8 ms·

Did you see the NYC antibody sample that showed that approximately 21 percent of citizens had antibodies? It seems like a nursing home is a pretty bad represen

by JPKab 7y ago

Did you see the NYC antibody sample that showed that approximately 21 percent of citizens had antibodies? It seems like a nursing home is a pretty bad representation of a population.

ilamont 7y ago
I agree, but so is a group of male inmates (many of them older) compared to the general population. Until more testing on this group is done in a few weeks and symptoms emerge, we won’t have a clear picture on how many are truly asymptomatic.
prussian 7y ago
Am I the only one who is still confused by what they're finding in these antibody tests? Are they looking for antibodies that attach to specific features unique to SARS-CoV-2? Because I'm pretty sure even HCoV-NL63 enter lung cells through ACE2 as well. How can they tell antibodies for these viruses apart? Also aren't antibodies effectively developed in a sort of random process?
- SN76477 7y ago
  I am confused as can be about all of it now. First it was stay locked in, then heard immunity, now they say heard immunity may not happen.
  - 13415 7y ago
    If you're confused by this, you may need to check your news sources. Experts have been explaining all of this for months. First, people need to stay locked in and keep distance in order to slow down the spreading so health care systems don't get overwhelmed. Second, the disease itself can only be stopped once herd immunity is reached. Ideally, herd immunity is achieved by vaccination, once there is one. Until then, social distancing is needed to limit the number of deaths and keep the health system working. Third, it is not yet clear whether long-lasting immunity can be achieved at all. It's very likely, but there is not yet enough data. Immunity may last from 2 months to 2 years or longer. We don't know yet for sure.
    - arcticbull 7y ago
      Not sure why you're being downvoted, this is well established. Even with everyone indoors, the US new infection rate remains around 40,000 new cases per day recorded -- and holding steady. Now with states re-opening that can only go one direction, until herd immunity is established.
      - IAmGraydon 7y ago
        Those are positive tests. They are remaining high because the number of tests has been increasing. The important metric to track is percent positive tests, which has been consistently dropping for weeks. https://coronavirus.1point3acres.com/en/test https://coronavirus.1point3acres.com/en/test
        arcticbull 7y ago
        I'm curious if that's true -- based on that excellent data, it appears that the number of people who test positive has been pretty much steady. Chances are those were always, and remain, positive tests at the point of care/admission to a hospital. The new tests are likely randos. So long as we continue to see the same raw absolute number of positive tests, I'd say it's not a win -- yet. There's been in fact a steady increase since 4/21 in positive tests in real number terms.
      - zaroth 7y ago
        The 40,000 new cases per day is predominantly a function of the number of tests being run. The number of actual infections has far outpaced the number of tests. Look at test positivity rate across NYC for example. https://www1.nyc.gov/assets/doh/downloads/pdf/imm/covid-19-data-map-04252020-1.pdf https://www1.nyc.gov/assets/doh/downloads/pdf/imm/covid-19-d... If instead we had done random sampling we could have been very accurately projecting the number of active cases pretty easily, but apparently we’ve mostly decided not to do that until now with the antibody studies.
      - jacquesm 7y ago
        And that's assuming that herd immunity will be established, which we have no way of knowing until we know how long - and if - a person is immune after recovery.
  - dnautics 7y ago
    you're not wrong to be. I think the problem is that there's this perception that you must be authoritative to get people to do things, and also this perception that science is authoritative. As a former scientist I think both are wrong, and especially science under duress is likely to be even wronger, for many reasons. We don't live in star trek where you can boop boop a console and magically get answers. I wish we had leaders that had the chutzpah to say things like, "look the science is inconclusive, so we won't arrest you, but please do the right thing and wear masks". But we don't. And also we have people spouting completely non-evidence based assertions like "if you don't force people to wear masks, then they won't". Which of course fuels assholes to flaunt not wearing masks, because now it's not about doing the right thing, it's about freedom.
- sndean 7y ago
  > Are they looking for antibodies that attach to specific features unique to SARS-CoV-2? They're all slightly different, but yes they're looking for antibodies against specific parts of SARS-CoV-2, like the N protein [0][1]. I think the N protein ones are most common. I just did a BLASTp against SARS-CoV's N protein and there's maybe ~90% homology? So I would hope they're using a site that's different between the two. Or, there's an assumption that most people have not been previously exposed to SARS-CoV or others with similar N proteins. > Also aren't antibodies effectively developed in a sort of random process? Yeah, but there's only so many prominent features to a virus that you can make antibodies against. [0] https://www.abcam.com/novel-coronavirus-igg-antibody-detection-kit-sars-cov-2-ab272243.html https://www.abcam.com/novel-coronavirus-igg-antibody-detecti... [1] https://www.ncbi.nlm.nih.gov/protein/QHW06046.1?report=fasta https://www.ncbi.nlm.nih.gov/protein/QHW06046.1?report=fasta
