4 ms·

Have you had the opportunity/availability to get an antibody test? Everyone I've heard with such an anecdote has received multiple negative antibody tests, ane

Have you had the opportunity/availability to get an antibody test? Everyone I've heard with such an anecdote has received multiple negative antibody tests, anecdata! (Only two people I've known)

subsubzero 6y ago
My Brother was in China in November and got pretty sick with back to back to back colds/flu like bugs, I also was very sick for late Nov. - late December, didn't have a fever but had a hard time breathing than normal for a cold/flu, I asked my Doctor and a friend at Stanford and both of them said the antibody tests they have are not accurate. I really want piece of mind if I had covid-19 but am still waiting for a decent antibody test.
- jupp0r 6y ago
  For your situation, existing antibody tests are fine. They are not accurate enough to do mass testing to find out how prevalent SARS2 is in the population. This is because the base rate in the population is pretty low. If you are reasonably sure that you've had it, a false negative/false positive for you is still pretty unlikely (in the 5% order of magnitude range for lateral flow antibody tests, better for ELISA lab tests).
  - gizmo 6y ago
    A positive test result for antibodies is a strong indicator for having been exposed to covid, but a negative test result doesn't say much because 80% of people exposed to covid don't produce antibodies, even if they get sick and recover. It doesn't matter how good the test is if seropositivity is the exception rather than the rule.
    - lbeltrame 6y ago
      > because 80% of people exposed to covid don't produce antibodies Are there any data available to support this claim? That would mean that the virus is cleared by the innate immune system and not the adaptive, but it is still a pretty bold statement. The last I read (a Nature Genetics study, if I recall) was that the antibody quantity was lower in milder cases (but with a large inter-person variability).
      - gizmo 6y ago
        Yes, I linked to a relevant paper in this thread. (And I think it's what you would expect for a disease that is non-symptomatic for many young/healthy people.) > That would mean that the virus is cleared by the innate immune system and not the adaptive Not necessarily, because adaptive antibodies produced through previous exposure to coronaviruses can also bind to covid19.
        lbeltrame 6y ago
        At least the abstract says something different: > Nevertheless, rare but recurring RBD-specific antibodies with potent antiviral activity were found in all individuals tested, suggesting that a vaccine designed to elicit such antibodies could be broadly effective. Very low levels, but still produced. (Note that I still have to dig through the paper.)
        gizmo 6y ago
        My understanding is that those RBD-specific antibodies are not necessarily produced as a response to covid19, but I could be mistaken. In addition: > Plasmas collected an average of 39 days after the onset of symptoms had variable half-maximal neutralizing titers ranging from undetectable in 33% to below 1:1000 in 79% Of course this is only a single study and more research is needed, but I notice people draw way too strong conclusions from studies that show low seropositivity prevalence.
        lbeltrame 6y ago
        It looks like another preprint found antibodies in the airways mucosa instead of blood. That would perhaps explain why some were undetectable.
    - jupp0r 6y ago
      That was exactly my point (and a reason why getting an antibody test is still useful in the context of a single person). Thanks for explaining it better than I did.
- SllX 6y ago
  I’m waiting on these antibody tests as well. My symptoms weren’t as bad as yours but I too had an illness around that time, and so did a fair number of people around me, I remember joking with my drinking buddy that I probably got whatever it was from her. I’m still mostly convinced that whatever it was, it wasn’t COVID-19, but I can’t ignore the sheer number of stories that I keep hearing from people about a strange illness in that time frame. Some medical professionals who I’ve heard on various podcasts addressed these anecdotes and say it probably wasn’t COVID-19, and let’s be fair, it most likely wasn’t. I would still like a way to prove or disprove it though, and same as you, anyone I’ve talked to about it says the antibody tests just aren’t good enough yet to prove anything conclusively. Even the data we do have available sucks. There’s a bunch of States and counties which still aren’t reporting or aren’t reliably reporting recoveries which is artificially inflating the active case count in the United States.
- foobiekr 6y ago
  A bunch of people in my office got sick about two weeks after chinese new year returnees returned to the office. A few people got very, very sick, unlike any kind of flu they'd had before and a bunch of the rest got a sort of dry cough. On a whim, I decided to go get the abbott antibody test to see if it was Covid-19, because it sure seemed like it might have been. But no, negative.
gizmo 6y ago
Recent finding: 80% of people exposed to covid produced only a minimal amount of antibodies. Our immune system protects against millions of diseases, and we don't require specific antibodies for most of them. https://www.biorxiv.org/content/10.1101/2020.05.13.092619v2 https://www.biorxiv.org/content/10.1101/2020.05.13.092619v2
- codezero 6y ago
  Super helpful, thanks, I'll read up some more.
- scotty79 6y ago
  And yet somehow 57% of citizens of Lombardia have covid19 antibodies.
  - lbeltrame 6y ago
    Are you sure about this claim? I live there and I didn't hear such region wide figures, only local city data. In Bergamo it's closer to that from early data, but for example in Milano it might be from 4 to 10 (but in this case the sample was blood donors, so skewed towards younger and healthy).
  - bonzini 6y ago
    No, it's only in the province of Bergamo and there is selection bias because people that chose to take the test presumably has symptoms before. As a counter-anecdote, I know two people from a less hit area, both of whom had fever, and none of them had any antibodies (like, the test said 0.0 for both IgM and IgG).
    - scotty79 6y ago
      True. Just Bergamo. Which changes nothing in my argument. But there's a claim that results were from sufficiently large and random sample: https://www.google.com/amp/s/www.thejakartapost.com/amp/news/2020/06/09/over-half-of-people-tested-in-italys-bergamo-have-covid-19-antibodies.html https://www.google.com/amp/s/www.thejakartapost.com/amp/news... If that's true then my argument still holds. How can 80% not get antibodies if they were detected in 57% of large random sample of some population?

