Page 68 of 75 FirstFirst ... 18586667686970 ... LastLast
Results 2,011 to 2,040 of 2221

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

  1. #2011
    Join Date
    Dec 2011
    Location
    Very near, yet so far away
    Posts
    377
    Quote Originally Posted by grant hutchison View Post
    Here's a tiny url link to the above article, which solves the net nanny corruption of the original url: https://tinyurl.com/ycj5t9zy

    Grant Hutchison
    Thanks, that was a good read. A couple of things I would add to the "what scientific tool should people try and use to make sense of it all" question are:

    (a) not believe anything reported by the media until it's been verified,

    and

    (b) practice patience. If an alarming report comes out, take it for what it is, just a report. If its true and relevant, it will become obvious. No point winding yourself up over a possibility. Very often todays press panic is forgotten tomorrow.

    Also, comparing reports from different sources always gives perspective.

  2. #2012
    Join Date
    Aug 2003
    Location
    The Wild West
    Posts
    9,491
    Quote Originally Posted by grant hutchison View Post
    Here's a tiny url link to the above article....
    Quote Originally Posted by The Article
    Once you put a model out there that then creates changes in behavior that pull you out of the domain that the model was trying to model in the first place....
    Hmm. Sort of like the Observer Effect in quantum mechanics.
    Everyone is entitled to his own opinion, but not his own facts.

  3. #2013
    Join Date
    Apr 2005
    Posts
    2,615
    Testing the association between blood type and COVID-19 infection, intubation, and death

    Update on the blood groups associations with risk in Covid-19 infection.

    As reported previously A and B are at greater risk than O. However look at Table 1 in the linked document.

    Groups A Rh-neg and B Rh-neg are NOT at increased risk. It is only the Rh-positive A and B groups that are.

    In fact the authors do not seem to realise what is the biggest factor staring them in the face, and that is the rhesus factor.

    See the paper and see what you think.

    https://www.medrxiv.org/content/10.1...073v1.full.pdf

  4. #2014
    Join Date
    Jul 2005
    Posts
    19,277
    They actually comment extensively on the increased risk associated with Rh+ throughout the paper. Indeed, they stratified by Rh in order to tease out the other associations. Look at the last line of the paper:
    Our results replicate previously-discovered associations between A and O blood groups and COVID-19, and we show novel association between B, AB and Rh blood groups.
    My bold. That seems clear enough.

    Grant Hutchison

  5. #2015
    Join Date
    Jul 2005
    Posts
    19,277
    Quote Originally Posted by Selfsim View Post
    Looks like Remdesivir has flopped also ('accidental' preliminary media release of the study, only, is available)
    Highly preliminary results from the ACTT trial suggest some small benefit of Remdesivir in terms of reduced recovery time and mortality. The results still need to be submitted and peer-reviewed.

    Grant Hutchison

  6. #2016
    Join Date
    Mar 2004
    Posts
    18,939
    For those interested, here is an article on some of the drugs, treatments, and vaccines being tested for Covid-19:

    https://www.politico.com/news/2020/0...accines-211416

    Aside from vaccines, treatment research seems to be focused on antivirals, immune modulators that reduce certain kinds of immune system overreactions (like a cytokine storm) and dealing with some of the other severe effects seen from an infection (I’m seeing excessive clotting and microthrombi mentioned more often now).

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." — Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

  7. #2017
    Join Date
    Jun 2004
    Location
    The Great NorthWet
    Posts
    15,534
    Quote Originally Posted by kzb View Post
    Testing the association between blood type and COVID-19 infection, intubation, and death

    Update on the blood groups associations with risk in Covid-19 infection.

    As reported previously A and B are at greater risk than O. However look at Table 1 in the linked document.

    Groups A Rh-neg and B Rh-neg are NOT at increased risk. It is only the Rh-positive A and B groups that are.

    In fact the authors do not seem to realise what is the biggest factor staring them in the face, and that is the rhesus factor.

    See the paper and see what you think.

    https://www.medrxiv.org/content/10.1...073v1.full.pdf

    Oh great. I'm A-. But my wife is A+ and has multiple other risk factors. She hasn't been out of the house in a month but what if I bring something back?
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  8. #2018
    Join Date
    Aug 2013
    Posts
    586
    If you are interested in how the Covid 19 tracing apps work there is a good general article here. https://isc.sans.edu/forums/diary/Pr...xposure/26066/

  9. #2019
    Join Date
    Jul 2005
    Posts
    19,277
    New Scientist reported last week (issue of 25 April) that modelling suggests you need about 80% of smartphone users in the UK to use the app for it be effective, that about 74% express willingness to use such an app, and that in Singapore (a strongly compliant society) only about 17% of users actually did download the app.
    Wandering around with bluetooth activated on your phone in public places is a significant security risk, and with the app providing no personal advantage (it doesn't stop you getting the disease) I can see why it would be a hard sell.

