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

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PeterNSteinmetz said:
Interestingly, one of the early studies of the likely outcome of lockdowns predicted that they might actually make things worse in the fall.
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I'm not a scientist. I'm not an epidemiologist. But I said at the outset, when the shutdowns started, that one the curve was flat, we needed to reopen enough to let infections happen consistently at a manageable rate. Because otherwise....


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But we'd need Winston Churchill caliber leaders to sell that.
 
Everskyward said:
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.
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I have to ride a transcontinental flight twice a month for work. I can’t afford not to ride the airplane. My flight back to California earlier this week only had two empty seats. Sometimes there just isn’t the option to avoid a crowd.
 
Tarheelpilot said:
I have to ride a transcontinental flight twice a month for work. I can’t afford not to ride the airplane. My flight back to California earlier this week only had two empty seats. Sometimes there just isn’t the option to avoid a crowd.
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Wear an N95 or P100. If you can’t get the disposables, get a 3M 6200 and it’s N95s, which are more available. You can then 3D print the adaptors to add cloth over the outflow valve.
 
PeterNSteinmetz said:
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.
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Peter, I appreciate your analysis in this thread. Sometimes, it's hard to discuss these tough issues with people when they are 1) assimilating facts to their belief, rather than formulating beliefs based on the evidence, and 2) are emotionally attached to their pre-conceived ideas. But I think you have done an admirable job throughout this thread of discussing the evidence and the degree to which they support various conclusions.
 
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Palmpilot said:
This article attempts to explain why California is having a rough time:

https://www.theguardian.com/us-news/2020/dec/28/how-california-went-from-leader-covid-fight-despair

This article deals with compliance issues at Lake Tahoe, which is partly in California:

https://www.theguardian.com/world/2...les-winter-vacationers-coronavirus-california
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Does any of that explain why California is doing significantly worse than Florida is without restrictions?

And this stuff is just maddening incompetence:
Newsom’s recent suggestion of a two-day program to train up additional ICU nurses felt like “a slap in the face”, Vasquez added. “It made me think like, ‘Well gosh, Governor Newsom, I hope your family member doesn’t end up in the ICU, being cared for by a nurse with two days of training.’”
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Long after "two weeks to flatten the curve" and "eight months to eradicate the virus," why are they just now considering cross training nurses? It's like they didn't use the time we bought them with our sacrifices to do anything.
 
Lindberg said:
Does any of that explain why California is doing significantly worse than Florida is without restrictions?.
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No, those articles only deal with the California half of his question. I posted them because they showed up in my phone's news feed and seemed at least partially relevant.

I haven't been following Florida news much. Do they really have zero restrictions?
 
Lindberg said:
Does any of that explain why California is doing significantly worse than Florida is without restrictions?
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There is no way to discuss Florida vs. California performance on COVID without getting into potentially political discussions of data comparability.
 
Jeff Oslick said:
That is like trying to determine a crosswind component when you only know what runway you're landing on, but have little or no idea of the windspeed or direction.
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Just do open vs. closed for California then. Or any other comparison that meets your standards. But it's January 2021. Citing data from May 2020 suggesting restrictions works ain't it. And blaming noncompliance ain't it either because the optimal public policy has to take that into account. The longer and more restrictive policies are, the less people will comply.
 
There was no significant change in California rules from the late summer/early fall until just before Thanksgiving. I am not at all arguing that the current take-out-only rules for California are significantly effective. I don't think they are.

The problem is private gatherings and large non-compliant public ones where there is no enforcement, or scientifically unwarranted exceptions have been given.

If you look at the most recent Florida data, they aren't doing that much better than California now on case count per capita or percent positive testing. Their problems may just be a few weeks behind California's (i.e., started on Thanksgiving vs. Halloween).
 
Jeff Oslick said:
There was no significant change in California rules from the late summer/early fall until just before Thanksgiving. I am not at all arguing that the current take-out-only rules for California are significantly effective. I don't think they are.

The problem is private gatherings and large non-compliant public ones where there is no enforcement, or scientifically unwarranted exceptions have been given.

If you look at the most recent Florida data, they aren't doing that much better than California now on case count per capita or percent positive testing. Their problems may just be a few weeks behind California's (i.e., started on Thanksgiving vs. Halloween).
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Where this is all headed is people are tired of the restrictions and their risk assessment conclusions are changing.
 
Jeff Oslick said:
There is no way to discuss Florida vs. California performance on COVID without getting into potentially political discussions of data comparability.
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...such as whether the states have similar reporting standards.
 