Have you had the opportunity/availability to get an antibody test? Everyone I've heard with such an anecdote has received multiple negative antibody tests, anecdata! (Only two people I've known)

subsubzero 6y ago

My Brother was in China in November and got pretty sick with back to back to back colds/flu like bugs, I also was very sick for late Nov. - late December, didn't have a fever but had a hard time breathing than normal for a cold/flu, I asked my Doctor and a friend at Stanford and both of them said the antibody tests they have are not accurate. I really want piece of mind if I had covid-19 but am still waiting for a decent antibody test.

jupp0r 6y ago
For your situation, existing antibody tests are fine. They are not accurate enough to do mass testing to find out how prevalent SARS2 is in the population. This is because the base rate in the population is pretty low. If you are reasonably sure that you've had it, a false negative/false positive for you is still pretty unlikely (in the 5% order of magnitude range for lateral flow antibody tests, better for ELISA lab tests).
- gizmo 6y ago
  A positive test result for antibodies is a strong indicator for having been exposed to covid, but a negative test result doesn't say much because 80% of people exposed to covid don't produce antibodies, even if they get sick and recover. It doesn't matter how good the test is if seropositivity is the exception rather than the rule.
  - lbeltrame 6y ago
    > because 80% of people exposed to covid don't produce antibodies Are there any data available to support this claim? That would mean that the virus is cleared by the innate immune system and not the adaptive, but it is still a pretty bold statement. The last I read (a Nature Genetics study, if I recall) was that the antibody quantity was lower in milder cases (but with a large inter-person variability).
    - gizmo 6y ago
      Yes, I linked to a relevant paper in this thread. (And I think it's what you would expect for a disease that is non-symptomatic for many young/healthy people.) > That would mean that the virus is cleared by the innate immune system and not the adaptive Not necessarily, because adaptive antibodies produced through previous exposure to coronaviruses can also bind to covid19.
      - lbeltrame 6y ago
        At least the abstract says something different: > Nevertheless, rare but recurring RBD-specific antibodies with potent antiviral activity were found in all individuals tested, suggesting that a vaccine designed to elicit such antibodies could be broadly effective. Very low levels, but still produced. (Note that I still have to dig through the paper.)
        gizmo 6y ago
        My understanding is that those RBD-specific antibodies are not necessarily produced as a response to covid19, but I could be mistaken. In addition: > Plasmas collected an average of 39 days after the onset of symptoms had variable half-maximal neutralizing titers ranging from undetectable in 33% to below 1:1000 in 79% Of course this is only a single study and more research is needed, but I notice people draw way too strong conclusions from studies that show low seropositivity prevalence.
        lbeltrame 6y ago
        It looks like another preprint found antibodies in the airways mucosa instead of blood. That would perhaps explain why some were undetectable.
  - jupp0r 6y ago
    That was exactly my point (and a reason why getting an antibody test is still useful in the context of a single person). Thanks for explaining it better than I did.
SllX 6y ago
I’m waiting on these antibody tests as well. My symptoms weren’t as bad as yours but I too had an illness around that time, and so did a fair number of people around me, I remember joking with my drinking buddy that I probably got whatever it was from her. I’m still mostly convinced that whatever it was, it wasn’t COVID-19, but I can’t ignore the sheer number of stories that I keep hearing from people about a strange illness in that time frame. Some medical professionals who I’ve heard on various podcasts addressed these anecdotes and say it probably wasn’t COVID-19, and let’s be fair, it most likely wasn’t. I would still like a way to prove or disprove it though, and same as you, anyone I’ve talked to about it says the antibody tests just aren’t good enough yet to prove anything conclusively. Even the data we do have available sucks. There’s a bunch of States and counties which still aren’t reporting or aren’t reliably reporting recoveries which is artificially inflating the active case count in the United States.
foobiekr 6y ago
A bunch of people in my office got sick about two weeks after chinese new year returnees returned to the office. A few people got very, very sick, unlike any kind of flu they'd had before and a bunch of the rest got a sort of dry cough. On a whim, I decided to go get the abbott antibody test to see if it was Covid-19, because it sure seemed like it might have been. But no, negative.

gizmo 6y ago

Recent finding: 80% of people exposed to covid produced only a minimal amount of antibodies. Our immune system protects against millions of diseases, and we don't require specific antibodies for most of them. https://www.biorxiv.org/content/10.1101/2020.05.13.092619v2 https://www.biorxiv.org/content/10.1101/2020.05.13.092619v2

codezero 6y ago
Super helpful, thanks, I'll read up some more.
scotty79 6y ago
And yet somehow 57% of citizens of Lombardia have covid19 antibodies.
- lbeltrame 6y ago
  Are you sure about this claim? I live there and I didn't hear such region wide figures, only local city data. In Bergamo it's closer to that from early data, but for example in Milano it might be from 4 to 10 (but in this case the sample was blood donors, so skewed towards younger and healthy).
- bonzini 6y ago
  No, it's only in the province of Bergamo and there is selection bias because people that chose to take the test presumably has symptoms before. As a counter-anecdote, I know two people from a less hit area, both of whom had fever, and none of them had any antibodies (like, the test said 0.0 for both IgM and IgG).
  - scotty79 6y ago
    True. Just Bergamo. Which changes nothing in my argument. But there's a claim that results were from sufficiently large and random sample: https://www.google.com/amp/s/www.thejakartapost.com/amp/news/2020/06/09/over-half-of-people-tested-in-italys-bergamo-have-covid-19-antibodies.html https://www.google.com/amp/s/www.thejakartapost.com/amp/news... If that's true then my argument still holds. How can 80% not get antibodies if they were detected in 57% of large random sample of some population?