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Thread: Disease and pandemics thread (because it's science)

  1. #1381
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    The world has some good news to look forward to amid the novel coronavirus outbreak: a hole in the ozone layer is in recovery.
    https://globalnews.ca/news/6734991/o...d-flows-study/

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    At this time, researchers aren’t sure if there is a difference in infection rates between type 1 diabetes and type 2 diabetes, says Dr. Anne Peters, a leading diabetes clinician
    https://parade.com/1015544/carolyncr...s-coronavirus/

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    I have, on paper, type two diabetes and type one is a different disease entirely, although both are blood sugar related. For me, stopping a life habit of overdoing the potatoes and sugars, also stopped the potentially devastating secondary effects of type two. The link to the immune system is, I think, a simplification, just as being old is a simplification for the sake of averages. In the UK the role of diet in dealing with type two is finally being studied properly and we can hope for lifestyle changes replacing insulin substitutes. Ref: the “Newcastle diet” as a search term.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    The number of cases in Italy is starting to drop, which is very good news indeed. It seems that when you have a lockdown, even in a western nation, what happens is it takes a week to see results (either because the new cases were infected prior to the lockdown, or because of additional cases from within households), but then the new case rate levels off over the second week, and then begins a decline that takes another week to bring the new cases down substantially. Maybe give it a fourth week for good measure, that's the kind of fine tuning we will need to experiment with. So that's a three-week (maybe four) program for bringing the cases under control. Presumably the same would be true in localized regions within a country, as long as travel is limited. So I think that's our prescription for the next year or so-- roving 3-week lockdowns in emerging hotspots. That's probably economically sustainable as long as every region can locally stockpile 3 weeks worth of supplies, and any additional commerce into and out of the hotspot must be carefully monitored and controlled. Ventilators may need to be mobile and, obviously, sterilized. My guess is, an economy could be sustained like that, and the new case count could be kept pretty low overall. Deaths could be maintained at a lower level than what we already tolerate for the flu. I think this is a promising situation-- 3 weeks seems like a crucially sustainable timescale, and quite a bit less than the several-month timeframe that gets bandied about but doesn't seem to reflect the data we see coming out of lockdowns. I think the two-month kinds of figures come from a picture that the virus must be completely defeated, but I don't think that's really possible until there are vaccinations-- in the meantime, we need economically sustainable measures that keep the new case rate down to an acceptable level (say, deaths at the rate of normal flu), and it seems to me that local three-week lockdowns work for that, combined with general cleansing and social distancing measures that are fairly easy to maintain everywhere and continuously.

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    For a large country that sounds a good policy. I would add that truck and Van drivers are isolated, so deliveries can continue if people will agree to stay at home. Local door to door deliveries also possible if a town gets organised. Shopping is clearly a risk with something so infectious. But looking at the map, there are a lot of dots all over, so it will soon be too late, or it is too late to have phased lock downs.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    I don't think it's too late for phased lockdowns, indeed the entire concept of "too late" doesn't really exist, except for the original "too late to stop this from being a pandemic." But once you have a pandemic, it's all about sustainable strategies until there is vaccination. Those strategies can be classified into two general forms-- things you do all the time everywhere, and things you do locally for short times. The former must be economically sustainable, but the latter has much more flexibility. It is inevitable that our strategies for the next year must combine these, and the only locally effective strategy that people can completely understand is lockdown (though it need not necessarily mean no one is allowed outside, that's an extreme measure that hopefully will soon be unnecessary). But it does mean shutting down gatherings of all kinds, and movement outside should be limited to what is essential. I think that basically means a failing economy, so it will have to be done locally and for short periods of time. For me it's only a question of whether all this happens in a well-orchestrated way, or a slapshod and inconsistent way based on the leanings of the local authorities. Flatten the curve and then damp the oscillations-- we will need intelligent guidance to pull this off.

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    So there is a report that the CDC may recommend that everyone start wearing face masks when they leave the house.

    Medical professionals are complaining that they don't have enough face masks for their use, they have to reuse the ones they can get. And the CDC wants 300,000,000 more people to start wearing them? And we get them where?
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  8. #1388
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    Quote Originally Posted by Jim View Post
    So there is a report that the CDC may recommend that everyone start wearing face masks when they leave the house.

