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

  1. #1501
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    I would think even a less effective mask would tend to retard spread from a mask wearer to others as the virus is largely going to be spread by droplets spread by coughing and/or sneezing; the mask will stop some proportion of those. Stopping even 10 or 15% of the droplets could have result in a significant drop in transmission. Perfect? No. Better than nothing? Probably.
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  2. #1502
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    Quote Originally Posted by schlaugh View Post
    Not sure if this was cited elsewhere in this thread, but here is a link to "a cluster randomised trial of cloth masks compared with medical masks in healthcare workers" conducted in Hanoi in 2015. Note that this is in a clinical setting and not in a wider community so it's a bit of apples to oranges.
    I'd have to question the ethics of such a study. Can you imagine asking a hospital to not use good masks, but use lousy ones instead, just to show the rather obvious point that some masks are better than others?

  3. #1503
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    Quote Originally Posted by grant hutchison View Post
    There are not enough masks in the world to deliver any widespread programme of citizens wearing masks, and it appears that there won't be before the end of the year (3M figure they can make a billion N95s by the end of the year, which is a drop in the ocean if you imagine everyone wearing one every day) The ghastly international "mask wars" that are currently depriving health care professionals of masks reflects that reality.
    So you're talking about N95 masks, or maybe down to K80. Yes, I have always agreed that N95 masks should be reserved for healthcare professionals, as is being done in the US now. The issue is homemade cloth masks, there is no kind of war going on there (except that rubber bands of all kinds are now hard to get, but hopefully it's pretty easy to make rubber bands, and one can always use other means). So are you saying that South Korea is rationing N95 masks (or perhaps down to K80)? Rated masks are more about being in a virulent environment for long periods of time and being protected, I'm thinking more about a single person sneezing in a supermarket, and what's the difference if they are wearing a cloth mask, or not wearing one. And how many others who are wearing masks get it, even though the exposure was shortlived. In a medical setting, you need N95 or you are pretty much going to get sick, and maybe even then. That's not like the difference between R0 of 1.2 and 1.1 in a scale-invariant public setting.
    Last edited by Ken G; 2020-Apr-04 at 05:09 PM.

  4. #1504
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    Quote Originally Posted by Ken G View Post
    I'd have to question the ethics of such a study. Can you imagine asking a hospital to not use good masks, but use lousy ones instead, just to show the rather obvious point that some masks are better than others?
    I had the same thought but it may have been a case of "we may have to use what's available so let's test it and see." Or the authors needed evidence to make a case of buying better masks. So what would seem to be obvious may not be once details are known; that's why you test. And as Grant pointed out, this wasn't the first study of mask effectiveness; previous studies probably had similar ethics concerns.

  5. #1505
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    So if i understand the new CDC recommendations the use case is "wear a cloth mask in public to prevent droplet spray from potential or asymptomatic spreaders." OK, great. Got it.

    So I'm in the grocery store, dutifully wearing my 3-layer cloth mask, and I have a violent sneeze. And I'm one of those people who may sneeze a few times in a row.

    Now what?

  6. #1506
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    Quote Originally Posted by Cougar View Post
    Come to think of it, not necessarily. Perhaps the HCQ somehow "shields" or coats the cells and tissues enough so that the virus is unable to attach, enter, and reproduce so easily, similar to the malaria parasite being unable to easily enter the red blood cells....... as well as making it more difficult for the immune system to attack the normal tissue (as with lupus)......
    The coating is what I have heard as well, which is why it's being used as a prophylactic.

    The following is hardly a medical paper/report but it's interesting and may offer some additional information, or may not since it's from The Diplomat.

    Quote Originally Posted by article
    Coronaviruses need an acidic environment to enter human cells. Chloroquine, being alkaline, blocks the virus by raising the body’s pH level. The drug also prevents the spike proteins on the outside of the virus from binding with a cell receptor by thwarting a process called “glycosylation.” More generally, chloroquine stimulates the immune system, which indirectly boosts the body’s ability to fight off a virus. Significantly, the drug provides this protection at two stages — before and after the cell is infected — indicating that it can be used as a prophylactic.
    I hope that info is true.

