You cite a study from the 1700's which only proves you have read nothing here or apparently anywhere else credible in the past 3 years.
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Coronavirus
- Thread starter Wenche
- Start date
PACEMD
Active Member
Right, that one came from the Salem Witch Trials. The question, as I understood, was if masked witches could effectively transmit spells. Unfortunately, those studies were not randomized, double-blind, placebo-controlled trials, until too late........
I take it you guys haven't read the 'study'?
It's a great work, we covered it extensively in engineering.
When I searched for your unlinked CDC review from 2020 I came up with this. Granted, it's from this year, so it's not quite what you were referencing.
Effectiveness of Face Mask or Respirator Use in Indoor ...
This report describes face mask or respirator effectiveness in helping protect against COVID-19 infection.
www.cdc.gov
Maybe you can share the 2020 study you are thinking about.
Note your graphic says not statistically significant? Or fictional for those who are scientists.
Study published on the CDC site, but not by the CDC, my bad:
wwwnc.cdc.gov
And the who study, where 10 out of 17 studies favoured no mask:
Study published on the CDC site, but not by the CDC, my bad:
Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings—Personal Protective and Environmental Measures
Pandemic Influenza—Personal Protective Measures
wwwnc.cdc.gov
And the who study, where 10 out of 17 studies favoured no mask:
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PACEMD
Active Member
Well, sure! If you buy into that whole germ theory of disease........
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Daniel in SD
(supervised)
Those people could be cautious in all sorts of other ways and more likely to be around similar people who try not spread covid. I know personally it was easy to wear an N95 whenever I was indoors but then once I went back to the office I stopped because wearing an N95 for 8 hours a day is not all that pleasant. Maybe people who don't have to spend a lot of time indoors are more likely to wear N95s when they do.When I searched for your unlinked CDC review from 2020 I came up with this. Granted, it's from this year, so it's not quite what you were referencing.
Effectiveness of Face Mask or Respirator Use in Indoor ...
This report describes face mask or respirator effectiveness in helping protect against COVID-19 infection.
View attachment 885558
Maybe you can share the 2020 study you are thinking about.
I believe they work but I think we need challenge trials.
You'd think someone could have rustled one up during a pandemic. The fact that they didn't serves as further proof they do nothing. Along with all the other proof.
There was 6 million masked failures in Japan in August. So presumably they recalled some batches, or the thousands of batches in use at the time. ANNND they didn't because they dont work, so for them not to work wasn't a surprise.
Good pick up! That graphic refers to the cloth mask group as being not statistically significant. Granted, that is hard to read and I had trouble making that out as well.Note your graphic says not statistically significant? Or fictional for those who are scientists.
Study published on the CDC site, but not by the CDC, my bad:
Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings—Personal Protective and Environmental Measures
Pandemic Influenza—Personal Protective Measures
And not coincidentally, the article you reference refers to face masks worn by the public which were likely cloth or procedure masks as well.
So yeah, cloth masks, and possibly procedure masks are not great for protection against aerosolized viruses.
I do think that there is the whole issue of 5 micron particles and the long held belief for the last 100 years that this was an iron clad threshold above which "airborne" did not occur, and thus the belief that you didn't need N95s for protection against Covid.
However, the few experts (they might be something like, engineers) in aerosol science have recently pointed out that that threshold is not a hard one at all. And very infectious particles can be airborne despite not meeting that size threshold. Something to do with density as well?
I suggest you read up on this to help understand why the science is evolving.
Actually, it is very hard to do a study on mask wearing, because nobody tolerates mask wearing 24 hours a day. Given that health care workers all go home and who knows what they do, despite what they say?
Why you think that the lack of a study that's nearly impossible to do proves anything at all is beyond me.
In the meantime, I am going to continue to wear my readily available N95.
PACEMD
Active Member
A systematic review reporting not finding definitive studies showing the effectiveness of certain types of masks is a very different thing from a claim that masks have been shown to be ineffective. Not even close and not at all a claim of the article. That's not how evidence works. If you could do a literature review of this article for us, the methodologies, and conclusions, and more importantly what you draw from this, what you are trying to imply, that would go a long way to clarifying the objective. Or perhaps I have misunderstood what you are trying to say........A systematic review is just that, a limited look at what we find just now with our hopefully reported, and verified methods........Note your graphic says not statistically significant? Or fictional for those who are scientists.
Study published on the CDC site, but not by the CDC, my bad:
Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings—Personal Protective and Environmental Measures
Pandemic Influenza—Personal Protective Measures
Daniel in SD
(supervised)
Well, doing challenge trials is very tough ethically.
Clearly something was working in Japan before August. It could be that masks work but once the virus gets contagious enough you're going to get exponential growth. It's just simple math that it doesn't take a big increase in the reproduction rate to get a huge increase in the number of people infected.
I think you are spot on. We are also looking at how infectious a given variant is. Omicron is far more infectious than the native strain was, so you are going to see breakthrough infections despite equal protective measures.
I agree it would be wonderful to have controlled prospective trials, but I am not going to volunteer to participate in one on a SARS virus, thank you!
PACEMD
Active Member
Please do the work to show us how you concluded these influenza "studies favored no mask"........and the relation to covid and other virus transmissions........
