Recent review of the studies on using masks to prevent the transmission of Covid-19.

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RyanB said:
My opinion is - I don’t understand why mask wearing has become so hostile and divisive. So many people seem to like going against the grain for the sake of making a statement and just being outright difficult. It hurts nobody and can only help. Proper mask wearing DOES reduce the spread of airborne viruses and there’s plenty of data to support it.
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On the last bit I will I have to disagree and I think that was sort of the point of this review. Considered objectively overall, the data to support cloth mask wearing by the general public is rather mixed.

And indeed those authors seem to have ignored MacIntyre et al 2016 which showed that health care workers wearing masks had a higher rate of infection. I don’t view that as determinative, but it is one part of the data that says the case is not so clear.
 
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Cap'n Jack said:
I don't know what you are saying with that response. People wear a mask when they have to, in a store, maybe, and beyond that, no one really knows how much the population masks up outside of legal compulsion.
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There is some survey data by the New York Times on the level of compliance, if that is what you are driving at.

My non randomized observation is that there is a higher level of compliance than say back in April and that the level of compliance where legally required, such as in stores here in AZ, is quite high.
 
Llewtrah381 said:
I know I don’t need to wear a mask to protect myself or others but doing so helps others remember the communal importance of doing so, in the absence of anything better to do to stop this illness right now, until immunization is rolled out broadly.
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Thanks, that is an honest take on the situation. I have a somewhat different attitude in that I think our rights in general are being grossly eroded by our present government. So in this particular case, and given the over politicization of this issue and distortion
of the facts for political purposes on all sides, I think it important for me to speak out objectively about the facts.
 
PeterNSteinmetz said:
Thanks, that is an honest take on the situation. I have a somewhat different attitude in that I think our rights in general are being grossly eroded by our present government. So in this particular case, and given the over politicization of this issue and distortion
of the facts for political purposes on all sides, I think it important for me to speak out objectively about the facts.
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Or what you believe are the facts. I disagree about the erosion of rights. People were saying the same sort of stuff in 1918.
 
Cap'n Jack said:
Or what you believe are the facts. I disagree about the erosion of rights. People were saying the same sort of stuff in 1918.
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So you don’t think there are sort of outrageous distortions on both sides of the issue?


I was referring to the erosion of our rights in general, not just WRT COVID-19. However, that general phenomenon does influence my choices WRT mask mandates for COVID-19.
 
I think it's a little odd to quibble about masks, when there are other, more onerous restrictions. What if we could do everything we used to be able to do before, only masked?
 
PeterNSteinmetz said:
There is some survey data by the New York Times on the level of compliance, if that is what you are driving at.

My non randomized observation is that there is a higher level of compliance than say back in April and that the level of compliance where legally required, such as in stores here in AZ, is quite high.
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First, I don't think anyone here considers the New York Times a good source of data for this subject.
Second, we agree people comply with wearing a mask outside of places where legally compelled. One problem seems to be private gatherings. Some workplaces don't require masks, or require them only in limited circumstances. I suspect that people, most of the time, are in situations where they aren't compelled to wear masks. Some choose to wear them, some don't need to wear them, and some should wear them but choose not to in those situations. No one really knows what people do out of the public eye.
 
It does depend on where you live. Some places are much more restrictive than AZ and have a bigger issue, I agree. I feel bad for them.

There is almost no good evidence that lockdowns reduce mortality overall, at least here in the US. So that seems outrageous to me given the huge costs of such things. But that is of course a whole other subject.
 
PeterNSteinmetz said:
So you don’t think there are sort of outrageous distortions on both sides of the issue?
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I say the medical community consensus supports mask wearing. It's only a hardship to those who chose to make it one.

PeterNSteinmetz said:
I was referring to the erosion of our rights in general, not just WRT COVID-19. However, that general phenomenon does influence my choices WRT mask mandates for COVID-19.
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And you keep going political here. With respect to disease, people were saying the same thing in 1918
 
Cap'n Jack said:
I realize you may not be able to get a good answer to this, but why do you think everyone has been wearing masks? I only see people wearing masks when they need to (at stores), but I have no idea what they do outside of that environment. Your postulate may be correct, or incorrect.
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Anecdotal. 99+% of the people I see are wearing masks. I presume the other ones have already had the virus.
 
PeterNSteinmetz said:
It does depend on where you live. Some places are much more restrictive than AZ and have a bigger issue, I agree. I feel bad for them.

