compliance. South Korea has done a lot of tracing but not Japan.

 

In contrast, Sweden's government has kind of approved of manslaughter by allowing everyone to spread around what amounts to poison gas. Manslaughter might be something that humans do, but it's not humane and should certainly not be legal.


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#56 osris

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Posted 19 July 2020 - 09:01 AM

It however only requires them wear the mask at work, and it is only a surgical mask which are not very effective.  They could have easily contract the cold at home or the coffee shop.  The sick patients in the hospital were not wearing masks, so the protection conferred was not both ways.  We already know that is not very effective.


 

 

 

Correct, surgical masks are not effective in preventing disease spread, as I pointed out in the thread on Covid-19. Hence, why their wide usage among the general public is ineffective.

 

However, when you say in post #33 in this thread:
 
"No one ever claimed masks "stop" disease from spreading."
 
You seem to be contradicting yourself from a statement you made in post #230 in the Covid-19 thread: 
 
"I would add anyone refusing to wear a mask is going against the scientific current." 


#57 osris

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Posted 19 July 2020 - 09:13 AM

It however only requires them wear the mask at work, and it is only a surgical mask which are not very effective.  They could have easily contract the cold at home or the coffee shop.  The sick patients in the hospital were not wearing masks, so the protection conferred was not both ways.  We already know that is not very effective.

 

The number of layers used also helps stop the 0.3 micron tricky zone,

 

A single ply mask is likely less effective than a tight-fitting three layer fabric contraption.

Filteration_Collection_Mechanisms.png

Small particles zigzag due to Brownian motion, and are easily captured. Large particles get strained out, or have too much inertia to turn, and hit a fiber. Mid-size particles follow flowlines and are more likely to get through the filter; the hardest size to filter is 0.3 microns diameter.[12]
 

 

 

Again, just suggesting they are not effective one-way but need to be worn both ways.  Anyone watching cable news would have heard this peculiar fact coming from the media in March.

 

There is some evidence to support the wearing of masks or respirators during illness to protect others, and public health emphasis on mask wearing during illness may help to reduce influenza virus transmission. There are fewer data to support the use of masks or respirators to prevent becoming infected. Further studies in controlled settings and studies of natural infections in healthcare and community settings are required to better define the effectiveness of face masks and respirators in preventing influenza virus transmission.

 

 

Nothing but a critical review of the literature, which a paragraph after what you posted surmises this:

 

Some evidence suggests that mask use is best undertaken as part
of a package of personal protection especially hand hygiene. The
effectiveness of masks and respirators is likely linked to early,
consistent and correct usage.

 

 

Another dubious review with small sample size (N=6) and extremely wide confidence intervals [influenza-like illness (RCTs: OR 0.51, 95% CI 0.19–1.41)], which nevertheless again confirms the benefit of good, quality N95 masks :sleep:

 

Although N95 respirators appeared to have a protective advantage over surgical masks in laboratory settings, our meta-analysis showed that there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks in protecting health care workers against transmissible acute respiratory infections in clinical settings.

 

 

Nothing but a positive result, suggesting we wear masks lol.

 

This systematic review and meta-analysis supports the use of respiratory protection. However, the existing evidence is sparse and findings are inconsistent within and across studies.

 

 

Again no distinction is made between groups "always" and "sometimes" wearing their mask.  Masks are the more effective the more often they are worn out.  If a study is carelessly lumping together the most diligent with the most lackadaisical, it is lacking in scientific methodology.

 

So just not a very insightful meta-analysis in this case.

 

 

Again just small meta-analysis (N=6), with shit confidence intervals.  Certainly an interesting result, but not to be too heavily weight against contrary findings.

 

There were no statisti-
cally significant differences in preventing laboratory-confirmed influenza (RR = 1.09, 95% CI 0.92-
1.28, P > .05), laboratory-confirmed respiratory viral infections (RR = 0.89, 95% CI 0.70-1.11),
laboratory-confirmed respiratory infection (RR = 0.74, 95% CI 0.42-1.29) and influenzalike ill-
ness (RR = 0.61, 95% CI 0.33-1.14) using N95 respirators and surgical masks. Meta-analysis indi-
cated a protective effect of N95 respirators against laboratory-confirmed bacterial colonization
(RR = 0.58, 95% CI 0.43-0.78).

 

My conclusion is there is no reason to suggest masks don't help, and further that there is no reason to wish that this were false.