If masks are effective at 83% like the CDC claim, then it would be piss easy to show that in a study. And the 27 studies reviewed by the CDC published and WHO wouldn't have any that show the opposite. The WHO review had 10 out of 17 showing negative impact of masks. How the hell does that happen if they're effective? Someone is telling porkies.
With regard to the science and engineering, this is why I referenced Bernoulli. Firstly Stokes law shows that the droplet size hangs in the air for days, ie that the normal turbulence of the air is enough to suspend it almost indefinitely. Then Bernoulli shows that without a perfect seal they're functionally useless. (I'm sure everyone shaves before using them) Then industrial hygenists tell us that an N95 can pass 1.8% of the <1µm particles. The virus is 0.1µm, and can be functionally transmissive in particles of 0.3µm. a full three fold smaller than the 1.8%.
But even when you show the engineering and the lack of evidence, people still have faith. But I'm supportive, like I said earlier, if you can mask harder than the thousands of people in the studies, then you go for it.
The chap above who wanted a force ventilated respirator in jest was the only one making a serious attempt at finding a solution. That's the PPE they wear in the virology labs, if N95s worked I'm sure they'd wear them, they're certainly cheaper.
On the bit on the bottom, if PPE works why the need for all the other stuff: "airflow patterns, ventilation, filtration, and safe airborne disinfection,"
Daniel in SD
(supervised)
I thought that the performance gets better as the particle size gets smaller? The 95% is for 0.3um which is the worst case, it's better for both smaller and larger particles.
If N95's really don't work wouldn't there have been near 100% infection rates for doctors working with COVID patients?
Nope, performance is on a log scale typically, finer is always worse. But it's not that they don't do anything, it's whether it's enough see below:
Feels like people have forgotten that they have an immune system, though I have heard of nurses who have had it 6 times. But that's getting a bit CDC of me with anecdata.
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AlanSubie4Life
Efficiency Obsessed Member
You realize it matters how much virus you inhale, right? It’s not like you inhale thousands of virus particles and then you automatically get infected! It also matters how rapidly you inhale them!
Dose-response relationship.
This is not really that complicated to figure out. (And you can see this points to using N95 too.)
I agree there should be challenge trials though! No reason not to.
Many of the studies do not show good strong signals of efficacy because no one wears masks in the studies.
I think you have moved the goalpost from:
"There’s 100 years of science that says masks aren’t effective."
to:
Thing is, we also know that there appears to be more than a simple plus/minus of exposure to whether or not someone becomes ill.
There is also dose, length of exposure, individual susceptibility, and the infectivity of the viral particle/variant among others. And these may be moving targets as a virus mutates. Which, again, makes clinical controlled trials more difficult.
If the mask just reduces the exposure some, it may be and probably often is enough to prevent clinical illness. It might allow, as you clearly recognize, the exposed person's immune system to clean up without clinical illness and very possibly blessing them with a degree of immunity.
It needn't be all or nothing. It's not as if one viral particle and you are in the ICU.
At any rate, I will happily grant you that a procedure mask is not going to do much in a high particle environment, which is why we wear PAPRs or N95s in those environments when we know. I am sure many nurses caught Covid because they were given procedure masks and were exposed before they suspected a given patient had covid. And yes, there are breakthroughs in any event.
And, to make things more fun, a noninconsequential percentage of people don't have the right ACE2 receptors for the virus to take hold of, so they are highly resistant and make studies harder, since we don't know for sure who they are, just that they exist.
Anecdotally but with assurance, I can tell you that my partners who caught it (we've all been real careful to wear N95s rather than the company provided procedure masks) did so from their partners or kids, who all came home with it first. We are a small place, and it's a small sample size, but...
"There’s 100 years of science that says masks aren’t effective."
to:
And you appear to be saying that because there isn't 100% reduction of penetration then they can't be effective at all, unless you have changed your story.
Thing is, we also know that there appears to be more than a simple plus/minus of exposure to whether or not someone becomes ill.
There is also dose, length of exposure, individual susceptibility, and the infectivity of the viral particle/variant among others. And these may be moving targets as a virus mutates. Which, again, makes clinical controlled trials more difficult.
If the mask just reduces the exposure some, it may be and probably often is enough to prevent clinical illness. It might allow, as you clearly recognize, the exposed person's immune system to clean up without clinical illness and very possibly blessing them with a degree of immunity.
It needn't be all or nothing. It's not as if one viral particle and you are in the ICU.
At any rate, I will happily grant you that a procedure mask is not going to do much in a high particle environment, which is why we wear PAPRs or N95s in those environments when we know. I am sure many nurses caught Covid because they were given procedure masks and were exposed before they suspected a given patient had covid. And yes, there are breakthroughs in any event.
And, to make things more fun, a noninconsequential percentage of people don't have the right ACE2 receptors for the virus to take hold of, so they are highly resistant and make studies harder, since we don't know for sure who they are, just that they exist.
Anecdotally but with assurance, I can tell you that my partners who caught it (we've all been real careful to wear N95s rather than the company provided procedure masks) did so from their partners or kids, who all came home with it first. We are a small place, and it's a small sample size, but...
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