There is almost no good evidence that lockdowns reduce mortality overall, at least here in the US. So that seems outrageous to me given the huge costs of such things. But that is of course a whole other subject.
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The US was never locked down. There were so many "essential businesses" I doubt we reached 50% lockdown.
 
bflynn said:
Anecdotal. 99+% of the people I see are wearing masks. I presume the other ones have already had the virus.
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Same here, but I only see them in places they are compelled to wear them. What happens when they aren't in a place where they need to wear one?
 
Cap'n Jack said:
One problem seems to be private gatherings. Some workplaces don't require masks, or require them only in limited circumstances. I suspect that people, most of the time, are in situations where they aren't compelled to wear masks. Some choose to wear them, some don't need to wear them, and some should wear them but choose not to in those situations. No one really knows what people do out of the public eye.
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I agree with you and the authors of the review that there are certain higher risk situations where using a mask that really works, like an N95, is likely wise. That is one of the reasons that my institute developed the adaptor for the 3M 6200 - so more people would be able to access that technology.

I notice that almost no mechanics that work on planes outside wear them, which is likely lower risk. Airplane cockpits are of course a different matter and higher risk in my view.

My primary concern, as may be obvious, had been with mask mandates. Both because of the insidious rights implications as well as the potential enablement of genuinely risky behavior where people over-estimate the value of a cloth mask.
 
Cap'n Jack said:
I say the medical community consensus supports mask wearing.
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I will have to disagree. If you looked at the actual scientific reviews (not commentaries or lay articles), the evidence is well described as mixed on whether asking the general public to wear cloth masks inhibits the spread of COVID-19.

I thought the review cited makes a pretty fair assessment based on the more recent evidence. Prior to that, the reviews, which are listed on my medical interest page at http://steinmetz.org/peter/Medical were about 50/50 split.

If you want we can discuss those reviews and the articles underlying them in detail. But I gather you don’t really feel this is the appropriate forum.

But I really do not think it accurate to say there is a clear scientific consensus on this point.

It may be uncomfortable, but the evidence is just not that clear presently on this specific question.
 
Cap'n Jack said:
The US was never locked down. There were so many "essential businesses" I doubt we reached 50% lockdown.
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There was about a 30% drop in mobility measures per both Apple and Google which preceded the initial phase of lockdown orders by about 3 weeks.

The initial lockdown orders were significantly correlated with a rise in mortality when adjusting for population and the timing of both the orders and the initial cases on a per state basis in the US. But not in the way one would expect - the states with lockdown orders had HIGHER rates of mortality attributed to COVID-19.

One could interpret that to mean lockdowns caused more deaths, though I am inclined to think there is some other uncontrolled independent variable.
 
PeterNSteinmetz said:
My primary concern, as may be obvious, had been with mask mandates. Both because of the insidious rights implications as well as the potential enablement of genuinely risky behavior where people over-estimate the value of a cloth mask.
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Let’s be honest here: do I wear a shirt and pants and undies out in public for my own well-being? Generally, no - unless it’s really, really sunny and certain parts could get burned. I wear them mainly so I don’t traumatize some poor kid with my hairy, pasty-white belly - and other parts - being exposed. Wearing a mask in that context makes me think of the Mission Impossible movie: “‘This will be difficult.’ ‘Hunt, this is Mission Impossible; “difficult” should be a walk in the park for you’”

Heck - I wash my hands after going boom-boom not because I know I have some intestinal disease I don’t want to pass on but because it’s the right thing to do as part of something bigger than me.

Why has this gotten so politicized?!? Why are we trying to pick the fly poop out of the pepper by over-analyzing the medical literature? Sheesh...

Masks seem to help. Probably more than wearing underwear.

Sorry - I’ll get off my soapbox. Hopefully without tripping...

Just being snarky in a VERY general sort of way. Nothing personal intended at all.
 
Llewtrah381 said:
Masks seem to help. Probably more than wearing underwear.
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Well, that seriously depends. If your jeans get wet with no underwear, you're in for one heck of a rash. You might be walking bo-legged for at least a day or two. Plus, just keeping your clothes cleaner. Underwear has it's use.

Personally, I wear clothes outside because I don't want to get arrested. If there were no laws compelling it, I'm not sure how much I would wear. I'll let that image sink in...you're welcome.
 
Llewtrah381 said:
Why has this gotten so politicized?!?
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We should probably limit this political aspect of the discussion as that is not permitted on PoA and will result in a lock. PM me if you would like to discuss further why I take it as a political issue. I appreciate your insights and opinion.
 