    Grant Hutchison

  10. #2020
    Join Date
    Apr 2011
    Location
    Norfolk UK and some of me is in Northern France
    Posts
    9,154
    In France you need a form to be free to go out. I can see a possibility of conditional licence using the app and a mask, for example. I imagine the remote detection of the app is technically possible using bluetooth. Normally it would be unthinkable for the state to do that but the incentive is there. I have not seen a publication of the results of that town in Germany where everyone was required to mask up. At the time it seemed very effective, I wonder what happened next.
    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

  11. #2021
    Join Date
    Jul 2005
    Posts
    19,277
    Quote Originally Posted by profloater View Post
    I have not seen a publication of the results of that town in Germany where everyone was required to mask up. At the time it seemed very effective, I wonder what happened next.
    Jena maintains its own Covid webpage--you can follow their daily data here. Unfortunately, so many other things changed at the same time it's difficult to tease out a specific effect for the facemasks.
    The recent mask legislation in Germany may give us some actual useful results, given how closely Germany is tracking R0--it might be possible to tease a signal for masks out of that produced by other measures.
    We do have a huge database from 1918-19, when mask use was so mandatory in parts of the USA that people were being shot in the streets for not complying, but it's pretty uncontrolled, and people can pick anecdotes to suit either side of the argument.

    Grant Hutchison

  12. #2022
    Join Date
    Apr 2005
    Posts
    2,615
    Quote Originally Posted by grant hutchison View Post
    They actually comment extensively on the increased risk associated with Rh+ throughout the paper. Indeed, they stratified by Rh in order to tease out the other associations. Look at the last line of the paper:My bold. That seems clear enough.

    Grant Hutchison
    Well, in Table 1 there is a row for each ABO blood type, a row for A, a row for B and a row for O (also AB although that was not included in their analysis).

    There are rows under each where the numbers are split between Rh-positive and Rh-negative.

    But there are not rows for Rh-positive and Rh-negative, or rows underneath each where is split into ABO numbers.

    Then again if you did this there would be only one death in the Rh-neg group across all ABO blood groups. Maybe poor statistics but this is what jumped out to me. One out of 45 Rh-neg individuals (2.2% mortality) died compared to 79 out of 637 Rh-positives (12.4% mortality). But they concentrate their comments on the ABO differences, which are much smaller.

  13. #2023
    Join Date
    Jul 2005
    Posts
    19,277
    Quote Originally Posted by kzb View Post
    Well, in Table 1 there is a row for each ABO blood type, a row for A, a row for B and a row for O (also AB although that was not included in their analysis).

    There are rows under each where the numbers are split between Rh-positive and Rh-negative.

    But there are not rows for Rh-positive and Rh-negative, or rows underneath each where is split into ABO numbers.

    Then again if you did this there would be only one death in the Rh-neg group across all ABO blood groups. Maybe poor statistics but this is what jumped out to me. One out of 45 Rh-neg individuals (2.2% mortality) died compared to 79 out of 637 Rh-positives (12.4% mortality). But they concentrate their comments on the ABO differences, which are much smaller.
    No, they're very clear about the effect of Rhesus.
    When we tested individual ABO+Rh blood groups against all others, we discovered that strong associations are only found in Rh positive blood groups
    Our results from NYP/CUIMC identified significant associations between A, AB, and O bloodgroups. However, further stratifying by Rh resulted in significant associations for A+ and O+only. Negative Rh blood groups are less common in our data, representing only 9.25% of individuals, so the lack of evidence for association with negative blood types could be due to lower sample sizes. Yet, odds ratios for ABO groups A and O are less extreme than the associated ABO+Rh blood groups (A+, O+), and the corresponding negative blood groups (A-,O-) have (insignificant) odds in the opposite directions as their positive counterparts.
    By bold throughout. They clearly state, multiple times, that Rhesus is important, and it's evident from their odds ratios and significance values in their tables why they keep pointing that out. They have a statistical problem because of low numbers in Rh negative, which means they don't hit significance with the reversed odds ratio in Rhesus negative, but they've essentially done the job by pointing out that the risk is only present in the Rhesus positive stratum, and they point that out quite clearly.