    Medical professionals are complaining that they don't have enough face masks for their use, they have to reuse the ones they can get. And the CDC wants 300,000,000 more people to start wearing them? And we get them where?
    The scuttlebutt is that they will recommend cloth masks. So, we’ll all look like bandits from cowboy movies.


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    Quote Originally Posted by Ken G View Post
    I actually think he was quite purposeful in meaning exactly that this is the source of serious illness. Whether he's right or not is another matter, but that's what he thinks. If I had to guess why he thinks that, I would say it is the combination of the high viral load in a droplet (as opposed to sitting on a surface for hours), along with direct delivery right to the deadly lung tissue. It seems that a key phase in "serious illness" is when the virus goes from the nose and throat into the lungs, and the longer that can be avoided, the longer the immune system has to build up its defenses. I don't know if this is a correct description, but it seems to me that when there is initial infection, a kind of race against time initiates-- a race between the time it takes the virus to find that deep and deadly lung tissue, and the time it takes the body to develop the necessary antibodies. Obviously that race will play out differently based on a host of factors, but not inhaling a large viral load directly into the lungs certainly seems to give a leg up to the immune system.
    That all sounds very reasonable. Inhaling the virus does seem to be the worse scenario. But he has to know that there's a reason why washing hands is such a ubiquitous phrase, along with the time for the virus to be potent on various surfaces.

    If correct, this state of affairs clearly has important consequences for healthcare workers. It might be that being elderly slows the immune response, thereby losing the race even if there is not direct inhalation of a large viral load, but it might also be that even a young immune system in top form still loses that race if there is direct inhalation of a large viral load. If so, then it is easy to predict that almost all deaths in people under 60 who did not have any underlying conditions (even unknown ones) will be among either healthcare workers or family members tending to sick people at home.
    Yes, older immune response systems "aren't what they used to be" no doubt. I don't heal as fast as long ago.
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by Jens View Post
    I'm not sure, but just offering some speculations: one is that type 2 diabetes is more prevalent in older people, while type 1 doesn't have that curve. So the fact that the disease is more serious among people with type 2 diabetes might be partly because type 2 diabetes is a marker for age. And secondly, people with type 2 diabetes tend to have other co-morbidities, like hypertension and cardiovascular disease.
    That's logical and I'm still green in understanding this disease.
    We know time flies, we just can't see its wings.

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    Here are some graphs that may be of interest, especially since the CFR rates are climbing.

    New Case rates US March 30.jpg
    Avg Case rate Mar 30.jpg
    Avg Death rate Mar 30.jpg
    We know time flies, we just can't see its wings.

  12. #1392
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    The CFR rates are increasing thankfully due more to the reduction in the rate of new cases (denominator), yet still ugly to look at.
    Attachment 25061
    We know time flies, we just can't see its wings.

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    RED CROSS BEGINS REGISTRATION FOR COVID-19 PLASMA DONORS
    https://6abc.com/amp/coronavirus-red...blood/6066673/

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    Quote Originally Posted by George View Post
    Here are some graphs that may be of interest, especially since the CFR rates are climbing.

    New Case rates US March 30.jpg
    Avg Case rate Mar 30.jpg
    Avg Death rate Mar 30.jpg
    just as clarification, the third graph is the new death rate, not the death rate...
    As above, so below

  15. #1395
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    Quote Originally Posted by George View Post
    Here are some graphs that may be of interest, especially since the CFR rates are climbing.

    New Case rates US March 30.jpg
    Avg Case rate Mar 30.jpg
    Avg Death rate Mar 30.jpg
    I think the y axis needs explaining. If it is a ratio Of deaths to new cases, it is not very helpful in a growing situation. Because the deaths are many days after a case is recorded.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    Quote Originally Posted by Jim View Post
    So there is a report that the CDC may recommend that everyone start wearing face masks when they leave the house.

    Medical professionals are complaining that they don't have enough face masks for their use, they have to reuse the ones they can get. And the CDC wants 300,000,000 more people to start wearing them? And we get them where?
    Face masks are going to be absolutely key in beating this virus. The successful countries enforce wearing masks when in public places. These are the countries which are winning.

    No mask is absolutely safe. You can never cut your risk to zero with a simple facemask of any rating. Yes the (US) N-rated or (EU) P-rated masks are best but we can't get them. These pass a standard of efficiency in filtering 0.3 micrometre particles. But the CV virus is passed in particles > 5 micrometres, i.e much larger than 0.3 micrometers.