PeterNSteinmetz said:
Here is a recent review in the New England Journal of Medicine of the studies on using masks to prevent the transmission of Covid-19. I think they did a fairly good job of summarizing the strengths and weaknesses of the evidence and the tradeoffs in terms of public policy.

https://www.acpjournals.org/doi/10.7326/M20-6625

As they note, there is only one randomized study which showed no significant decrease in infection rate from wearing surgical masks for the wearer. The evidence for source control, that is, an effect on preventing spread to others, is either based on observational studies (which can have many confounds) or in-vitro studies of droplet dynamics (which do not account for human behavior in wearing masks).

As also noted by the authors, it is almost impossible to do a proper randomized study on source control. To the extent that is true, it implies that the source control justification for masks is essentially a non-falsifiable hypothesis.

Overall, the authors believe that the potential benefits outweigh the harms in terms of their value judgments. In terms of the controversy over mask mandates, they also note that "However, mask mandates involve a tradeoff with personal freedom, so such policies should be pursued only if the threat is substantial and mitigation of spread cannot be achieved through other means."

Thus, in terms of the scientific question, mixed evidence which may not be resolvable in the near future.

The policy question of course is, are people justified in forcing others to wear masks through executive orders and laws, given such mixed evidence? Not a question I will comment on here, but that is the political or policy question.

(My understanding of the current PoA rules is that this type of scientific post on Covid-19 is permitted given the current pandemic; but if I am mistaken, I trust the MC will delete.)
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From that paper's "conclusions" section:

"Evidence that the virus can be airborne (and therefore be inhaled) and that masking policies, when effectively delivered, save lives is now strong."

"[W]e recommend that the public wear masks or face coverings..."

The most fascinating part of the story is how you can continually take papers and draw conclusions from them that are totally opposite to the paper's own authors.
 
Cap'n Jack said:
First, I don't think anyone here considers the New York Times a good source of data for this subject....
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That's a pretty sweeping generalization. As for this survey, I would need to see their methodology before forming an opinion on its validity.
 
RyanB said:
My opinion is - I don’t understand why mask wearing has become so hostile and divisive. So many people seem to like going against the grain for the sake of making a statement and just being outright difficult. It hurts nobody and can only help. Proper mask wearing DOES reduce the spread of airborne viruses and there’s plenty of data to support it.
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It’s not about the mask.

Edit: mask mandates do hurt society. Nothing is free.
 
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RyanB said:
My opinion is - I don’t understand why mask wearing has become so hostile and divisive. So many people seem to like going against the grain for the sake of making a statement and just being outright difficult. It hurts nobody and can only help. Proper mask wearing DOES reduce the spread of airborne viruses and there’s plenty of data to support it.
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Tarheelpilot said:
It’s not about the mask.
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For some people, it seems to be.
 
dmspilot said:
The most fascinating part of the story is how you can continually take papers and draw conclusions from them that are totally opposite to the paper's own authors.
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As I think I’ve noted on this forum in the past, for any given issue, there seem to be people on both sides who will use any given piece of info like a drunk uses a lamp post: more for support than illumination.
 
dmspilot said:
From that paper's "conclusions" section:

"Evidence that the virus can be airborne (and therefore be inhaled) and that masking policies, when effectively delivered, save lives is now strong."

"[W]e recommend that the public wear masks or face coverings..."

The most fascinating part of the story is how you can continually take papers and draw conclusions from them that are totally opposite to the paper's own authors.
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I don't know if I am disagreeing with the authors much here. For example, please see the part after the ellipsis which you omitted and which limits the conditions under which they recommend the public use masks. Pretty much what I said above. Use them in high risk situations.

Please also see the key points summary which disagrees with the one statement from the discussion which you quoted above. Sometimes the authors of papers make a variety of different statements, some of which, if taken in isolation, will appear to have a different meaning than what they intended overall.

As I noted above, rather than dithering about the specific meaning in one sentence or word or another, I usually find it best to read the whole paper to understand the authors’ whole meaning. Considered as a whole, I think it is well described by their 5 key points at the top of paper in terms of the level of scientific certainty.
 
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Quoting someone:
RATE of infection is not the same as SEVERITY of infection. My, again subjective, premise is that being exposed to, say, 100 virus particles because a mask blocked 900 others is going to give me a less severe infection than being exposed to all 1,000 particles. I may indeed get an infection with the 100 but it will likely be less severe than if I was exposed to 1000 because my body can hopefully better manage the 100. This is all simplistic analogies to help others understand the premise (and not at all meaning to sound condescending with that). Getting exposed to only 100 sparks from a sparkler is less likely to lead to a severe fire than being exposed to 1,000 sparks. Both may cause “a fire” but one is typically easier to put out than the other.
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This is nonsense. The premise is the number virus particles you are exposed to is a finite quantity. As if the virus does not reproduce in the host. Find me a virologist who agrees with and I'll eat that hat I have left over from the other thread. Sure would be nice if it were true, though.
 