 

-----------------------------------------------------

-----------------------------------------------------

 

Let's now take a look the other side of the coin, and see some of the studies I read (as early as April or May) that convinced me wearing a mask was likely a wise move.

 

A few of these are preview releases, accepted manuscripts awaiting peer-review.. but overall they seem to suggest the cautious attitude of wearing masks to me.

 


It however only requires them wear the mask at work, and it is only a surgical mask which are not very effective.  They could have easily contract the cold at home or the coffee shop.  The sick patients in the hospital were not wearing masks, so the protection conferred was not both ways.  We already know that is not very effective.

 

The number of layers used also helps stop the 0.3 micron tricky zone,

 

A single ply mask is likely less effective than a tight-fitting three layer fabric contraption.

Filteration_Collection_Mechanisms.png

Small particles zigzag due to Brownian motion, and are easily captured. Large particles get strained out, or have too much inertia to turn, and hit a fiber. Mid-size particles follow flowlines and are more likely to get through the filter; the hardest size to filter is 0.3 microns diameter.[12]
 

 

 

Again, just suggesting they are not effective one-way but need to be worn both ways.  Anyone watching cable news would have heard this peculiar fact coming from the media in March.

 

There is some evidence to support the wearing of masks or respirators during illness to protect others, and public health emphasis on mask wearing during illness may help to reduce influenza virus transmission. There are fewer data to support the use of masks or respirators to prevent becoming infected. Further studies in controlled settings and studies of natural infections in healthcare and community settings are required to better define the effectiveness of face masks and respirators in preventing influenza virus transmission.

 

 

Nothing but a critical review of the literature, which a paragraph after what you posted surmises this:

 

Some evidence suggests that mask use is best undertaken as part
of a package of personal protection especially hand hygiene. The
effectiveness of masks and respirators is likely linked to early,
consistent and correct usage.

 

 

Another dubious review with small sample size (N=6) and extremely wide confidence intervals [influenza-like illness (RCTs: OR 0.51, 95% CI 0.19–1.41)], which nevertheless again confirms the benefit of good, quality N95 masks :sleep:

 

Although N95 respirators appeared to have a protective advantage over surgical masks in laboratory settings, our meta-analysis showed that there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks in protecting health care workers against transmissible acute respiratory infections in clinical settings.

 

 

Nothing but a positive result, suggesting we wear masks lol.

 

This systematic review and meta-analysis supports the use of respiratory protection. However, the existing evidence is sparse and findings are inconsistent within and across studies.

 

 

Again no distinction is made between groups "always" and "sometimes" wearing their mask.  Masks are the more effective the more often they are worn out.  If a study is carelessly lumping together the most diligent with the most lackadaisical, it is lacking in scientific methodology.

 

So just not a very insightful meta-analysis in this case.

 

 

Again just small meta-analysis (N=6), with shit confidence intervals.  Certainly an interesting result, but not to be too heavily weight against contrary findings.

 

There were no statisti-
cally significant differences in preventing laboratory-confirmed influenza (RR = 1.09, 95% CI 0.92-
1.28, P > .05), laboratory-confirmed respiratory viral infections (RR = 0.89, 95% CI 0.70-1.11),
laboratory-confirmed respiratory infection (RR = 0.74, 95% CI 0.42-1.29) and influenzalike ill-
ness (RR = 0.61, 95% CI 0.33-1.14) using N95 respirators and surgical masks. Meta-analysis indi-
cated a protective effect of N95 respirators against laboratory-confirmed bacterial colonization
(RR = 0.58, 95% CI 0.43-0.78).

 

My conclusion is there is no reason to suggest masks don't help, and further that there is no reason to wish that this were false.

 

-----------------------------------------------------

-----------------------------------------------------

 

Let's now take a look the other side of the coin, and see some of the studies I read (as early as April or May) that convinced me wearing a mask was likely a wise move.

 

A few of these are preview releases, accepted manuscripts awaiting peer-review.. but overall they seem to suggest the cautious attitude of wearing masks to me.

 

The general thrust of your post, is that the articles I posted are wrong in saying that masks are not effective in preventing the spread of disease.

 

Yet, as I pointed out earlier, your objection to the articles contradicts what you say in post #33 in this thread:

 

"No one ever claimed masks "stop" disease from spreading."



#58 gamesguru

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Posted 19 July 2020 - 10:12 AM

?? Ok so now we've shifted away from the idea masks don't work back into black and white territory and simply trying to exemplify a "contradiction" i had invoked?  Well so what if i did, we're all human happens.  But I just think you're viewing things too black and white here.