    That being the case, a "PM 2.5" mask (ie it filters particles down to 2.5 micrometers) is beneficial. It might cut your virus exposure by 80%, not hugely different to one of the N or P-rated masks (bearing in mind that leakage around the edges is the weak point of all these masks).

    So there is still a risk to the individual. But at a population level, there is a world of difference between Ro =1.01 and Ro = 0.99. Even quite small benefits from widespread mask wearing (in combination with social distancing) could be enough to drive Ro below 1.0.

    Like you say though, the supply side would need really ramping up.

  17. #1397
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    Quote Originally Posted by Jim View Post
    So there is a report that the CDC may recommend that everyone start wearing face masks when they leave the house.

    Medical professionals are complaining that they don't have enough face masks for their use, they have to reuse the ones they can get. And the CDC wants 300,000,000 more people to start wearing them? And we get them where?
    This article seems to have a good discussion of the issues. Again, some mention of politicians, but is a technical discussion that doesn’t appear to be taking a political editorial position. It points out some of the arguments pro and con, and says there isn’t a good consensus. There are also cultural biases, with various Eastern cultures using them regularly anyway, but not so much in Western cultures:

    https://www.politico.com/news/2020/0...tration-156327

    In general, what I am hearing is that there is now more solid evidence of significant numbers of people that are asymptotic but spreading the virus. The more common idea is that masks would tend to make it harder for an infected person to spread the virus. It isn’t so much the idea of protecting the person with the mask, although some are arguing that too. Simple masks are claimed to still help if someone coughs, etc.

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    Quote Originally Posted by kzb View Post
    Face masks are going to be absolutely key in beating this virus. The successful countries enforce wearing masks when in public places. These are the countries which are winning.

    No mask is absolutely safe. You can never cut your risk to zero with a simple facemask of any rating. Yes the (US) N-rated or (EU) P-rated masks are best but we can't get them. These pass a standard of efficiency in filtering 0.3 micrometre particles. But the CV virus is passed in particles > 5 micrometres, i.e much larger than 0.3 micrometers.

    That being the case, a "PM 2.5" mask (ie it filters particles down to 2.5 micrometers) is beneficial. It might cut your virus exposure by 80%, not hugely different to one of the N or P-rated masks (bearing in mind that leakage around the edges is the weak point of all these masks).

    So there is still a risk to the individual. But at a population level, there is a world of difference between Ro =1.01 and Ro = 0.99. Even quite small benefits from widespread mask wearing (in combination with social distancing) could be enough to drive Ro below 1.0.

    Like you say though, the supply side would need really ramping up.
    I think there is more to it than that. Countries which are on the winning side also spray disinfectant in full Hazmat gear into empty streets. OTOH, epicenters such as New York and Quebec, suggest daily walks in the streets while discouraging wearing of masks. Both of two contradicting approved can not be right.

  19. #1399
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    Quote Originally Posted by a1call View Post
    I think there is more to it than that. Countries which are on the winning side also spray disinfectant in full Hazmat gear into empty streets. OTOH, epicenters such as New York and Quebec, suggest daily walks in the streets while discouraging wearing of masks. Both of two contradicting approved can not be right.
    You know those machines blowing out the white clouds, what are they spraying? What is the white smoke?

    Personally not convinced this is much use, particularly in the open. It might be beneficial in indoor public places. Outside, solar UV should kill off CV quite quickly anyhow.

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    Quote Originally Posted by kzb View Post
    Face masks are going to be absolutely key in beating this virus.
    For health-care workers and those in close contact with infected patients who are coughing, sure.
    Otherwise, it fails the "Does it make sense?" test. Those who are being vocal about this in the USA at present are citing a Cochrane Review paper which doesn't actually seem to say what they seem to think it says. The studies supporting mask-wearing involve doing it in health-care settings and during close contacts with infected patients, as well as public mask wearing. It's a pretty heterogenous dataset.
    The countries which have so far managed to suppress COVID-19 spread certainly have public mask wearing as part of their culture, but are in situations, and are applying interventions, that are also effective at suppressing COVID-19 spread. We have to be cautious not to fall into a cum hoc ergo propter hoc fallacy. Correlation does not imply causation.