    The article addresses an early (Feb 4th) in-vitro study. The history of it is interesting, as well...

    Quote Originally Posted by article
    ...one of the authors was China’s “bat woman” Shi Zhengli, a formidable virologist and coronavirus expert who had assembled an encyclopedic database of bat-borne viruses over her decades-long career. She also led the team that first sequenced the genome of SARS-CoV-2 and identified the virus as a close relative of a coronavirus found in horseshoe bats of Yunnan.
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  7. #1507
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    The CDC cloth face mask recommendation is here, and is rather more lukewarm and limited than many journalists are suggesting.

    I've just read through their entire "Recent Studies" list (revealingly not called "References"), and can't glean much that supports even the limited recommendation that's been produced. All the studies are freely available on-line and easily retrieved by a search on their titles. I'd encourage those who are interested in this to take a look for themselves.

    Grant Hutchison

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    Are both the inlet and discharge to and from a N95 mask (or any other valved mask) filtered?
    I would assume not. If so then how effective would they be in preventing the infected individuals who are wearing them from infecting others who are not?
    Thanks.

    ETA A valve in a face mask can only make sense as a Check-Valve which works like a diode, allowing current in one direction while blocking it in the other.
    If both inlet and outlet are to be filtered, there world be no function for a valve, assuming bidirectional equivalence of filters used.

    ETA II
    The use of an exhalation valve reduces exhalation resistance, which makes it easier to breathe (exhale). Some users feel that a respirator with an exhalation valve keeps the face cooler and reduces moisture build up inside the facepiece.
    https://www.cdc.gov/niosh/npptl/topi...ealthcare.html

    ETA III How counterproductive is it for potentially asymptomaticly infected staff to wear such "comfortable" valved masks in hospitals and nursing homes? Could this be partly the reason for high infection and mortality rates in such establishments?
    Last edited by a1call; 2020-Apr-04 at 08:36 PM.

  9. #1509
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    For an N95 without a valve, you breathe in and out through the filter mask, which produces a rather uncomfortable feeling of resistance.
    If the N95 has an expiratory valve, it's just a valve, intended to reduce the work of breathing a little on expiration, and to stop the inside of the mask becoming uncomfortably humid, while ensuring the wearer still breathes in through the filter (assuming the mask has been properly fitted and tested).
    So, no, no expiratory filter on the valve. N95s are intended to protect the wearer, no-one else.

    Grant Hutchison

  10. #1510
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    Quote Originally Posted by grant hutchison View Post
    So, no, no expiratory filter on the valve. N95s are intended to protect the wearer, no-one else.
    Talk about false sense of security for others in the room.

  11. #1511
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    Quote Originally Posted by a1call View Post
    Talk about false sense of security for others in the room.
    Well, no-one would actually use an N95 with an EV to protect others from their own exhalations.
    It's not like people just buy boxes of these on the internet and have no idea how to use them. Oh wait.

    Grant Hutchison

  12. #1512
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    For the purpose of protecting others, would a scarf over the mouth and nose work? To me, it doesn't look like any sort of mask is really effective against a good cough or sneeze, but a barrier to slow that stuff down could be a little helpful.
    Solfe

  13. #1513
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    Quote Originally Posted by Solfe View Post
    For the purpose of protecting others, would a scarf over the mouth and nose work? To me, it doesn't look like any sort of mask is really effective against a good cough or sneeze, but a barrier to slow that stuff down could be a little helpful.
    Depends what you do with the scarf after you've spread your secretions on it. If you handle it and transfer virus to your hands, or lay it down and transfer virus to a surface, you might manage to infect more people than you potentially saved. This is the problem with all inexpert mask use--whether the infective particles are on the inside or the outside of the mask, poor handling and reuse means the mask can turn into just another way of transferring virus.
    (I watched a woman the other day, who pulled a loose-weave scarf over her face and coughed into it while holding it in place with her hand. I'd be keen not to handle the next door-handle she used.)

