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

[Checkout_my_Six]

So, you're an advocate of home mask usage?

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.

 

[Jeff Oslick]

So, you're an advocate of home mask usage?

If you're living or visiting with family that may work or have visited a higher risk environment, yes. If you have someone in your home self-isolating due to a known or suspected exposure, then yes.

We're not getting out of this situation because there are far too many people who won't or can't take the needed measures to get the R0 below 1. Modest self-sacrifice in the name of making the perfect the enemy of the good is beyond the capacity of too many of our species.

 

[Lindberg]

We're not getting out of this situation because there are far too many people who won't or can't take the needed measures to get the R0 below 1.

The point is, we don't actually know what those measures are to any degree of scientific certainty. Even those advocating following the "science" only advocate for the science that matches their bisses.

Modest self-sacrifice in the name of making the perfect the enemy of the good is beyond the capacity of too many of our species.

Wow, that's some scary rhetoric considering the reality. Those demanding sacrifice should have a much higher burden than what they've met. Considering that many mask mandates and stay-at-home orders were put in place as "emergency orders" 6-9-12 months ago, the deadline to prove they're necessary and effective has expired. IMHO.

 

[Jeff Oslick]

Considering that many mask mandates and stay-at-home orders were put in place as "emergency orders" 6-9-12 months ago, the deadline to prove they're necessary and effective has expired. IMHO.

You can't determine if something is effective if there has been no effective enforcement. I don't find it at all unsurprising that California was doing reasonably well until Halloween. There were many inter-household gatherings that weekend, and I have little doubt that was what set off the current situation, though it surely would have happened on Thanksgiving if it hadn't happened on Halloween.

 

[Jeff Oslick]

Those demanding sacrifice should have a much higher burden than what they've met.

When it comes to leadership in this country/state/local, regardless of party, I don't disagree.

I am arguing for self-sacrifice, and I have walked-the-walk.

 

[Bob Noel]

Probably some truth to that as it seems to be where most people get it.

well, consider where people spend most of their time.

Kind of like most car accidents occurring close to home... not because that is necessarily more dangerous, but mostly because that's where people drive the most.

 

[Lindberg]

You can't determine if something is effective if there has been no effective enforcement. I don't find it at all unsurprising that California was doing reasonably well until Halloween. There were many inter-household gatherings that weekend, and I have little doubt that was what set off the current situation, though it surely would have happened on Thanksgiving if it hadn't happened on Halloween.

You think that might've had something to do with "two weeks to flatten the curve" turning into eight months, without any explanation? These are not unrelated occurrences. You can't convince people to upend their lives indefinitely if you can't convince them there's reason to.

 

[Jeff Oslick]

You think that might've had something to do with "two weeks to flatten the curve" turning into eight months, without any explanation? These are not unrelated occurrences. You can't convince people to upend their lives indefinitely if you can't convince them there's reason to.

California did "flatten the curve" from from August through October, while having limited indoor and outdoor dining and limited barber/salon services, open retail with masks and worker precautions, etc. It was largely private gatherings that did us in, then those folks spread it to their workplaces.

 

[Checkout_my_Six]

Ok....I'm home and wearing a mask.




But.....I am working with insulation on a bathroom project.....

 

[PeterNSteinmetz]

California did "flatten the curve" from from August through October, while having limited indoor and outdoor dining and limited barber/salon services, open retail with masks and worker precautions, etc. It was largely private gatherings that did us in, then those folks spread it to their workplaces.

I don’t know that one can clearly attribute the cause of the recent run-up like that. Most flu seasons follow this sort of course.

The reasons for the seasonality are presently debated but may include more time inside, colder temperatures, kids in school (though presumably not as big a factor this year).

Certainly gatherings is one reasonable hypothesis, but there may be other factors that are substantial contributions as well.

 

[Tarheelpilot]

Why is the virus worse in California vs. an open state like Florida?

Because God has been to California and his favorite restaurant was closed due to covid. He is vengeful.

 

[Matthew Rogers]

It’s not about the mask.

Edit: mask mandates do hurt society. Nothing is free.

Edit: mask mandates also save lives (or at least have a 50/50 chance according to the OP). Which is worse? Totally valid question. It is like the classic choice of crashing the school bus to avoid a single child on the road. Which do you choose?

Quoting someone:
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.