    Grant Hutchison

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    Quote Originally Posted by George View Post
    That all sounds very reasonable. Inhaling the virus does seem to be the worse scenario. But he has to know that there's a reason why washing hands is such a ubiquitous phrase, along with the time for the virus to be potent on various surfaces.
    I might speculate that the concern there is if people pick up the virus from a surface, they will become someone who could kill someone else by coughing into the air. We certainly all benefit by not having lots of sick people around, but what is best for that individual might be a different matter. CDC guidelines have to think about what's best for the whole society. There's also the problem that young people can require a hospital visit even if their prognosis is good, and that taxes hospital resources (and endangers healthcare personnel). So I get why we want people to avoid getting sick, but I feel like there's a dearth of information being shared about the severity of illness correlated with the means of getting sick.

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    One thing about mask wearing is that if simple cloth masks can help reduce R0 for a society, it's certainly worth it, because it's of almost no cost. I don't think a false sense of security is a big issue, because at least it makes a statement that serves as a reminder of the need to social distance. In other words, I don't think people will react like "hey, they're all wearing masks, so it's OK if I pack into a closed room with them", I think they react like "wow, everyone is wearing a mask, they might be sick, I better keep away." That could be a benefit of masks with zero physiological basis, yet still help R0. For sustainable strategies, we need to start thinking about the concept of "societal cost per 0.1 reduction in R0."

  23. #1403
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    From Matador Travel Security
    Latest developments: April 1, 2020

    Strict containment measures might have already saved up to 59,000 lives across 11 European countries battling the spread of the new coronavirus, experts in the UK say. Basing their modelling on the numbers of recorded deaths from COVID-19, researchers from Imperial College London said most countries it looked at had likely dramatically reduced the rate at which the virus spreads. Using the experiences of countries with the most advanced epidemics like Italy and Spain, the study compared actual fatality rates with an estimate of what would have happened with no measures such as school closures, event cancellations and lockdowns. More than a third of the world's population is now under lockdown as an increasing number of countries implement sweeping measures to fight the coronavirus pandemic.

    China's National Health Commission has yet to release its daily update on coronavirus cases, with asymptomatic cases expected to be added to the tally.

    Japan Post will stop delivering letters and parcels to more than 150 countries from Thursday as flights are cancelled because of the coronavirus. Mail will continue to the US, France, Australia and Hong Kong among a handful of places. Other national postal services in Asia, including Hong Kong and Malaysia, have also reduced services because of the lack of flights.

    In Japan's capital, Tokyo, new infections rose to a daily record of 78 on March 31, for a total of more than 500. Schools have been closed since March 2 and expectations are growing the shutdown will be extended. A March 30 report indicated that Japan is considering banning the entry of visitors who have recently been in the U.S., China, South Korea, and most of Europe. The measure would reportedly apply to foreign nationals who have been to any of those areas within 14 days of arriving in Japan. Moreover, Japan’s Foreign Ministry is also likely to raise its travel advisory for the U.S., China, South Korea, and most of Europe (including the UK) to Level 3, warning Japanese citizens to “avoid all travel” to those countries. Japan has reported some 2,178 cases and 57 deaths.

    South Korea has confirmed 101 new cases of coronavirus, most of them in and around the capital Seoul. Many are linked to people arriving from overseas, and the country has today begun to enforce mandatory quarantine on all those coming from abroad, including South Korean students. Those who break the rules risk a fine of as much as US$8,200 or jail, while foreigners can be expelled.

    Taiwan has started asking all citizens to wear masks when they take public transportation today. Those who are feverish will not be allowed to go to trains stations or airports.

    Malaysia is tightening its lockdown, as the so-called Movement Control Order that was originally to have come to an end on March 31 enters its "second phase". The Home Ministry says that for the next two weeks, public transport will operate only during limited hours in the morning and evening, while private vehicles (including e-hailing services) will be banned from the roads between 10pm (14:00 GMT) and 6am (22:00 GMT).

    29 doctors and nurses at a hospital in northern Mexico have reportedly been diagnosed with coronavirus. The outbreak at the government-owned IMSS General Hospital in Monclova in the northern border state of Coahuila is thought to have started when a doctor picked up the virus from a patient at his private practice.

    The death toll in the United States from COVID-19 has surpassed the official tally in China, with 4,081 fatalities recorded, according to data collected by the Johns Hopkins University. The US now has the third highest death toll after Italy and Spain, and the highest number of cases in the world with 189,633. Further restrictions on movement are being considered.