Tarheelpilot said:
Where this is all headed is people are tired of the restrictions and their risk assessment conclusions are changing.
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I don't think people's risk assessment is changing. People who were risk averse before are still that way. The thing that's changing is people's tolerance for rules which they don't think are accomplishing much, and hurting other areas. People were more willing to go along when they thought it would only be a short time. Then there was the emphasis on protecting the vulnerable even if you're not concerned about yourself. Pretty soon the vulnerable are going to be protected by vaccine, so we'll see what happens. As far as California is concerned, it's in no way as homogeneous as people who don't live here think. California is as diverse in opinion and behavior as the country as a whole. COVID has not affected it to the same extent in all areas. I live in San Francisco, which you might think would have a big problem, but it is doing better than many cities in the country, and much better than the Los Angeles area. I've been waiting for the other shoe to drop, but it hasn't, yet.
 
Everskyward said:
I don't think people's risk assessment is changing. People who were risk averse before are still that way. The thing that's changing is people's tolerance for rules which they don't think are accomplishing much, and hurting other areas. People were more willing to go along when they thought it would only be a short time. Then there was the emphasis on protecting the vulnerable even if you're not concerned about yourself. Pretty soon the vulnerable are going to be protected by vaccine, so we'll see what happens. As far as California is concerned, it's in no way as homogeneous as people who don't live here think. California is as diverse in opinion and behavior as the country as a whole. COVID has not affected it to the same extent in all areas. I live in San Francisco, which you might think would have a big problem, but it is doing better than many cities in the country, and much better than the Los Angeles area. I've been waiting for the other shoe to drop, but it hasn't, yet.
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I work in imperial valley. California is special.
 
Everskyward said:
...I live in San Francisco, which you might think would have a big problem, but it is doing better than many cities in the country, and much better than the Los Angeles area. I've been waiting for the other shoe to drop, but it hasn't, yet.
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Does San Francisco have a larger-than-average Asian population? I noticed that people in the Asian market near me were early-adopters of wearing masks, and I have the impression that Asians are more conscientious about it than the rest of us.
 
Palmpilot said:
Does San Francisco have a larger-than-average Asian population? I noticed that people in the Asian market near me were early-adopters of wearing masks, and I have the impression that Asians are more conscientious about it than the rest of us.
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I would say yes, more Asians, especially in my neighborhood. When I first moved here, I noticed that some Asians wore masks. I thought they were a little germ-phobic until someone told me that many do that out of courtesy when they have symptoms of a cold, etc. However, I don't think they did this in great enough numbers to affect the spread. San Francisco is pretty compliant with masks, though. It's some of the other restrictions that annoy people more.

I also noticed that even before the first shutdown in March, there were far fewer people riding the busses. The big tech companies told their employees to work from home before the city imposed rules. Also, Chinatown was pretty deserted. I (used to) ride a bus through Chinatown to get to a volunteer job. In the past, people would try to crowd on, until the door wouldn't close. When the pandemic became news in China, that stopped. People still had to stand, but it wasn't nearly as crowded. This was in January/February, before restrictions.
 
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Lindberg said:
And this stuff is just maddening incompetence:
Long after "two weeks to flatten the curve" and "eight months to eradicate the virus," why are they just now considering cross training nurses? It's like they didn't use the time we bought them with our sacrifices to do anything.
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As a physician, I’m personally holding off criticism of the “2-day training” until I learn more specifics. It seems to be presented in the cited quote as if one can take any nurse and, in 2 days, make them an ICU nurse. I don’t think that’s what was proposed.

There are multiple levels of care different types of nurses provide, many overlapping and many “almost” the same as some others. For example, while we are all familiar to some degree with ICUs and their nurses, there are also “step-down” units with patients of lower complexity but still on ventilators, medical drips, etc. Training one of these nurses, who are often already well on their way to becoming an ICU nurse, to handle SELECT patients and SELECT treatments in 2 days is not unreasonable, with proper oversight after they’re in the ICU.

And I doubt any nurse would be expected to perform past their qualifications: even more than for physicians, their state licensing boards are very strict - sometimes harsh - about scope-of-practice. Those licensing boards supersede hospital policies. Incidentally, I used to survey hospitals for their compliance with medical refs and standards. While we expected them to have an emergency privileging/scope-of-practice process, that didn’t mean they could implement one without regard for patient safety.

A quick check to see what this was all about led to this article - in the Nursing literature: https://aacnjournals.org/ajcconline...Rapid-Critical-Care-Training-of-Nurses-in-the

That’s 10 days but I’m not sure what the 2 days refers to. The article just feels like click-bait. And I know “senior” nurses have responded in the press about the general idea but I’d want to learn more before judging the idea.
 
