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  1. Join Date
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  2. Join Date
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    #18602
    Quote Originally Posted by Deestone View Post
    Doc may I know what is antigen and how does it relate to antibodies? and what is the difference between rapid antibody and swab antigen I know that rapid antibody detects your anitbodies that your body produces in response to an infection but have no knowledge on antigens.

    Sent from my SM-N910C using Tapatalk
    first off, these two statements say it all for covid:
    a negative antibody test should not be equated with absence or presence of the virus in the body.
    neither should a positive antibody test be equated with the presence or absence of the virus in the body.

    "ANTIGEN" refers to the virus itself or parts of it.
    a number of PCR tests are designed to detect the spike protein, the nucleic acid, or other components of the covid virus. the test material is usually from a (painful) a swab of the patient's posterior nasopharyngeal wall.
    because of the intricacies of the testing procedure, detection of covid virus antigens is traditionally slow, requiring several hours of table work.
    a problem we now realize, is that even as the virus is already dead or non-viable, some of these virus components may be still around, and might detected by the test, resulting in a "false positive" result.
    there are more rapid tests emerging now, needing 30-60 minutes only. there are even the more convenient rapid saliva tests that are promising to be potentially as good as the traditional gold-standard PCR.

    when our immune system detects the virus, they manufacture "ANTIBODIES".
    antibodies are proteins that correspond to the virus. they are very specific, akin to the specificity of keys to their padlocks.
    but... just like keys and padlocks... sometimes, just sometimes, another key might be able to open its un-intended padlock. the so-called "cross-reaction".
    (OT. do we remember the 80s, where it was rumored that a lancer key could open one in eight lancers in the parking lot? heh heh.)
    antibody tests are much easier to effect. by the nature of the test, they are rapid, needing just minutes instead of hours.
    we are familiar with antibody testing, as many laboratory tests are based on them... pregnancy test.. typhoid test.. hepatitis test.. dengue test..

    even now,
    effectivity of experimental vaccine action is partially dependent on level of antibody induced in the subject's blood.

    "rapid test" used to be antibody test only, because the gold-standard traditional PCR test is slow.
    but there are now "rapid PCR tests" in the pipeline.
    we have but to ask, what it is we are getting.

    btw,
    "RT-PCR" does not mean rapid test PCR. RT-PCR still is the traditional PCR we read about. it means, "Reverse Transcription PCR", which is just a lengthier, more descriptive name of what the test is all about.

    so,
    why is there confusion between antibodies, antigens, and the presence of disease?
    ganito yan.

    antigen is the microbe itself, virus or bacterium, or parts of it.
    a positive result means that the virus or bacterium, or parts of it, is still in the body.
    normally, this means, active disease. "may sakit kah, at nakakahawa kah."

    if the antibody test is done and it is reactive ("positive"),
    it means the body has antibodies, because it has been exposed to the virus or bacterium. remember also, that vaccination can give the same result.
    hindi nakakahawa kung antibodies lang.

    problems in patient status (not infected, infected, recovered) arise because:
    1. there is a time lag between infection, recovery, and antibody level;
    2. antigen-antibody curves can overlap, providing no 100% clear delineation among the patient statuses.

    in a study done by the pgh folks,
    it showed that the predictive value of antibody testing for the presence of the virus, is a measely 20%.

    to re-iterate,
    a positive or negative antibody test result should not be equated with absence or presence of the virus.
    Last edited by dr. d; October 21st, 2020 at 12:04 PM.

  3. Join Date
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    #18603
    Quote Originally Posted by Deestone View Post
    I see but we still have rapid testing.... I just don't get the point why do we need still to have rapid testing then if positive IGM then we go on swab antigen. We can go directly go to swab antigen test right? How much does swab antigen cost is it not costly as pcr? I dont know the brand that we use because It is in the other building and havent went through swab antigen test myself.

    Sent from my SM-N910C using Tapatalk
    yes rapid test din naman ang antigen test

    pareho lang sa rapid antibody test -- ilan minuto lang ang result

    price halos pareho lang sa antibody test siguro mas mahal konte

    malayo sa price ng PCR

  4. Join Date
    Nov 2005
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    #18604
    Deestone,

    antibodies are produced by the body to fight the virus

    kaya ginamit ang antibody test to see if you're infected -- IGM = infected, still fighting

    IGG = finished fighting

    ang problema kasi pag newly infected ka di agad meron antibodies

    it takes days to develop IGM so madami false negative (wala antibodies pero may virus)

    so ngayon mas prefer ang antigen test coz it detects the virus directly

    ang problema naman sa rapid antigen test di sya kasing sensitive ng PCR so if you have low level of virus maari di madetect ng rapid antigen test

  5. Join Date
    Nov 2005
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    45,927
    #18605
    also nakakainis din ung positive ka sa IGG tapos i-quarantine ka and ipa-swab test pa (PCR)

    eh IGG na nga magaling ka na dapat di ka na i-quarantine and di na kailangan i-swab di ka na nakakahawa

    kaya fallen out of favor ang rapid antibody test

  6. Join Date
    Sep 2003
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    #18606
    PH active cases looks like it got zapped compared to other active chart...
    Last edited by Monseratto; October 21st, 2020 at 01:07 PM.

  7. Join Date
    Mar 2008
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    52,517
    #18607
    here's a thought.
    are all antibodies, protective? what if the antibodies are mere marker antibodies?
    do all covid patients develop antibodies?
    covid is a novel disease.
    more research needed...

  8. Join Date
    Jul 2004
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    #18608
    Hmmm, China and Brazil in the same sentence and together on the results of the trials somehow does not give me confidence on the efficacy of the vaccine


  9. Join Date
    Sep 2003
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    #18609
    Human Challenge


  10. Join Date
    Mar 2008
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    #18610
    Quote Originally Posted by Monseratto View Post
    Human Challenge

    what is the compensation package?
    do my heirs get a handsome lifetime (theirs, not mine!) pension?
    heh heh.

China Corona Virus Outbreak