    For more information on the above and latest updates for your areas of interest please visit the International SOS website.

    The global number of reported infections now stands at 862,234 with 42,404 fatalities. 178,836 people are reported to have recovered.

    Updated figures can be found on Johns Hopkins University's coronavirus tracking map.​​​​​​
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  24. #1404
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    Quote Originally Posted by grant hutchison View Post
    For health-care workers and those in close contact with infected patients who are coughing, sure.
    Otherwise, it fails the "Does it make sense?" test. Those who are being vocal about this in the USA at present are citing a Cochrane Review paper which doesn't actually seem to say what they seem to think it says. The studies supporting mask-wearing involve doing it in health-care settings and during close contacts with infected patients, as well as public mask wearing. It's a pretty heterogenous dataset.
    The countries which have so far managed to suppress COVID-19 spread certainly have public mask wearing as part of their culture, but are in situations, and are applying interventions, that are also effective at suppressing COVID-19 spread. We have to be cautious not to fall into a cum hoc ergo propter hoc fallacy. Correlation does not imply causation.

    Grant Hutchison
    Amen to that, any filter also accumulates filtrate, so the whole protocol of maskwearing has to be thought through. Yes it will limit the trillions of particles from an infected cough, but it also stores and accumulates ambient particles which remain infectious for hours or days. Plus the tendency to breathe harder through a mask and to touch it regularly, especially if unaccustomed. Spacing discipline makes sense and may make the mask redundant. Finally, masks tend to collect water too, from breathing, does that allow longer time for the virus before desiccation finishes it off?
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    Quote Originally Posted by profloater View Post
    I think the y axis needs explaining. If it is a ratio Of deaths to new cases, it is not very helpful in a growing situation. Because the deaths are many days after a case is recorded.
    Sure. The y-axis is the daily rate (% increase over the prior day) for each of the three categories. For instance, the US no. of cases yesterday totaled 161,807, up 20,921 in new cases from the prior day's total of 140,886. This is an increase rate for yesterday of 14.8% (20,921/140,886). So as bad as those numbers look, the actual daily rate is coming down, which should be worth noting. The semi-vertical graphs at many sites like Johns Hopkins are don't graphically tell the full story, and I suspect this approach does help. Does it?

    The CFR values are about double if you use a 4-day time lag, of course higher for each increase in lag days. From earlier graphs where I used 2,4,6,8 and 10 day delay periods, there was no noticeable bump in the profile between those higher CFR values, respectively. IOW, it seemed to me at least that there must be a somewhat even distribution in the no. of days until death, though I suspect I might be wrong in that simple assumption.
    Last edited by George; 2020-Apr-01 at 03:13 PM.
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    Quote Originally Posted by grant hutchison View Post
    For health-care workers and those in close contact with infected patients who are coughing, sure.
    Otherwise, it fails the "Does it make sense?" test. Those who are being vocal about this in the USA at present are citing a Cochrane Review paper which doesn't actually seem to say what they seem to think it says. The studies supporting mask-wearing involve doing it in health-care settings and during close contacts with infected patients, as well as public mask wearing. It's a pretty heterogenous dataset.
    The countries which have so far managed to suppress COVID-19 spread certainly have public mask wearing as part of their culture, but are in situations, and are applying interventions, that are also effective at suppressing COVID-19 spread. We have to be cautious not to fall into a cum hoc ergo propter hoc fallacy. Correlation does not imply causation.

    Grant Hutchison

    Well I look at Tables 1.3 and 1.4, and see the interventions of "wearing a mask" and "wearing a N95 mask". Both tables show very significant benefits in wearing the mask.

    In a store or other public place, I might not be in a clinical setting. But I am still potentially in range of infected individuals who might cough, sneeze, talk loudly, or do whatever it takes to give off infective particles. I was in a store on Saturday and the kid 4 metres in front of me started coughing. I immediately exited the store in the opposite direction, but others did not.

    I don't see what the functional difference is between a clinical setting and a store. In both places persons are at risk of encountering infective particles. Also, what you are saying means respiratory protection is a waste of effort in the workplace. So although correlation does not necessarily mean causation, sometimes you have to say it stands to reason, because there is a plausible mechanism for causation.

  27. #1407
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    The mask discussion is essentially moot until there is a supply available for the general public. Meanwhile, for better or worse , people are making their own.

