9 ms·

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

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.
      - SpicyLemonZest 7y ago
        I'm not sure I follow what you're responding to. Antibodies are definitive proof of a previous infection, which is what I was talking about.
        shakna 7y ago
        > Antibodies are definitive proof of a previous infection, which is what I was talking about. When the studies in question have a high rate of false positives, that is absolutely not the case. It may simply be a statistical anomaly, from taking the incorrect confidence interval. Currently, from the studies taken, it looks like we have high rates of both false negatives, and false positives. Which means that the testing does not give you an accurate picture of whether a population group has previous infections or not.
      - Laforet 7y ago
        I think the argument being made is less about lasting immunity but reevaluating the actual risks for the general population. 8 million people live in NYC and there has been 0.155 million confirmed cases so far. If the actual infection rate is 20% then that represents a 10 fold overestimation of morbidity and mortality. A good place to keep an eye on for the short term would be Sweden. Despite the lack of lockdown their disease penetrance is still on par with the UK.
        shakna 7y ago
        However, biased antibody studies (no self-selection criteria) that may have high rates of both false negatives and false positives do not represent anything about the current level of estimation whatsoever. Which is why when these studies happen, the public is told to wait for it to be assessed, rather than pretending all of us are remotely qualified to judge the content and draw conclusions from it about what actual risks the general population might be facing.
        matwood 7y ago
        > If the actual infection rate is 20% then that represents a 10 fold overestimation of morbidity and mortality. 10 fold over what? A problem since the beginning is that many people are confusing CFR and IFR. Worse is when people compare the IFR of COVID-19 to the CFR of the flu. Regardless, the IFR for COVID-19 has been thought to be .5-1% since the beginning. If we assume the NY antibody study is mostly correct (even with the sampling errors), I believe it puts the IFR in the .5-1% range [1]. If that IFR holds it still means 1.6-3.3M deaths in the US assuming the healthcare does not get overwhelmed. [1] deaths/(cases x 10 fold) x 100 == IFR 21908/(288313 x 10) x 100 == ~.75% Data pulled from https://www.worldometers.info/coronavirus/country/us/ https://www.worldometers.info/coronavirus/country/us/ on 4/26/2020 @ 8am EST.
    - CydeWeys 7y ago
      I totally agree that the confirmed case counts are way too low, because even most people who were symptomatic weren't able to get tested (e.g. me), let alone random people who were asymptomatic. But the 21% study is seriously flawed because it didn't do a random sampling of the population. We need that at a minimum to know with any certainty what the actual exposure rate is. The figures that are coming back from studies using random samples in other places have been much lower.
      - SpicyLemonZest 7y ago
        It did a random sampling. We should do followups to screen off possible biases people have proposed, but stopping random people in the grocery store is by any reasonable standard randomization.
        matwood 7y ago
        No. It’s a random sampling of people who are out during lockdown. It can’t being extrapolated to the whole population when large parts are not leaving their homes.
        SpicyLemonZest 7y ago
        And if you go around to people's homes, you'll oversample people who aren't out during the lockdown. There's no silver bullet here.
        matwood 7y ago
        You do both. This is why study design matters. And it's one of the reasons all of the early antibody studies have issues (the other being test accuracy).
        CydeWeys 7y ago
        It's almost like you need to do your random sample based on a list of all residents, and not just go out and try to find people at various locations.
    - matwood 7y ago
      I don't think anyone is moving goalposts. Most of the antibody studies that have come out have had serious flaws either with the tests themselves or the sampling. The recent NY one was ok, but still had sampling issues because it only sampled people who were out and about during a lockdown. I would expect those people to have a higher prevalence of exposure. With that said, the extrapolated numbers for NY do fall in line with the original IFR of .5-1% The downside is that if that is the IFR then the US is looking at 1.6-3.3M deaths assuming hospital systems can keep up as the infection spreads. Edit. It's also important to talk about infection counts (what antibody tests are looking for) and case counts (people who show symptoms and end up seeking medical care). In the past when people were saying it's just the flu they were comparing COVID-19 IFR to the flus CFR.

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.
    - SpicyLemonZest 7y ago
      I'm not sure I follow what you're responding to. Antibodies are definitive proof of a previous infection, which is what I was talking about.
      - shakna 7y ago
        > Antibodies are definitive proof of a previous infection, which is what I was talking about. When the studies in question have a high rate of false positives, that is absolutely not the case. It may simply be a statistical anomaly, from taking the incorrect confidence interval. Currently, from the studies taken, it looks like we have high rates of both false negatives, and false positives. Which means that the testing does not give you an accurate picture of whether a population group has previous infections or not.
    - Laforet 7y ago
      I think the argument being made is less about lasting immunity but reevaluating the actual risks for the general population. 8 million people live in NYC and there has been 0.155 million confirmed cases so far. If the actual infection rate is 20% then that represents a 10 fold overestimation of morbidity and mortality. A good place to keep an eye on for the short term would be Sweden. Despite the lack of lockdown their disease penetrance is still on par with the UK.
      - shakna 7y ago
        However, biased antibody studies (no self-selection criteria) that may have high rates of both false negatives and false positives do not represent anything about the current level of estimation whatsoever. Which is why when these studies happen, the public is told to wait for it to be assessed, rather than pretending all of us are remotely qualified to judge the content and draw conclusions from it about what actual risks the general population might be facing.
      - matwood 7y ago
        > If the actual infection rate is 20% then that represents a 10 fold overestimation of morbidity and mortality. 10 fold over what? A problem since the beginning is that many people are confusing CFR and IFR. Worse is when people compare the IFR of COVID-19 to the CFR of the flu. Regardless, the IFR for COVID-19 has been thought to be .5-1% since the beginning. If we assume the NY antibody study is mostly correct (even with the sampling errors), I believe it puts the IFR in the .5-1% range [1]. If that IFR holds it still means 1.6-3.3M deaths in the US assuming the healthcare does not get overwhelmed. [1] deaths/(cases x 10 fold) x 100 == IFR 21908/(288313 x 10) x 100 == ~.75% Data pulled from https://www.worldometers.info/coronavirus/country/us/ https://www.worldometers.info/coronavirus/country/us/ on 4/26/2020 @ 8am EST.
  - CydeWeys 7y ago
    I totally agree that the confirmed case counts are way too low, because even most people who were symptomatic weren't able to get tested (e.g. me), let alone random people who were asymptomatic. But the 21% study is seriously flawed because it didn't do a random sampling of the population. We need that at a minimum to know with any certainty what the actual exposure rate is. The figures that are coming back from studies using random samples in other places have been much lower.
    - SpicyLemonZest 7y ago
      It did a random sampling. We should do followups to screen off possible biases people have proposed, but stopping random people in the grocery store is by any reasonable standard randomization.
      - matwood 7y ago
        No. It’s a random sampling of people who are out during lockdown. It can’t being extrapolated to the whole population when large parts are not leaving their homes.
        SpicyLemonZest 7y ago
        And if you go around to people's homes, you'll oversample people who aren't out during the lockdown. There's no silver bullet here.
        matwood 7y ago
        You do both. This is why study design matters. And it's one of the reasons all of the early antibody studies have issues (the other being test accuracy).
        CydeWeys 7y ago
        It's almost like you need to do your random sample based on a list of all residents, and not just go out and try to find people at various locations.
  - matwood 7y ago
    I don't think anyone is moving goalposts. Most of the antibody studies that have come out have had serious flaws either with the tests themselves or the sampling. The recent NY one was ok, but still had sampling issues because it only sampled people who were out and about during a lockdown. I would expect those people to have a higher prevalence of exposure. With that said, the extrapolated numbers for NY do fall in line with the original IFR of .5-1% The downside is that if that is the IFR then the US is looking at 1.6-3.3M deaths assuming hospital systems can keep up as the infection spreads. Edit. It's also important to talk about infection counts (what antibody tests are looking for) and case counts (people who show symptoms and end up seeking medical care). In the past when people were saying it's just the flu they were comparing COVID-19 IFR to the flus CFR.