    Grant Hutchison

  14. #2024
    Join Date
    Jun 2005
    Posts
    1,869
    One might think that it would be easy finding the source of the only (known) infection in a remote Arctic territory with a population of 1.6k. but no:

    "We don't know yet the full details of how this individual got COVID-19," Patterson added at a morning press conference.
    https://www.cbc.ca/news/canada/north...case-1.5509014

    Nunavut has an area of 2M+ km^2 (bigger than France) with a population of 38k.

  15. #2025
    Join Date
    Jul 2005
    Posts
    19,277
    South Korea now confirms, predictably but perhaps reassuringly, that patients said to have had an episode of Covid reinfection/reactivation on the basis of PCR testing were simply shedding viral RNA and were not infective on viral culture. I've been unable to find a scientific publication so far, but here's an article from the Korea Herald. (Beware the use of the phrase "false positive" in this context. The PCR test is a true positive for viral RNA, it simply doesn't tell you if there are viable virions present, so the use of the phrase "false positive" is a bit misleading.)

    Grant Hutchison

  16. #2026
    Join Date
    Sep 2004
    Posts
    4,912
    Quote Originally Posted by grant hutchison View Post
    South Korea now confirms, predictably but perhaps reassuringly, that patients said to have had an episode of Covid reinfection/reactivation on the basis of PCR testing were simply shedding viral RNA and were not infective on viral culture. I've been unable to find a scientific publication so far, but here's an article from the Korea Herald. (Beware the use of the phrase "false positive" in this context. The PCR test is a true positive for viral RNA, it simply doesn't tell you if there are viable virions present, so the use of the phrase "false positive" is a bit misleading.) Grant Hutchison
    Thank you, good to know.
    Do good work. —Virgil Ivan "Gus" Grissom

  17. #2027
    Join Date
    Dec 2011
    Location
    Very near, yet so far away
    Posts
    377
    There is a paper out from the New England Journal of Medicine which purports to demonstrate that Covid-19 can remain viable as an aerosol for at least 3 hours in the air.

    I don't have any reason to dispute the findings apart from questioning the relevance of the findings to the real world.
    From the paper:
    Aerosols (<5 μm) containing SARS-CoV-2 (105.25 50% tissue-culture infectious dose [TCID50] per milliliter) or SARS-CoV-1 (106.75-7.00 TCID50 per milliliter) were generated with the use of a three-jet Collison nebulizer and fed into a Goldberg drum to create an aerosolized environment. The inoculum resulted in cycle-threshold values between 20 and 22, similar to those observed in samples obtained from the upper and lower respiratory tract in humans.
    Now, what size is the Goldberg drum? What kind of environment have they created? From my cursory investigation it appears a Goldberg drum rotates, which helps to prolong an aerosol environment for sustained study. How is this relevant to a person walking on the street?

    Surely the aerosol will be dispersed and drop out of the air much more quickly in a non-laboratory environment?

  18. #2028
    Join Date
    Aug 2005
    Location
    NEOTP Atlanta, GA
    Posts
    3,160
    I don’t have a Goldberg drum for lungs or a laboratory nebulizer in my olfactory system. What in the world are they trying to prove?

  19. #2029
    Join Date
    Jul 2005
    Posts
    19,277
    Quote Originally Posted by headrush View Post
    There is a paper out from the New England Journal of Medicine which purports to demonstrate that Covid-19 can remain viable as an aerosol for at least 3 hours in the air.
    Scroll down to the letters section on the same page to see a succession of responses which raise the same doubts you do.
    This has more relevance to aerosol generating procedures in hospitals, than it does to community transmission.

    Grant Hutchison

  20. #2030
    Join Date
    Aug 2003
    Location
    The Wild West
    Posts
    9,491
    Quote Originally Posted by grant hutchison View Post
    ...patients said to have had an episode of Covid reinfection/reactivation on the basis of PCR testing were simply shedding viral RNA and were not infective on viral culture....
    I'm not following the terminology here. Are the patients testing positive but not having symptoms, or they are having symptoms? "Shedding viral RNA" seems to mean they are contagious and spreading the disease, but then what does it mean that they are not infectious on viral culture?
    Everyone is entitled to his own opinion, but not his own facts.