Llewtrah381 said:
As a physician, I’m personally holding off criticism of the “2-day training” until I learn more specifics. It seems to be presented in the cited quote as if one can take any nurse and, in 2 days, make them an ICU nurse. I don’t think that’s what was proposed.

There are multiple levels of care different types of nurses provide, many overlapping and many “almost” the same as some others. For example, while we are all familiar to some degree with ICUs and their nurses, there are also “step-down” units with patients of lower complexity but still on ventilators, medical drips, etc. Training one of these nurses, who are often already well on their way to becoming an ICU nurse, to handle SELECT patients and SELECT treatments in 2 days is not unreasonable, with proper oversight after they’re in the ICU.

And I doubt any nurse would be expected to perform past their qualifications: even more than for physicians, their state licensing boards are very strict - sometimes harsh - about scope-of-practice. Those licensing boards supersede hospital policies. Incidentally, I used to survey hospitals for their compliance with medical refs and standards. While we expected them to have an emergency privileging/scope-of-practice process, that didn’t mean they could implement one without regard for patient safety.

A quick check to see what this was all about led to this article - in the Nursing literature: https://aacnjournals.org/ajcconline...Rapid-Critical-Care-Training-of-Nurses-in-the

That’s 10 days but I’m not sure what the 2 days refers to. The article just feels like click-bait. And I know “senior” nurses have responded in the press about the general idea but I’d want to learn more before judging the idea.
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My point was that they haven't had only 2 days or 10 days; they've had since at least March. Shedding crocodile tears about 2 days ignores reality.
 
Lindberg said:
My point was that they haven't had only 2 days or 10 days; they've had since at least March. Shedding crocodile tears about 2 days ignores reality.
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Could it also be the case that it sets up a cascade of training events just like at the airlines? Move one important nurse/PA/RN and now you have to retrain this person, and this person, and this person, etc.
We need all the regular nurses all the time, so you can’t just go around moving them all to new places. I thought there was a constant nursing shortage in the years before 2020.
 
Matthew Rogers said:
Move one important nurse/PA/RN and now you have to retrain this person, and this person, and this person, etc.
We need all the regular nurses all the time, so you can’t just go around moving them all to new places. I thought there was a constant nursing shortage in the years before 2020.
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That’s true but don’t forget our healthcare system is largely built on a for-profit model, even in not-for-profit hospitals. Resourcing, including staffing, is geared towards profitability, which means it’s geared towards a LOT of elective cases. Ironically, despite the crush of Covid, there were lots of healthcare people sitting idle, especially early on, because elective procedures were stopped. Temporarily shifting away from elective cases frees up a lot of resources - unfortunately not always in the right mix.
 
Matthew Rogers said:
Could it also be the case that it sets up a cascade of training events just like at the airlines? Move one important nurse/PA/RN and now you have to retrain this person, and this person, and this person, etc.
We need all the regular nurses all the time, so you can’t just go around moving them all to new places. I thought there was a constant nursing shortage in the years before 2020.
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We don't need all the regular nurses all the time during a crisis. When they closed hospitals to most non-emergent cases early on, a lot of people were laid off or furloughed.
 
I was in FL a week ago, I liked it. The individual and/or the business can mostly decide. With a few protocols in place, I don’t see how a restaurant is any higher likelihood than the grocery store. Yes, we need the store more, but more & more restaurants are closing down. They need customers sitting in, selling a few drinks.

Then we could get into how most wear, handle & change a mask. The average user doesn’t employ surgeon level methods of mask use. Are there some who allow more risk, thinking the mask is their armor?

I have my snowmobiles ready for a U.P. of MI venture. Right now most any trail stop is closed to indoor anything. I’ll wait a bit. Any talk about the Rona runs the spectrum of opinions. It’s interesting how some want the vaccine yesterday & a big % says, ‘not for me’.
 
sourdough44 said:
I don’t see how a restaurant is any higher likelihood than the grocery store.
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??? Ummm.....

In the grocery store, the average visit is 30 minutes or less (my average for a family of 3), everyone is wearing a mask and not taking it off, the volume of the building is very large per person, and you are not close to any single person for more than 5-10 minutes (in line).

In a restaurant, most people are there for an hour or more, very few people wear their mask (even in between eating and drinking), the volume of the building is much smaller than a grocery store, and you are sitting close to other tables for all that time.

Still don’t see any differences for transmitting an airborne virus?
 
If you are near one person for 20 minutes in one case and near 20 people for 1 minute...
 
Matthew Rogers said:
??? Ummm.....

In the grocery store, the average visit is 30 minutes or less (my average for a family of 3), everyone is wearing a mask and not taking it off, the volume of the building is very large per person, and you are not close to any single person for more than 5-10 minutes (in line).