Ravioli said:
This is nonsense. The premise is the number virus particles you are exposed to is a finite quantity. As if the virus does not reproduce in the host. Find me a virologist who agrees with and I'll eat that hat I have left over from the other thread. Sure would be nice if it were true, though.
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Agreed that the initial viral load being correlated with the likelihood of getting sick is better established. But I thought I had read some reports on both sides of this issue of correlation with disease severity. This article may be of interest: https://www.sciencealert.com/does-t...-are-exposed-to-determine-how-sick-you-ll-get.

It states that basically we don't know if initial viral load affects disease severity. Please note this is a secondary source and from early on. A quick search of scholar.google.com did not reveal any more detailed recent studies, so perhaps it is not a viable current idea.
 
Ravioli said:
This is nonsense. The premise is the number virus particles you are exposed to is a finite quantity. As if the virus does not reproduce in the host. Find me a virologist who agrees with and I'll eat that hat I have left over from the other thread. Sure would be nice if it were true, though.
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If you’re saying MY premise is “...the number of virus particles you’re exposed to is a finite quantity”, that is inaccurate. My premise is the masks reduce the number of particles I am exposed to when I’m wearing it (by blocking many of them from getting in my mouth/nose) and reduces the number I expose YOU to if I’m infected/contagious (by blocking many of them from getting OUT of my mouth/nose). Didn’t say anything about some finite quantity - just tried to illustrate with some made-up numbers. That said, I probably should have said it gives me a better CHANCE of a less severe infection at the start.

I still think the hypothesis is sound - and it’s not something I personally made up to rationalize wearing a mask. It’s consistent with what’s seen in other infectious diseases (but not all). In fact, the third paragraph of the article cited by Peter above says:

“We know for some diseases that the dose of virus a person is exposed to will directly correlate with how severe the disease is. A good example of this is influenza.”
 
Why is the virus worse in California vs. an open state like Florida?
 
RyanB said:
My opinion is - I don’t understand why mask wearing has become so hostile and divisive. So many people seem to like going against the grain for the sake of making a statement and just being outright difficult. It hurts nobody and can only help. Proper mask wearing DOES reduce the spread of airborne viruses and there’s plenty of data to support it.
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I think some of it is about control, loss of control actually. You wanna eat out, you can’t because the restaurant is closed. You got no control over that. Ya wanna go see a ball game, you can’t, you got no control over that. You want to send your kids to school, you can’t, you got no control over that. But by gum by golly, I got control over whether or not I’m gonna wear a mask
 
Llewtrah381 said:
... My premise is the masks reduce the number of particles I am exposed to when I’m wearing it (by blocking many of them from getting in my mouth/nose) and reduces the number I expose YOU to if I’m infected/contagious (by blocking many of them from getting OUT of my mouth/nose). ... That said, I probably should have said it gives me a better CHANCE of a less severe infection at the start.
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Speculating on this a bit more it strikes me both things could essentially be true. It could be that the initial number of virions you are exposed to determines primarily the likelihood you will become ill and also have an effect on disease severity. This would be consistent with what we know about immune response.

If you receive less than a certain threshold number of virions, your immune system is able to mount a completely effective response and wipe out the virus. If you receive just a bit over that number, perhaps you mount a response and in some sense were infected, but it is tamped down quickly without much ill effect. And if you receive more than even another higher threshold, the virus is able to start geometric growth and you become fully ill, with the severity now determined by a number of other genetic and acquired health factors.

Would be a hard thing to prove in some sense without a lot of virus challenge experiments, which are difficult ethically. This is just my musings - I don't know of any hard papers to support this specifically in the case of Covid-19.
 
Checkout_my_Six said:
Why is the virus worse in California vs. an open state like Florida?
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Because there is a very significant portion of the population that 1) continues to have engage in family/social gatherings that produce an elevated risk of infection; and/or 2) lives in a crowded housing situation where effective isolation is essentially impossible, resulting in rapid spread of the virus within a household.

If we want to argue about the effectiveness of cloth masks, we should be asking why KN-95/N-95 masks haven't been massively manufactured/pushed out to the public for free/cheap. I'm fortunate that I can afford KN-95s and have an ample supply.
 
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