  21. #2031
    Join Date
    Jul 2005
    Posts
    19,277
    Quote Originally Posted by Cougar View Post
    I'm not following the terminology here. Are the patients testing positive but not having symptoms, or they are having symptoms? "Shedding viral RNA" seems to mean they are contagious and spreading the disease, but then what does it mean that they are not infectious on viral culture?
    The infective agent for a virus is the virion, which is viral RNA enclosed in a capsule that lets it invade cells. Viral RNA on its own has no way to get into cells, and therefore is not infective. But if the virion can inject viral RNA into cells, then the viral RNA can trick the cells into producing more virions. And that's an infection.
    When we recover from a viral infection, some of our cells continue to leak viral RNA, but no infective virions. This is well-known, and not some unique property of SARS-CoV-2. Some people can leak viral RNA from dying cells for many weeks. A PCR test, which is the standard test for the presence of infection in symptomatic people, only detects viral RNA. It has no way of knowing if that viral RNA is packaged up in infective virions, or is just debris leaking from dying cells.
    If someone has symptoms of COVID-19, and has viral RNA in their secretions, it's a fairly safe bet they're actually producing infective virions. But some people who recover symptomatically from COVID-19 still produce detectible viral RNA in their secretions for several weeks. So the worry was that these people had either not cleared the virus and were still infective (that they were convalescent carriers) or (on rare occasions when they developed new symptoms, returned to hospital and tested positive again) that they had been reinfected (that is, had not become immune from first exposure to the disease). Both of these outcomes have been reported, albeit rarely.
    The only way to find out the infective significance of the viral RNA being detected by the standard PCR tests in these patients is to added the patient's secretions to a culture medium (provide it with actual cells it can invade) and see if the virus reproduces. That way we can tell non-infective viral RNA from infective virions. (The reason viral culture is not the standard test is because it's complicated and it takes a long time to get a result.)

    So the South Koreans are reporting that their COVID-19 patients with prolonged positive PCR tests for viral RNA are not showing any viable virions when followed up with viral culture. Which is good news.

    Grant Hutchison

  22. #2032
    Join Date
    Jan 2004
    Location
    No longer near Grover's Mill
    Posts
    5,200
    Grant- thank you for that last post. I now have a much better understanding of the situation.


    Sent from my iPhone using Tapatalk
    I may have many faults, but being wrong ain't one of them. - Jimmy Hoffa

  23. #2033
    Join Date
    Aug 2003
    Location
    The Wild West
    Posts
    9,491
    Quote Originally Posted by grant hutchison View Post
    ...The only way to find out the infective significance of the viral RNA being detected by the standard PCR tests in these patients is to add the patient's secretions to a culture medium (provide it with actual cells it can invade) and see if the virus reproduces.
    Ah. Yes, "on viral culture" had me thrown. Well, among other things, lol. Perfect explanation. Thanks!
    Everyone is entitled to his own opinion, but not his own facts.

  24. #2034
    Join Date
    Sep 2003
    Posts
    13,162
    Quote Originally Posted by grant hutchison View Post
    The infective agent for a virus is the virion, which is viral RNA enclosed in a capsule that lets it invade cells. Viral RNA on its own has no way to get into cells, and therefore is not infective. But if the virion can inject viral RNA into cells, then the viral RNA can trick the cells into producing more virions. And that's an infection.
    Thanks Grant for that helpful information. Would something like a naval mine be a fair analogy where the viral RNA is the explosive and the mine's housing ("capsule") the means to keep its contents deliverable and effective?
    We know time flies, we just can't see its wings.

  25. #2035
    Join Date
    Jul 2005
    Posts
    19,277
    Quote Originally Posted by George View Post
    Thanks Grant for that helpful information. Would something like a naval mine be a fair analogy where the viral RNA is the explosive and the mine's housing ("capsule") the means to keep its contents deliverable and effective?
    I think that's actually a pretty bad analogy, and I don't think we need an analogy.

    Grant Hutchison

  26. #2036
    Join Date
    Jun 2006
    Posts
    4,832

    Try Again

    Here is another covid discussion that is above the Joe Sixpac level:

    https://www.youtube.com/watch?v=EUS_qi6BvUQ

    I hope it does not generate the same vituperative reaction as the last one. The interviewee is a highly placed physician from Columbia Univerity.

    Thanks, John M.
    I'm not a hardnosed mainstreamer; I just like the observations, theories, predictions, and results to match.

    "Mainstream isn’t a faith system. It is a verified body of work that must be taken into account if you wish to add to that body of work, or if you want to change the conclusions of that body of work." - korjik

  27. #2037
    Join Date
    Dec 2011
    Posts
    3,567
    Goes some way in explaining serotology testing concerns, wrt proportions of false positives and apparently asymptomatic past case infections:

    F.D.A. Orders Companies to Submit Antibody Test Data
    The F.D.A.’s action follows a report by more than 50 scientists, which found that only three out of 14 antibody tests gave consistently reliable results, and even the best had flaws. An evaluation by the National Institutes of Health has also found “a concerning number” of commercial tests that are performing poorly, the agency said.