    Grant Hutchison

  14. #1514
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    Quote Originally Posted by grant hutchison View Post
    Depends what you do with the scarf after you've spread your secretions on it. If you handle it and transfer virus to your hands, or lay it down and transfer virus to a surface, you might manage to infect more people than you potentially saved. This is the problem with all inexpert mask use--whether the infective particles are on the inside or the outside of the mask, poor handling and reuse means the mask can turn into just another way of transferring virus.
    (I watched a woman the other day, who pulled a loose-weave scarf over her face and coughed into it while holding it in place with her hand. I'd be keen not to handle the next door-handle she used.)

    Grant Hutchison
    I saw someone out with a mask on at the grocery store. She touched a mailbox and a garbage can, then her brow or eyes. I didn't really see the point of the mask.

    What was especially odd about it was, the mask looked like the bottom half of a mask used in a spray booth. Usually there is eye protection, but she didn't have that part. Weird.
    Solfe

  15. #1515
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    Quote Originally Posted by grant hutchison View Post

    More recently, we have evidence from a case-control study of hospitalized patients, showing that the group whose disease stablized contained far fewer smokers than the group whose disease progressed.

    Grant Hutchison
    Now, back when doctors themselves smoked, wasn’t a sparing use of tobacco products looked at for cholitis?

    Fluid breathing doesn’t need to be rolled out in a big way-but I might have offered the option to badly needed medical personnel like Dr. Goodrich, who did surgical separations
    Last edited by publiusr; 2020-Apr-05 at 09:48 AM.

  16. #1516
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    Quote Originally Posted by Solfe View Post
    What was especially odd about it was, the mask looked like the bottom half of a mask used in a spray booth. Usually there is eye protection, but she didn't have that part. Weird.
    Perhaps home-made from a spray booth mask, in imitation of the appearance of un-visored masks. In terms of protecting yourself from coughed virus at close quarters, health care workers always use eye protection, too. But it's difficult to put up with for long, though, and worn incorrectly you can quickly end up with a fogged visor.

    Grant Hutchison

  17. #1517
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    Statistics: looking at deaths in the USA, upper respiratory tract is given as 41 per 100,000 slightly higher than strokes. Then influenza with pneumonia adds 14 per 100,000. Adding those for the population gives about 180,000 per year, USA, and these are the deaths which will accelerated by this virus. Plus some of course.

    Will this year’s figures attribute a high proportion to this pandemic? I guess that depends on testing positive at some point. But the focus is on the virus, so the news is totally dominated. Meanwhile nearly ten times as many will die of heart disease and cancer.

    No conclusion, just statistics.
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  18. #1518
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    Quote Originally Posted by publiusr View Post
    Now, back when doctors themselves smoked, wasn’t a sparing use of tobacco products looked at for cholitis?
    Do you mean colitis? There is some evidence that smoking can reduce symptoms of ulcerative colitis but can increase symptoms of Crohn’s colitis. Incidentally, Crohn’s colitis can be mistaken for ulcerative colitis. (I’m glad I don’t smoke.)

    I have no idea about other types of colitis (like NSAID induced colitis).

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  19. #1519
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    Quote Originally Posted by publiusr View Post
    Fluid breathing doesn’t need to be rolled out in a big way-but I might have offered the option to badly needed medical personnel like Dr. Goodrich, who did surgical separations
    The trouble with liquid ventilation is that it doesn't actually improve outcome in patients with Adult Respiratory Distress Syndrome (which seems to be what causes the severe lung problems of COVID-19). We were all excited about it during the 2000s, but like many apparently promising ICU interventions, it didn't survive first contact with the enemy. You're better off with Extracorporeal Membrane Oxygenation, which has demonstrated success.
    As for choosing who gets the last ECMO machine, the seventy-year-old skilled neurosurgeon or the thirty-year-old single parent, you probably don't want to think too hard about that if you want to sleep at night.

    Grant Hutchison

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    Google Community Mobility data, showing various behavioural changes in mobility in response to lockdowns. The downloaded files contain varying levels of granular data--I was able to look at what's been happening in my own town, for instance.