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    Quote Originally Posted by Ken G View Post
    One thing about mask wearing is that if simple cloth masks can help reduce R0 for a society, it's certainly worth it, because it's of almost no cost. I don't think a false sense of security is a big issue, because at least it makes a statement that serves as a reminder of the need to social distance. In other words, I don't think people will react like "hey, they're all wearing masks, so it's OK if I pack into a closed room with them", I think they react like "wow, everyone is wearing a mask, they might be sick, I better keep away." That could be a benefit of masks with zero physiological basis, yet still help R0. For sustainable strategies, we need to start thinking about the concept of "societal cost per 0.1 reduction in R0."
    There does seem to be more encouragement to wear some sort of covering, especially since there does seem to be a large number of cases that are asymptomatic. The covering will minimize that person's droplet propagation and there was one account (Dr.?) that mentioned that coughs (perhaps sneeze) could have a range over 20', but that would be a very discourteous cough.

    Others mention the negatives to using face covers -- I'll reserve "mask" to distinguish it as the professional N95-type of covering -- but the pros seems to easily outweigh the cons. Nevertheless, I would appreciate those knowledgeable to suggest what cover wearers should be aware of and any tips about cleaning, etc. I'm considering placing a somewhat large order for cowboy bandanas (this is Texas) to offer them to remaining co-workers and perhaps to those we serve in public works. The old phrase "Say it; don't spray it!" comes to mind. [Would that be with a comma or the semi-colon?]
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by profloater View Post
    Amen to that, any filter also accumulates filtrate, so the whole protocol of maskwearing has to be thought through. Yes it will limit the trillions of particles from an infected cough, but it also stores and accumulates ambient particles which remain infectious for hours or days. Plus the tendency to breathe harder through a mask and to touch it regularly, especially if unaccustomed. Spacing discipline makes sense and may make the mask redundant. Finally, masks tend to collect water too, from breathing, does that allow longer time for the virus before desiccation finishes it off?
    Yes it is definitely wise to treat the mask or filter as a disposable item. Apparently, washing, or even dipping in isopropanol, significantly worsens mask filtering efficiency.

    Wash hands immediately after handling a used mask or filter also.

    Spacing discipline should make the mask redundant that is true, but in the real world, in a real store with kids and people who don't bother, I think masks should cut Ro.

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    Quote Originally Posted by Ken G View Post
    One thing about mask wearing is that if simple cloth masks can help reduce R0 for a society, it's certainly worth it, because it's of almost no cost. I don't think a false sense of security is a big issue, because at least it makes a statement that serves as a reminder of the need to social distance. In other words, I don't think people will react like "hey, they're all wearing masks, so it's OK if I pack into a closed room with them", I think they react like "wow, everyone is wearing a mask, they might be sick, I better keep away." That could be a benefit of masks with zero physiological basis, yet still help R0. For sustainable strategies, we need to start thinking about the concept of "societal cost per 0.1 reduction in R0."
    There are risks associated with mask wearing, and you can see them in action on the television every night.
    Yesterday, I watched an official from a hospital in Italy, wearing gloves and a mask, open the hospital door with his gloved hand, then hook a finger over the top of his mask next to his nose to pull it down in order to speak to a journalist, passing his hooked finger over his lips as he did so, and contaminating the inside the mask which he would later pull up over his face again. Gloves useless, mask worse than useless.
    People just don't use masks properly without training--they touch their faces, they touch the insides of the mask, they reuse masks that are damp and have been allowed to rest on random surfaces. By doing so they undoubtedly increase their risk above the baseline achieved by social distancing.
    The evidence for risk reduction in social settings with social distance is slight and equivocal (see my link above), and on theoretical grounds it would seem that good mask use would make a very slight reduction in R0 compared to simple social distancing and good hand hygiene. The worry is that that might be offset by the risks of bad mask use, and mask reuse.
    So the next problem is that healthcare resources are everywhere and always scarce (a basic tenet of public health planning), so we should put those scarce resources where they produce most effect on R0 and on mortality--and in the case of masks that has to be healthcare workers first, who are exposed to the highest risk of contracting the disease, and whose absence from the workplace will most impact the care of others.
    In an ideal world, with an infinitely renewable supply of useful masks and a trained public, then by all means we should distribute many masks to everyone because any tiny reduction in R0 is good. In the less-than-ideal world the WHO is dealing with, their pragmatic advice makes sense.

    Grant Hutchison

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