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Medicine

People Testing Negative For COVID-19 Antibodies May Still Have Some Immunity, Study Suggests (bbc.com) 56

Thelasko shares a report from the BBC: For every person testing positive for antibodies, two were found to have specific T-cells which identify and destroy infected cells. This was seen even in people who had mild or symptomless cases of Covid-19. But it's not yet clear whether this just protects that individual, or if it might also stop them from passing on the infection to others.

Researchers at the Karolinksa Institute in Sweden tested 200 people for both antibodies and T-cells. Some were blood donors while others were tracked down from the group of people first infected in Sweden, mainly returning from earlier affected areas like northern Italy. This could mean a wider group have some level of immunity to Covid-19 than antibody testing figures, like those published as part of the UK Office for National Statistics Infection Survey, suggest. It's likely those people did mount an antibody response, but either it had faded or was not detectable by the current tests. And these people should be protected if they are exposed to the virus for a second time.

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People Testing Negative For COVID-19 Antibodies May Still Have Some Immunity, Study Suggests

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  • Sounds scientifically complex and yet indeterminate. Has that lawyer, after the necessary scientific putting on the black robe and sitting on a raised pedestal in Dover, ruled on the final science yet? [discovery.org]

    Just want to make sure I'm following the True Lawyer Science.

    • by dgatwood ( 11270 ) on Wednesday July 01, 2020 @10:06PM (#60252668) Homepage Journal

      Immunology is complex and indeterminate. We know, for example, that the first flu virus you're exposed to as a kid confers partial immunity to that subtype of flu for the rest of your life, even across huge mutations. So if your first flu strain was an H3N1, you'll get a milder case of any H3N1 strain for the rest of your life [www.nhs.uk] than someone whose first flu as a kid was an H1N1 strain.

      This is likely similar. Folks whose first coronavirus strain was in some way outwardly similar to this one might have a stronger immune response to this strain than folks who have never had coronavirus or whose first coronavirus strain was less similar.

      This is, of course, pure speculation on my part.

      • by Rei ( 128717 )

        I'm not sure how strong the science on such a "first flu" effect is, but it's quite true that varying levels of immunity can last for a life time. When the "Asian Flu" hit, for example, the only people with any immunity were those who had caught the "Russian Flu" as children six decades prior.

        It's important to note that this disease isn't just caused by "a coronavirus". Coronaviridae is a whole family. SARS and COVID-19 (but not MERS) are specifically caused by sarbecoviruses (the sane species, even, just

  • by h33t l4x0r ( 4107715 ) on Wednesday July 01, 2020 @10:22PM (#60252688)
    Are going to have to admit that they have no idea how anything really works.
    • by Anonymous Coward

      Are going to have to admit that they have no idea how anything really works.

      I honestly believe that the pre-req for medical school should be a degree in physics.
      That degree makes it so much easier to say you don't know how something works.

    • MDs are mechanics that work on fixing you, which generally is fluids and rest. PhDs are the engineers of the analogy that figure out how this stuff works.
  • I didn't want to submit a whole Ask Slashdot on this, but some of the Arizona numbers https://azdhs.gov/preparedness... [azdhs.gov] aren't making sense to me.

    For example today's total cases (84,092) are several thousand larger than the number of positive tests (73,642, 721,985 tests with a 10.2% total positive rate). They are supposedly defining a case as an individual so any retesting of the same person should add to the total test count, but not the case count. It seems like the cases should be a smaller number tha

    • by dgatwood ( 11270 )

      Probably differences in reporting path. There are at least a couple of different ways that cases get reported, and one of those paths lags a couple of weeks behind the other one.

      • I guess that's possible, but I would have figured the test results would be reported more quickly than case status. Case status has multiple variables to consider and the test outcome is a prerequisite. So if there was a significant delay in reporting, it should show tests leading cases, not the other way around.

        • by dgatwood ( 11270 )

          I would have thought so, too, but I try never to underestimate how slowly the wheels of the federal government can turn. :-D

          But seriously, what may be compounding the problem is that test results for multiple patients have to be correlated to ensure that they aren't being reported positive more than once, and they only just started trying to do that recently. So that could be putting a serious kink in their reporting right now.

    • I can’t speak to Arizona, and I am too lazy to try to figure it out... but based on what I see in Hawaii there are a number of different types of numbers that get reported.

      The number of tests is likely the sum total of tests performed within the state. The number of cases will include Arizona residents tested out-of-state; the same can be the case for hospitalizations out-of-state.

      There is also the fun fact that initially a positive test is generally assigned to in-state, but follow-up may reveal it

      • Interesting. I don't exactly know what to make of that. Arizona definitely has a large contingency of part time residents (snow birds), so that could be a contributor. Not sure which way it would tend to move the numbers, though. It depends on how many people either didn't leave who were already here and how many didn't come due to the pandemic.

        Unfortunately the CDC and azdhs numbers appear to be the best I can find so far. I'll have to dig into the less public epidemiology sources at local universitie

  • two were found to have specific T-cells. That's amazing.

    • by Rei ( 128717 )

      I can't tell if this is sarcasm or not. Poe's law?

      T8 "killer" T-cells are not identical. The immune system beaks the rule that all healthy cells in a person's body apart from germ cells have the same genetics. Narrow sections of the DNA are designed to shuffle rapidly under certain conditions, which allows the cells to create proteins in pretty much any arrangement, rather than being locked to a narrow subset (as would be the limit from a fixed genome). With T8 cells, they're "trained" (selected) in the th

  • by ModelX ( 182441 ) on Thursday July 02, 2020 @05:33AM (#60253408)

    Any one looking at the numbers seriously must ask themselves:
    - who tests the tests ?
    - what is the share of false positives ?
    - what is the share of false negatives ?
    - how about the share of false positives/negatives with the known presence of a very similar virus ?
    - how do we know that the specific antibodies are specific to this variant of the virus and universal across people with different immune systems and different prior exposures ?
    - how can we exclude other antibody variants from interfering with this specific virus ?

    Without these answers at best we can look at these articles as some kind of pseudo-scientific garbage-in garbage-out with unknown bias.

  • The first thing we need to do to combat this virus is get rid of Donald Trump. He's the biggest impediment to progress and saving lives
  • https://www.zmescience.com/sci... [zmescience.com]

    “We found that countries without universal policies of BCG vaccination (Italy, Nederland, USA) have been more severely affected compared to countries with universal and long-standing BCG policies,” the study authors explain.

    • by GuB-42 ( 2483988 )

      Interesting.

      Some countries had universal BCG vaccination but stopped doing so at some point. If BCG really has an effect, we should be able to see it on the age distribution. For example if BCG stopped being universal for infants in 1990, there should be a noticeable jump in the number of cases at age 30. It should work in reverse too: if vaccination campaigns started in 1950, there should be a jump at age 70.

  • by Dunbal ( 464142 ) * on Thursday July 02, 2020 @07:59AM (#60253720)
    Someone send these people back to a basic biology course so they can re-learn how an immune system works. Of course some immunity is left. Memory B cells, remember?

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