    Grant Hutchison

  21. #1521
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    Quote Originally Posted by grant hutchison View Post
    Google Community Mobility data, showing various behavioural changes in mobility in response to lockdowns. The downloaded files contain varying levels of granular data--I was able to look at what's been happening in my own town, for instance. Grant Hutchison
    Willing to bet Greenville and Greer, in Greenville Co., SC, have been super bad (very active).
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  22. #1522
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    Quote Originally Posted by grant hutchison View Post
    ... it didn't survive first contact with the enemy. ...
    Ah, Gen. Helmuth Von Moltke. Wise man.

    ETA:

    Quote Originally Posted by Roger E. Moore View Post
    Willing to bet Greenville and Greer, in Greenville Co., SC, have been super bad (very active).
    The project I started just before "all this" is using an engineering company with some folks working in Greenville. When we started they were in-office; I think they're now all remote.
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  23. #1523
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    Quote Originally Posted by Jim View Post
    Ah, Gen. Helmuth Von Moltke. Wise man.
    Oh, yes. His "strategy is a system of expedients" has relevance here, too.

    Grant Hutchison

  24. #1524
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    There was a tv news interview with a NJ teacher making face shield frames using his 3D printer. I think I recall that he has made 300 and has a backlog of 600 orders. He has plenty of donations so he likely will have a 2nd printer. Others, hopefully will do the same.

    The shield seems superior to a cloth covering if the idea is to avoid projectile droplets, but is it? What would be the best way to use this in the workplace and public?

    Some more graphs.

    World rates thru Apr 4.jpg
    7 Cntry Avg thru Apr 4.jpg
    US dual thru Apr 4.jpg

    The 7-country average percent rate chart is corrected since it is now based on actual counts rather than averaging percentages themselves. The very large jump in the report from France in their case numbers reminded me I was not representing accurately the rate increase/decrease for each day. [Added: Disregard the "Average" in the header for the world chart.]
    Last edited by George; 2020-Apr-05 at 10:23 PM.
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  25. #1525
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    Quote Originally Posted by schlaugh View Post
    So if i understand the new CDC recommendations the use case is "wear a cloth mask in public to prevent droplet spray from potential or asymptomatic spreaders." OK, great. Got it.

    So I'm in the grocery store, dutifully wearing my 3-layer cloth mask, and I have a violent sneeze. And I'm one of those people who may sneeze a few times in a row.

    Now what?
    Bring a spare mask and a ziplock bag. Put used mask in bag and run from the mob carrying the pitchforks* and torches.


    ————-
    * Why random suburbanites own pitchforks is an exercise for the reader.
    Information about American English usage here. Floating point issues? Please read this before posting.

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  26. #1526
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    Quote Originally Posted by schlaugh View Post
    So I'm in the grocery store, dutifully wearing my 3-layer cloth mask, and I have a violent sneeze. And I'm one of those people who may sneeze a few times in a row.


    Now what?
    Well here are some scientific things to consider.
    In east Asian countries, there’s a superstition (this Is probably a typo) that if you sneeze, someone is talking about you. Moreover, the number of times you sneeze is a sign as to what they’re talking about. For example, one sneeze means something good has been said, two means something bad has been said, three is a sign that someone is in love with them, and four is a sign that tragedy will befall their family.
    https://www.ceenta.com/news-blog/6-myths-superstitions-and-more-about-sneezing
    If that's too specific for you to be true, then fine make an appointment with your doctor to remedy your allergy.
    Also, next time please face away from your computer when you sneeze. You don't want to make us all sick with allergies.



    Last edited by a1call; 2020-Apr-05 at 07:39 PM.

  27. #1527
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    Really good Youtube explaining the mechanisms and effects is here:

    https://www.youtube.com/watch?time_c...ture=emb_title

    I think it covers a lot of ground and wraps it into a nice compact nutshell .. Feel free to spread this one around!

  28. #1528
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    Quote Originally Posted by Selfsim View Post
    Really good Youtube explaining the mechanisms and effects is here:
    "Mechanisms and effects" of the virus?
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  30. #1530
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    I'm going to hate it when COVID-19 shows up again this fall, alongside the flu, and we go through this all over again.

    What are the chances of comorbidity, I wonder.
    Do good work. —Virgil Ivan "Gus" Grissom

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