 

They don't "stop" it.  But what is surprising to most is how a modest reduction in infection rates (say lowering the spread by 40-70%) can actually bring the epidemic under control (R0 < 1) while the disease continues to trivially spread for another few months or years all the while staggering lighter and lighter til at last no active cases remain.  In that sense the disease can continue to spread below the criticality threshold, while still ultimately going extinct.

 

What the MIT models have taught us however are how no model is perfect and nothing is certain.  We live in a world of billions of autonomous agents, presumably all dominated by the butterfly effect.  Anyone who thinks they can predict how things will happen is likely wrong, I can only say how things would conditionally proceed given common assumptions.  For example masks may "work" in Japan, but masks may mean something entirely different and less useful in the US.

 

But yes, masks do not prevent 100% of infections.  If you are in a room with other sick people and everyone is wearing masks, there is still an appreciable probability of you becoming sick.  It is just from an epidemiological perspective—not one of personal risk—that the rate of spread is insufficient to sustain active hosts while still not being absolutely stopped down to 0%.

 

So yeah, masks don't stop the spread, they may not even bring R0 < 1, but their utility in aiding the spread cannot be denied.

 

And when scenes like the one from Friday in Nasheville emerge of everyone partying in clubs and on the streets, with maybe 5% of them wearing masks, it becomes evident just how screwed America is. Not to mention the data is supposedly going through the HHS and White House before the CDC now, so pretty much expect to self-quarantine 14 days anywhere you travel (thanks to our tumbling reputation)


Edited by gamesguru, 19 July 2020 - 10:19 AM.

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#59 osris

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Posted 19 July 2020 - 02:02 PM

?? Ok so now we've shifted away from the idea masks don't work back into black and white territory and simply trying to exemplify a "contradiction" i had invoked?  Well so what if i did, we're all human happens.  But I just think you're viewing things too black and white here.

 

 

You spent two days disagreeing with me in the Covid-19 thread because I posted articles saying that masks don’t work. And you also posted a long and heavily linked post on this thread saying that masks do work.
 
And when I pointed out your contradictory statements about your view on masks, you say nonchalantly, “Well, what if I did”, and that I’m “viewing things too black and white”.
 
Yet, your vehement (and at times personally insulting) disagreement with me on the Covid-19 thread, was because you claimed that masks definitely do work, hence your long list of links to "prove" you were right.
 
All I can say to this, is that you were arguing with me in the other thread and here, for the sake of argument. This indicates a certain intellectual dishonesty. I use the word "intellectual" in your case tentatively.

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#60 osris

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Posted 19 July 2020 - 02:29 PM

Just thought I’d let people who are following this thread know that Gamesguru has retracted what he said about masks being effective. The moderators have shifted the mask debate to here:
 
 
In a reply to an admission by Gamesguru that surgical masks don’t work, I said in post #44 of the thread linked to:
 
“Correct, surgical masks are not effective in preventing disease spread, as I pointed out in the thread on Covid-19. Hence, why their wide usage among the general public is ineffective.
 
However, when you say in post #33 in this thread:
 
"No one ever claimed masks "stop" disease from spreading."
 
You seem to be contradicting yourself from a statement you made in post #230 in the Covid-19 thread: 
 
"I would add anyone refusing to wear a mask is going against the scientific current."”
 
He replied in post #46:
 
“Ok so now we've shifted away from the idea masks don't work back into black and white territory and simply trying to exemplify a "contradiction" i had invoked? Well so what if i did, we're all human happens. But I just think you're viewing things too black and white here.”
 
To which I replied in post #47:
 
“You spent two days disagreeing with me in the Covid-19 thread because I posted articles saying that masks don’t work. And you also posted a long and heavily linked post on this thread saying that masks do work.
 
And when I pointed out your contradictory statements about your view on masks, you say nonchalantly, “Well, what if I did”, and that I’m “viewing things too black and white”.
 
Yet, your vehement (and at times personally insulting) disagreement with me on the Covid-19 thread, was because you claimed that masks definitely do work, hence your long list of links to "prove" you were right.
 
All I can say to this, is that you were arguing with me in the other thread and here, for the sake of argument. This indicates a certain intellectual dishonesty. I use the word "intellectual" in your case tentatively.”
 
I mention all of this, only to let people know that Gamesguru is a slippery customer when it comes to positions he claims to hold. It appears he has wasted my time in arguing with me over this issue. 
 

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