From mid September
https://www.medpagetoday.com/infectiousdisease/covid19/88692

Gandhi told MedPage Today that the viral inoculum, or the initial dose of virus that a patient takes in, is one likely determinant of ultimate illness severity. That's separate from patients' subsequent viral load, the level of replicating virus as measured by copies per mL.

 

[Palmpilot]

Inferring the effectiveness of government interventions against COVID-19

https://science.sciencemag.org/content/early/2020/12/15/science.abd9338.full

Abstract
Governments are attempting to control the COVID-19 pandemic with nonpharmaceutical interventions (NPIs). However, the effectiveness of different NPIs at reducing transmission is poorly understood. We gathered chronological data on the implementation of NPIs for several European, and other, countries between January and the end of May 2020. We estimate the effectiveness of NPIs, ranging from limiting gathering sizes, business closures, and closure of educational institutions to stay-at-home orders. To do so, we used a Bayesian hierarchical model that links NPI implementation dates to national case and death counts and supported the results with extensive empirical validation. Closing all educational institutions, limiting gatherings to 10 people or less, and closing face-to-face businesses each reduced transmission considerably. The additional effect of stay-at-home orders was comparatively small.​

 

[Palmpilot]

Flattening the curve worked — until it didn’t
The US started 2020 by “flattening the curve” — and never came up with a plan for what comes next.

https://www.vox.com/22180261/covid-19-coronavirus-social-distancing-lockdowns-flatten-the-curve

Excerpt:

The US did succeed at flattening the curve — at least at first. Businesses closed and most states issued stay-at-home orders, and later research concluded those lockdown measures helped prevent tens of millions of Covid-19 cases.

But America failed to take advantage of that window to ramp up its testing-and-tracing capabilities, and states quickly faced intense pressure to relax their policies to alleviate the economic costs of the shutdowns. Reopening began earlier than public health experts believed it should. The political will to impose new lockdowns had evaporated by the time cases spiked again.​

 

[Bob Noel]

It's so easy to find experts that run to the safe conservative positions.

 

[PeterNSteinmetz]

Edit: mask mandates also save lives (or at least have a 50/50 chance according to the OP). Which is worse? Totally valid question. It is like the classic choice of crashing the school bus to avoid a single child on the road. Which do you choose?

Exactly, whether to use a coercive government mandate in the presence of such mixed evidence is the key policy question.

And a political one which I won’t personally go into here per PoA policy.

 

[PeterNSteinmetz]

Flattening the curve worked — until it didn’t
The US started 2020 by “flattening the curve” — and never came up with a plan for what comes next.

https://www.vox.com/22180261/covid-19-coronavirus-social-distancing-lockdowns-flatten-the-curve

Excerpt:

The US did succeed at flattening the curve — at least at first. Businesses closed and most states issued stay-at-home orders, and later research concluded those lockdown measures helped prevent tens of millions of Covid-19 cases.
​

I don’t think the peer-reviewed literature is so crystal clear as Vox would represent here. Particularly regarding the effect of coercive government lockdowns.

Two things were going on initially. People began socially distancing voluntarily about 2-3 weeks before any lockdown orders, as shown by social mobility data. After the orders, they started resuming more normal travel, though I suspect that is just fatigue rather than caused by the orders.

Also at first testing was very limited and there was a strong correlation between number of tests and number of positive cases reported, particularly early on. (The lack of random population sampling really hurt us in tracking this.)

While the question of cases is quite confounded by increased testing capacity in that timeframe, what is clearer is that lockdowns initially had no significant effect on deaths attributed to COVID-19 in the US.

There is good data that things like staying away from people and using N95 masks work to prevent the spread of Covid-19. The effectiveness of coercive lockdowns and mask mandates are a different matter.​

 

[Everskyward]

Exactly, whether to use a coercive government mandate in the presence of such mixed evidence is the key policy question.

And a political one which I won’t personally go into here per PoA policy.

That's the whole point of why you brought up the subject. You have been there before. How many times have you written, "coercive government mandate" on this board? You want people to agree with you on policy, which is not able to be discussed here.

 

[Checkout_my_Six]

Why are you typing in large bold fonts?

 

[PeterNSteinmetz]

That's the whole point of why you brought up the subject. You have been there before. How many times have you written, "coercive government mandate" on this board? You want people to agree with you on policy, which is not able to be discussed here.

I understand that the policy can’t be discussed here. Regardless of whatever one wants to make of policy in the presence of mixed data, I think it is important for people to understand the nature of the data and analyses and the levels of scientific certainty or uncertainty involved. Then people can fit that into their own value framework.

Much of the current acrimony surrounding this issue is caused by people assuming the evidence is clearer than it is. Hopefully by recognizing the actual level of scientific certainty or lack thereof, people can come to greater peace with the idea that we live in uncertain times and that different people may reasonably make different choices about this in their lives.

 

[Palmpilot]

Why are you typing in large bold fonts?

To indicate titles of articles/papers.

 

[dmspilot]

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.

Every study has its limitations and caveats. You keep taking those limitations and caveats as the main conclusions of the paper while ignoring the actual conclusions.

 

[Everskyward]

I understand that the policy can’t be discussed here. Regardless of whatever one wants to make of policy in the presence of mixed data, I think it is important for people to understand the nature of the data and analyses and the levels of scientific certainty or uncertainty involved. Then people can fit that into their own value framework.

Much of the current acrimony surrounding this issue is caused by people assuming the evidence is clearer than it is. Hopefully by recognizing the actual level of scientific certainty or lack thereof, people can come to greater peace with the idea that we live in uncertain times and that different people may reasonably make different choices about this in their lives.

If that was true you would simply discuss the results and not bring up, 'coercive government mandates'.

 

[Jeff Oslick]

I don’t know that one can clearly attribute the cause of the recent run-up like that. Most flu seasons follow this sort of course.

The reasons for the seasonality are presently debated but may include more time inside, colder temperatures, kids in school (though presumably not as big a factor this year).

Certainly gatherings is one reasonable hypothesis, but there may be other factors that are substantial contributions as well.

When you look specifically at Southern California, you can't attribute the changes to people spending more times indoors. If anything, it would be flipped with people spending more time inside in the summer on the hottest days than in the more mild weather we've had Sept-Dec.

Occam's Razor approach to looking at the California data is that the inflection point is Halloween/Dia de Muertos (Nov. 1).

 

[PeterNSteinmetz]

Every study has its limitations and caveats. You keep taking those limitations and caveats as the main conclusions of the paper while ignoring the actual conclusions.

Ok. So which of the main key 5 points made by the authors do you think I have disagreed with?

I think I would only probably state #2 slightly differently. They say “The benefits of mask wearing seem to outweigh the harms when COVID-19 is spreading in a population.”

“Seem to” is already fairly weak but I would probably be a bit more cautious or say this with more qualification. Such as “Considering only direct health outcomes, the benefits of mask wearing seem to”. Since they did not consider secondary health effects such as people deferring other medical treatments.

I would also not write the one sentence in the conclusion as they did “Evidence that the virus can be airborne (and therefore be inhaled) and that masking policies, when effectively delivered, save lives is now strong”

This is compound and while I think the evidence for part of it has strong evidence, such as the virus can be airborne, I think the phrasing and qualifier “when effectively delivered” is not clear enough. What does “effectively delivered” mean? Does that mean when healthcare workers are wearing N95s? Certainly the evidence there is fairly strong.

But it can easily be confused by people to think it means that cloth mask wearing by the general public saves lives has strong evidence. But that is not really what they are showing in the rest of the review.

These are the sort of somewhat vague statements that often appear in discussions at the end of papers and the reason that it really is best to read the whole paper and objectively consider all of it.

Those nits aside, I think they did a good job with their five key points and overall. I think it is good that the limitations of our certainty on these questions are being more clearly discussed.

 

[PeterNSteinmetz]

When you look specifically at Southern California, you can't attribute the changes to people spending more times indoors. If anything, it would be flipped with people spending more time inside in the summer on the hottest days than in the more mild weather we've had Sept-Dec.

Occam's Razor approach to looking at the California data is that the inflection point is Halloween/Dia de Muertos (Nov. 1).

Interesting question. What does the mobility data tell us about those time points?

It is of course going to be difficult to de-confound the normal tendency for the flu to increase in the fall from any specific factor.

And it may be, as you say, that there are more indoor personal gatherings in the fall which has generally driven this. I am not expert on that literature but understand that the causes of seasonal flu variation are actively debated in the epidemiological community.

 

[Checkout_my_Six]

news just reported over 70% of all transmissions are due to home gatherings.

 

[Jeff Oslick]

What does the mobility data tell us about those time points?

Mobility data aren't going to tell you when there was a block party with 50-100 people in a small neighborhood.

 

[PeterNSteinmetz]

Mobility data aren't going to tell you when there was a block party with 50-100 people in a small neighborhood.

Crowds are definitely one of those high risk situations best avoided. Or use a good mask like an N95 if you have to be in one.

 

[Everskyward]

news just reported over 70% of all transmissions are due to home gatherings.

Anecdotally, it seems that way from the other thread where people are relating there personal experiences. I think people are much less likely to be wary of their family and friends than the person next to them on the bus, or in the supermarket.

 

[Tarheelpilot]

When it comes to leadership in this country/state/local, regardless of party, I don't disagree.

I am arguing for self-sacrifice, and I have walked-the-walk.

I’m glad you can afford to walk the walk.

 

[Checkout_my_Six]

I wouldn't ride the bus....or any other mass transit.

Anecdotally, it seems that way from the other thread where people are relating there personal experiences. I think people are much less likely to be wary of their family and friends than the person next to them on the bus, or in the supermarket.

 

[Tarheelpilot]

Edit: mask mandates also save lives (or at least have a 50/50 chance according to the OP). Which is worse? Totally valid question. It is like the classic choice of crashing the school bus to avoid a single child on the road. Which do you choose?

From mid September
https://www.medpagetoday.com/infectiousdisease/covid19/88692

Gandhi told MedPage Today that the viral inoculum, or the initial dose of virus that a patient takes in, is one likely determinant of ultimate illness severity. That's separate from patients' subsequent viral load, the level of replicating virus as measured by copies per mL.

That is the question. There are compelling arguments on all sides. It’s a matter of policy our society needs to answer. It’s also at the point we can no longer discuss it here due to ROC.

 

[Everskyward]

I wouldn't ride the bus....or any other mass transit.

I've done maybe 5 times since COVID. I used to ride the bus all the time, but the activities I went to are suspended. I'll use the bus when it's too far to walk or parking is too much of a pain. Planning to use it Monday. COVID isn't too bad around here, though.

 

[Checkout_my_Six]

bless your heart....not me. My behavior is modded since COVID.

 

[Everskyward]

bless your heart....not me. My behavior is modded since COVID.

So is mine. I formerly took it 2-3 times a week. Now not even once a month.

 

[dmspilot]

Ok. So which of the main key 5 points made by the authors do you think I have disagreed with?

You've used this paper to conclude that there is "mixed" evidence to support mask wearing.

You use the word "mixed" while the authors use the word "strongly":

"...fluid dynamics of aerosol spread and international epidemiologic data summarized in this review already strongly support the hypothesis that masks are likely to be effective..."

These are the sort of somewhat vague statements that often appear in discussions at the end of papers

They're not vague statements, they are being scientifically precise by noting the limitations involved.

it really is best to read the whole paper and objectively consider all of it.

That's right. You need to read the whole paper so you can pick up on a few words such as "seem" and use them as an excuse to flip the meaning of the entire paper and make it "seem" like it's concluding the opposite of what it actually is.

 

[Lindberg]

Flattening the curve worked — until it didn’t
The US started 2020 by “flattening the curve” — and never came up with a plan for what comes next.

https://www.vox.com/22180261/covid-19-coronavirus-social-distancing-lockdowns-flatten-the-curve

Excerpt:

The US did succeed at flattening the curve — at least at first. Businesses closed and most states issued stay-at-home orders, and later research concluded those lockdown measures helped prevent tens of millions of Covid-19 cases.

But America failed to take advantage of that window to ramp up its testing-and-tracing capabilities, and states quickly faced intense pressure to relax their policies to alleviate the economic costs of the shutdowns. Reopening began earlier than public health experts believed it should. The political will to impose new lockdowns had evaporated by the time cases spiked again.​

But America failed to take advantage of that window to ramp up its testing-and-tracing capabilities

Quoted again for emphasis. The point of flattening the curve was not to eradicate the virus because it doesn't work that way. The point was to give systems and bureaucracies tube to prepare in ways they declined to do when times were good. At least around here, they didn't do that. There's still NO contact tracing, no surveillance of active cases, and the same number of ICU beds and staff there were in January. That's all despite the fact that every single model relied on initially to justify all the "NPIs" showed that there's be spikes once restrictions were limited. But there's very few elected "leaders" with the balls to stand behind a podium and say, "People are going to die, and the consequences of effectively preventing that would be worse than letting it happen."

Frankly, they all actually know that what needs to happen is for adults to make adult decisions. You can see it in their own actions. But given how political it's all become, they won't actually say that.

 

[PeterNSteinmetz]

You've used this paper to conclude that there is "mixed" evidence to support mask wearing.

You use the word "mixed" while the authors use the word "strongly":

"...fluid dynamics of aerosol spread and international epidemiologic data summarized in this review already strongly support the hypothesis that masks are likely to be effective..."

They're not vague statements, they are being scientifically precise by noting the limitations involved.

That's right. You need to read the whole paper so you can pick up on a few words such as "seem" and use them as an excuse to flip the meaning of the entire paper and make it "seem" like it's concluding the opposite of what it actually is.

I think the authors are being precise by using "may substantially reduce" and "seem to outweigh" in their summary points. This is much weaker than what they could have said. The reason they may have chosen that wording rather than saying simply "substantially reduce" and "outweigh" is that they may recognize that the results of all the randomized trials that are available do not support this idea. And they recognize that observational studies are subject to potential large confounds, especially when looking at small effects. And in-vitro studies on particle dynamics do not account for things like fickle human behavior which occurs in actual populations.

So let's look at the actual evidence which they are dealing with, and as summarized in my initial OP:

In-vitro studies of droplet dynamics: Some fairly good reasons to think that masks interfere with transmission of respiratory droplets of the appropriate size if worn properly. Less clear about droplets when actually worn by people.

Observational studies: Some, such as Lyu & Wehby, have shown an apparent small reduction in R0, which if due to masking, could add up to a sizeable reduction in cases. But attributing causation to such small effect sizes is always tricky and one is often detecting an effect, but due to some other confound.

Randomized trials: The Danmask-19 study shows no significant effect. Interpreted as point estimate, it suggests a modest reduction of 15% however there is also a 25% chance it may have resulted in an increase in cases. Older studies of flu transmission also failed to show a significant reduction in transmission when people wore surgical masks.

It is hard to reconcile all this. It does not point to a consistent story. The randomized trials are the gold standard in clinical work for a reason -- because they avoid the problems with confounds of the observational studies and account for actual human behavior. They should be weighted more heavily in an objective evaluation than other evidence.

It is possible that given droplet dynamics that there is a source effect even though there is no noticeable effect for the wearer. Seems a stretch to me, but it is possible.

I will also note that a similar situation, some nice theory and some strongly suggestive observational work but a failure in actual randomized trials is a common outcome for proposed new treatments in medicine. Happens all the time.

Given that overall, I think "mixed" is a good description. 1/3 of the main categories of data, and the more reliable third, does not support the hypothesis that the general public wearing cloth masks slows the spread of Covid-19. The use of the word "strongly" by the authors pertained only to the other less reliable 2/3. "mixed" is also a good description of the conclusions of prior reviews looking at the effect of masks on transmission (listed on my medical interest page - they were basically 50/50 on whether a recommendation for the general public to wear cloth masks was merited), though these did not include Lyu & Wehby or Bundgaard et al. as they were not yet published.

Now if you want, we can go through and look at the specific randomized and observational studies and evaluate the strength of evidence of each, to see if "mixed" is a good description overall. That could be interesting.

Quibbling over the meaning of "may substantially reduce" versus "substantially reduce" and "seem to outweigh" versus "outweigh" and "mixed" in a brief summary versus one statement containing "clearly" in an entire paper is a perhaps interesting semantic exercise (and I understand you are an attorney so may enjoy that sort of thing) but is considerably less informative of the science than really looking at the data and analyses.

If you are truly interested in the scientific issue, let's examine those studies. You may not like my word choices in one sentence of a brief summary -- so be it. I will not be commenting further on these word choices here.

 

[PeterNSteinmetz]

That's all despite the fact that every single model relied on initially to justify all the "NPIs" showed that there's be spikes once restrictions were limited. But there's very few elected "leaders" with the balls to stand behind a podium and say, "People are going to die, avs the consequences of effectively preventing that would be worse than letting it happen."

Interestingly, one of the early studies of the likely outcome of lockdowns predicted that they might actually make things worse in the fall.