- lend000 7y ago
  I am also curious about this. As I understand it, an immune individual could have any mathematical subset of antibodies from the base set, which is the collection of all proteins that can bind to something on the surface of a COVID-19 virion. Furthermore, I would think these base sets can change slightly for different mutations of the virus. Perhaps humans tend to have enough random antibody generation that they are likely to start mass producing most of the protein shapes that are able to bind to the virus? And as another commenter pointed out, there are not that many options to bind to.
  - vikramkr 7y ago
    Look up VDJ recombination[0] for a sense of how antibodies are generated. Ling story short, yeah its pretty random in a really clever process that generates enormous variability. There are also only so many features to bind on the covid virus protein, which are what we test, but there are a lot of antibodies that our body can make against them
jpster 7y ago
I am not sure how reliable these studies are, given this reporting: https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html https://www.nytimes.com/2020/04/24/health/coronavirus-antibo...
bashtoni 7y ago
It didn't show that - there's a good analysis at https://towardsdatascience.com/were-21-of-new-york-city-residents-really-infected-with-covid-19-aab6ebefda0 https://towardsdatascience.com/were-21-of-new-york-city-resi...
pbourke 7y ago
I don’t buy any inference drawn from that study that is in the realm of “20% of the population of NYC was exposed to SARS-CoV-2 and developed immunity” I think that will be the primary message that people will get from that study.
- SpicyLemonZest 7y ago
  Is there any evidence that would convince you 20% of NYC was exposed and developed immunity?
  - CydeWeys 7y ago
    How about an actually randomly sampled test, for starters?
    - SpicyLemonZest 7y ago
      It's the "for starters" that concerns me. A lot of us were always saying that official case counts are much too low, and antibody surveys were supposed to be the definitive proof that we were responsibly waiting for. Now they're starting to come out, and still nobody believes it. I worry it's a moving goalpost, and no evidence will ever be enough to make people start reconsidering their beliefs.
      - shakna 7y ago
        > antibody surveys were supposed to be the definitive proof that we were responsibly waiting for. Simple question: Why? For most coronaviruses, antibodies reflect only a temporary immunity, that is usual gone in 6-24 months, due to the nature of these viruses. All an antibody survey shows is that antibodies can be created, not that they are effective long term. Showing a longer term immunity takes statistical analysis, usually after that temporary window has ended. In fact, antibody surveys may not even show an effective temporary immunity, if the wrong kinds of antibodies are being screened for. Knowing this, why was the antibody surveys supposed to be some golden bullet? The advice from the medical community was "this is being actively studied, wait and see." The surveys provide the medical community with important data, but they don't really provide us with policy making data, and they certainly don't predict the future for the general population when exposed to the virus.
ta1771 7y ago
Antibodies for which of the 8+ strains?
AJ007 7y ago
8,399,000 people in NYC, 21 percent of that is 1,763,790. 1% of that is 17,000. So far as of Saturday at 6:49pm EST 16,919 have officially died in NYC. I think the anti-body test in this case is fairly close and the death rate is probably 1% more or less depending on the demographic distribution. Obviously there are a number of people in NYC who will die over the next month even if all new infections where halted right now. The serology tests are just wrong when only a small number of people in the sample were infected, which is what we’ve seen from the stuff in CA so far.
- CydeWeys 7y ago
  You're using the death count for the entire state, not just NYC. The blood antibody test positive % for the overall state is 13, not 21. And the population is around 19.5 million.
  - briandear 7y ago
    People are going to use whatever version of the facts supports their bias.
  - cozzyd 7y ago
    The NYC DPH reports both a confirmed and probable death count. The sum of those, as of Saturday, is 16270
hristov 7y ago
I am not sure that these antibody tests mean what people generally think they mean. For example, there seem to be multiple events where people get sick even after it has been established that they have antibodies. Furthermore, people in environments with a lot of virus (i.e., cruise ships, hospitals, or just northern italian towns where the virus has run amok, tend to get sick and die at much higher rate than those antibody tests would suggest. There may be a mechanism for multiple infection which makes multiple exposure more dangerous even if you have antibodies.
- FiberBundle 7y ago
  >For example, there seem to be multiple events where people get sick even after it has been established that they have antibodies. Do you have a source for that?

by JPKab 7y ago

Did you see the NYC antibody sample that showed that approximately 21 percent of citizens had antibodies? It seems like a nursing home is a pretty bad representation of a population.

ilamont 7y ago

I agree, but so is a group of male inmates (many of them older) compared to the general population. Until more testing on this group is done in a few weeks and symptoms emerge, we won’t have a clear picture on how many are truly asymptomatic.

prussian 7y ago

Am I the only one who is still confused by what they're finding in these antibody tests? Are they looking for antibodies that attach to specific features unique to SARS-CoV-2? Because I'm pretty sure even HCoV-NL63 enter lung cells through ACE2 as well. How can they tell antibodies for these viruses apart? Also aren't antibodies effectively developed in a sort of random process?

SN76477 7y ago
I am confused as can be about all of it now. First it was stay locked in, then heard immunity, now they say heard immunity may not happen.
- 13415 7y ago
  If you're confused by this, you may need to check your news sources. Experts have been explaining all of this for months. First, people need to stay locked in and keep distance in order to slow down the spreading so health care systems don't get overwhelmed. Second, the disease itself can only be stopped once herd immunity is reached. Ideally, herd immunity is achieved by vaccination, once there is one. Until then, social distancing is needed to limit the number of deaths and keep the health system working. Third, it is not yet clear whether long-lasting immunity can be achieved at all. It's very likely, but there is not yet enough data. Immunity may last from 2 months to 2 years or longer. We don't know yet for sure.
  - arcticbull 7y ago
    Not sure why you're being downvoted, this is well established. Even with everyone indoors, the US new infection rate remains around 40,000 new cases per day recorded -- and holding steady. Now with states re-opening that can only go one direction, until herd immunity is established.
    - IAmGraydon 7y ago
      Those are positive tests. They are remaining high because the number of tests has been increasing. The important metric to track is percent positive tests, which has been consistently dropping for weeks. https://coronavirus.1point3acres.com/en/test https://coronavirus.1point3acres.com/en/test
      - arcticbull 7y ago
        I'm curious if that's true -- based on that excellent data, it appears that the number of people who test positive has been pretty much steady. Chances are those were always, and remain, positive tests at the point of care/admission to a hospital. The new tests are likely randos. So long as we continue to see the same raw absolute number of positive tests, I'd say it's not a win -- yet. There's been in fact a steady increase since 4/21 in positive tests in real number terms.
    - zaroth 7y ago
      The 40,000 new cases per day is predominantly a function of the number of tests being run. The number of actual infections has far outpaced the number of tests. Look at test positivity rate across NYC for example. https://www1.nyc.gov/assets/doh/downloads/pdf/imm/covid-19-data-map-04252020-1.pdf https://www1.nyc.gov/assets/doh/downloads/pdf/imm/covid-19-d... If instead we had done random sampling we could have been very accurately projecting the number of active cases pretty easily, but apparently we’ve mostly decided not to do that until now with the antibody studies.
    - jacquesm 7y ago
      And that's assuming that herd immunity will be established, which we have no way of knowing until we know how long - and if - a person is immune after recovery.
- dnautics 7y ago
  you're not wrong to be. I think the problem is that there's this perception that you must be authoritative to get people to do things, and also this perception that science is authoritative. As a former scientist I think both are wrong, and especially science under duress is likely to be even wronger, for many reasons. We don't live in star trek where you can boop boop a console and magically get answers. I wish we had leaders that had the chutzpah to say things like, "look the science is inconclusive, so we won't arrest you, but please do the right thing and wear masks". But we don't. And also we have people spouting completely non-evidence based assertions like "if you don't force people to wear masks, then they won't". Which of course fuels assholes to flaunt not wearing masks, because now it's not about doing the right thing, it's about freedom.
sndean 7y ago
> Are they looking for antibodies that attach to specific features unique to SARS-CoV-2? They're all slightly different, but yes they're looking for antibodies against specific parts of SARS-CoV-2, like the N protein [0][1]. I think the N protein ones are most common. I just did a BLASTp against SARS-CoV's N protein and there's maybe ~90% homology? So I would hope they're using a site that's different between the two. Or, there's an assumption that most people have not been previously exposed to SARS-CoV or others with similar N proteins. > Also aren't antibodies effectively developed in a sort of random process? Yeah, but there's only so many prominent features to a virus that you can make antibodies against. [0] https://www.abcam.com/novel-coronavirus-igg-antibody-detection-kit-sars-cov-2-ab272243.html https://www.abcam.com/novel-coronavirus-igg-antibody-detecti... [1] https://www.ncbi.nlm.nih.gov/protein/QHW06046.1?report=fasta https://www.ncbi.nlm.nih.gov/protein/QHW06046.1?report=fasta
lend000 7y ago
I am also curious about this. As I understand it, an immune individual could have any mathematical subset of antibodies from the base set, which is the collection of all proteins that can bind to something on the surface of a COVID-19 virion. Furthermore, I would think these base sets can change slightly for different mutations of the virus. Perhaps humans tend to have enough random antibody generation that they are likely to start mass producing most of the protein shapes that are able to bind to the virus? And as another commenter pointed out, there are not that many options to bind to.
- vikramkr 7y ago
  Look up VDJ recombination[0] for a sense of how antibodies are generated. Ling story short, yeah its pretty random in a really clever process that generates enormous variability. There are also only so many features to bind on the covid virus protein, which are what we test, but there are a lot of antibodies that our body can make against them

jpster 7y ago

I am not sure how reliable these studies are, given this reporting: https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html https://www.nytimes.com/2020/04/24/health/coronavirus-antibo...

bashtoni 7y ago

It didn't show that - there's a good analysis at https://towardsdatascience.com/were-21-of-new-york-city-residents-really-infected-with-covid-19-aab6ebefda0 https://towardsdatascience.com/were-21-of-new-york-city-resi...

pbourke 7y ago

I don’t buy any inference drawn from that study that is in the realm of “20% of the population of NYC was exposed to SARS-CoV-2 and developed immunity” I think that will be the primary message that people will get from that study.

SpicyLemonZest 7y ago
Is there any evidence that would convince you 20% of NYC was exposed and developed immunity?
- CydeWeys 7y ago
  How about an actually randomly sampled test, for starters?
  - SpicyLemonZest 7y ago
    It's the "for starters" that concerns me. A lot of us were always saying that official case counts are much too low, and antibody surveys were supposed to be the definitive proof that we were responsibly waiting for. Now they're starting to come out, and still nobody believes it. I worry it's a moving goalpost, and no evidence will ever be enough to make people start reconsidering their beliefs.
    - shakna 7y ago
      > antibody surveys were supposed to be the definitive proof that we were responsibly waiting for. Simple question: Why? For most coronaviruses, antibodies reflect only a temporary immunity, that is usual gone in 6-24 months, due to the nature of these viruses. All an antibody survey shows is that antibodies can be created, not that they are effective long term. Showing a longer term immunity takes statistical analysis, usually after that temporary window has ended. In fact, antibody surveys may not even show an effective temporary immunity, if the wrong kinds of antibodies are being screened for. Knowing this, why was the antibody surveys supposed to be some golden bullet? The advice from the medical community was "this is being actively studied, wait and see." The surveys provide the medical community with important data, but they don't really provide us with policy making data, and they certainly don't predict the future for the general population when exposed to the virus.

ta1771 7y ago

Antibodies for which of the 8+ strains?

AJ007 7y ago

8,399,000 people in NYC, 21 percent of that is 1,763,790. 1% of that is 17,000. So far as of Saturday at 6:49pm EST 16,919 have officially died in NYC. I think the anti-body test in this case is fairly close and the death rate is probably 1% more or less depending on the demographic distribution. Obviously there are a number of people in NYC who will die over the next month even if all new infections where halted right now. The serology tests are just wrong when only a small number of people in the sample were infected, which is what we’ve seen from the stuff in CA so far.

CydeWeys 7y ago
You're using the death count for the entire state, not just NYC. The blood antibody test positive % for the overall state is 13, not 21. And the population is around 19.5 million.
- briandear 7y ago
  People are going to use whatever version of the facts supports their bias.
- cozzyd 7y ago
  The NYC DPH reports both a confirmed and probable death count. The sum of those, as of Saturday, is 16270

hristov 7y ago

I am not sure that these antibody tests mean what people generally think they mean. For example, there seem to be multiple events where people get sick even after it has been established that they have antibodies. Furthermore, people in environments with a lot of virus (i.e., cruise ships, hospitals, or just northern italian towns where the virus has run amok, tend to get sick and die at much higher rate than those antibody tests would suggest. There may be a mechanism for multiple infection which makes multiple exposure more dangerous even if you have antibodies.

FiberBundle 7y ago
>For example, there seem to be multiple events where people get sick even after it has been established that they have antibodies. Do you have a source for that?