In a restaurant, most people are there for an hour or more, very few people wear their mask (even in between eating and drinking), the volume of the building is much smaller than a grocery store, and you are sitting close to other tables for all that time.

Still don’t see any differences for transmitting an airborne virus?
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In the grocery store, everyone is handling everything before choosing an item - touching, moving, picking up and putting back ... that same tomato gets handled who knows how many times.
In the restaurant, my table settings were placed once and only I handle them until I'm done.
We believe my wife got it from the grocery store. She was quite strict with mask wearing. I got it from her.
 
Bob Noel said:
If you are near one person for 20 minutes in one case and near 20 people for 1 minute...
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Being near an infected person for one minute has proven to be relatively low risk because of the dose-infection relationship. This makes walking down a path, or passing an infected person on the sidewalk, not a common source of infection. But it also makes home gatherings where you are near a few people for hours at a time the source of more than 70% of all NY infections.

Next most common infections is hospital or healthcare sources, but again that is a long term exposure and also with people who all have high contact with COVID, however there is good mask and health protocols which home gatherings don’t follow.

Just behind that is restaurants, the next longest term exposure. See a pattern?

You can’t get rid of health care. Nobody seems to able to convince some people from inviting over guests to their homes, so that leaves restaurants as one way to help slow the spread.
 
gkainz said:
In the grocery store, everyone is handling everything before choosing an item - touching, moving, picking up and putting back ... that same tomato gets handled who knows how many times.
In the restaurant, my table settings were placed once and only I handle them until I'm done.
We believe my wife got it from the grocery store. She was quite strict with mask wearing. I got it from her.
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It has been disproven that touching contact and foamites (large droplets or contaminated surfaces) are a significant source of infection.
 
Matthew Rogers said:
It has been disproven that touching contact and foamites (large droplets or contaminated surfaces) are a significant source of infection.
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It has never been put forth as significant, only as a relatively easy to mitigate possible transmission route.
 
Matthew Rogers said:
It has been disproven that touching contact and foamites (large droplets or contaminated surfaces) are a significant source of infection.
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not significant, but apparently still possible, as the grocery store was pretty much her only trips to the outside world for 2 weeks leading up to her becoming symptomatic and subsequent positive test (she went to the docs firmly convinced she had strep throat).

I did not take any additional precautions within my house to separate from her (but did maintain strict quarantine from the outside world). She waited until the last hour of the last day to pass it along to me ... actually thought I dodged the bullet on it! The O Neg blood type resistance rumor held out as long as it could.
 
gkainz said:
not significant, but apparently still possible, as the grocery store was pretty much her only trips to the outside world for 2 weeks leading up to her becoming symptomatic and subsequent positive test (she went to the docs firmly convinced she had strep throat).

I did not take any additional precautions within my house to separate from her (but did maintain strict quarantine from the outside world). She waited until the last hour of the last day to pass it along to me ... actually thought I dodged the bullet on it! The O Neg blood type resistance rumor held out as long as it could.
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I just make sure that I wash my hands for twenty seconds when I get home, and avoid touching my face before then. However, there's no such thing as a virus-avoidance strategy that is 100% effective. (That doesn't mean they're not worth doing.)
 
Matthew Rogers said:
??? Ummm.....

In the grocery store, the average visit is 30 minutes or less (my average for a family of 3), everyone is wearing a mask and not taking it off, the volume of the building is very large per person, and you are not close to any single person for more than 5-10 minutes (in line).

In a restaurant, most people are there for an hour or more, very few people wear their mask (even in between eating and drinking), the volume of the building is much smaller than a grocery store, and you are sitting close to other tables for all that time.

Still don’t see any differences for transmitting an airborne virus?
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Keeping the restaurants from going out of business is just as important as keeping people alive. Many seem to forget that part of society’s needs... you know. A productive economy.
 
Tarheelpilot said:
Keeping the restaurants from going out of business is just as important as keeping people alive. Many seem to forget that part of society’s needs... you know. A productive economy.
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I can't believe that you are saying that. You literally just said that a business is just as important as a person's life. Somehow you can't live for a year without going out to dinner, so just let more people die. It is amazing how some people can't seem to make sacrifices for others.

But

I assume you are happy to trade your life for my business. Thanks, but I am not sure how we are going to execute this transaction. Have your people call my people.
 
X3 Skier said:
IBTL
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I know, but people just can’t go around saying that a restaurant is more important than my child’s grandmother because they wanted to grab a burger and beer inside a restaurant instead of ordering takeout.
 
Actually, at least here in the US, they can.

Just as others are free to disagree and provide their reasoning.
 
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