    Around the globe, government and health officials have hoped that antibody tests would be a critical tool to help determine when it would be safe to lift stay-at-home restrictions and reopen businesses.
    FDA announcement link here:
    Ideally, performance characteristics are established in a clinical study with prospective samples. If a prospective study is not feasible, an acceptable alternative would be to test retrospectively collected SARS-CoV-2 antibody positive specimens from patients that have been previously confirmed infected by SARS-CoV-2 RT PCR, accompanied by basic information such as the population from which the sample was drawn and the comparator method, specimen collection date, date of onset of symptoms (if present/known), and comparator method to confirm patients as SARS-CoV-2 infected or not infected (see above).

    Clinical agreement data should be provided using at least 30 antibody positive samples for each immunoglobulin claimed and 75 antibody negative samples from patients tested for SARS-CoV-2 and confirmed as negative and the data should demonstrate a minimum overall 90.0% positive percent agreement and overall 95.0% negative percent agreement, and for tests that report specifically IgM and IgG results, a minimum positive percent agreement for IgM of 70% and a minimum positive percent agreement for IgG of 90%. Point estimates not lower than 93% for combined NPA, not lower than 90% for combined PPA, and for tests that specifically report IgG or IgG and IgM, PPA for IgG not lower than 87%, and PPA for IgM not lower than 67% may be acceptable if a larger number of samples are evaluated and the lower bounds of the 95% confidence intervals are higher than would be demonstrated in a clinical agreement study with 30 antibody positive and 75 antibody negative samples.

    If a claim for fingerstick is desired, we believe evaluating a minimum of 30 positive and 30 negative fingerstick whole blood samples may be acceptable to demonstrate clinical performance in fingerstick samples.

  28. #2038
    Join Date
    Dec 2011
    Posts
    3,567
    Quote Originally Posted by grant hutchison View Post
    The infective agent for a virus is the virion, which is viral RNA enclosed in a capsule that lets it invade cells. Viral RNA on its own has no way to get into cells, and therefore is not infective. But if the virion can inject viral RNA into cells, then the viral RNA can trick the cells into producing more virions. And that's an infection.
    When we recover from a viral infection, some of our cells continue to leak viral RNA, but no infective virions. This is well-known, and not some unique property of SARS-CoV-2. Some people can leak viral RNA from dying cells for many weeks. A PCR test, which is the standard test for the presence of infection in symptomatic people, only detects viral RNA. It has no way of knowing if that viral RNA is packaged up in infective virions, or is just debris leaking from dying cells.
    If someone has symptoms of COVID-19, and has viral RNA in their secretions, it's a fairly safe bet they're actually producing infective virions. But some people who recover symptomatically from COVID-19 still produce detectible viral RNA in their secretions for several weeks. So the worry was that these people had either not cleared the virus and were still infective (that they were convalescent carriers) or (on rare occasions when they developed new symptoms, returned to hospital and tested positive again) that they had been reinfected (that is, had not become immune from first exposure to the disease). Both of these outcomes have been reported, albeit rarely.
    Footnote:

    Whilst this explanation may be considered reasonably accurate as far as the SARS-CoV-2 virus is concerned, it certainly cannot be taken as applying for the behaviors of all virus types (as the generalisations made in the above text, imply).

  29. #2039
    Join Date
    Jul 2005
    Posts
    19,277
    Quote Originally Posted by Selfsim View Post
    Footnote:

    Whilst this explanation may be considered reasonably accurate as far as the SARS-CoV-2 virus is concerned, it certainly cannot be taken as applying for the behaviors of all virus types (as the generalisations made in the above text, imply).
    I made one deliberate omission which I don't think will confuse anyone, but otherwise on rereading I still think it's a reasonable short summary. What concerns you?

    Grant Hutchison

  30. #2040
    Join Date
    Dec 2011
    Location
    Very near, yet so far away
    Posts
    377
    With regard to smoking and under-representation of smokers in covid19 cases. It occurred to me that maybe it is the suppression of the immune system experienced by smokers that is preventing an overreaction to the virus. Prevention of the cytokine storm scenario may lead to a better outcome. I'm not sure how to square that possibility with the danger faced by immune deficient patients. Possibly a reduced but not entirely eliminated immune response. I've not heard of any results from the French nicotine patch trials yet.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •