17 ms·

Some more information about the study here: https://pressroom.usc.edu/what-a-usc-la-county-antibody-study-can-teach-us-about-covid-19/ https://pressroom.usc.edu

Some more information about the study here: https://pressroom.usc.edu/what-a-usc-la-county-antibody-study-can-teach-us-about-covid-19/ https://pressroom.usc.edu/what-a-usc-la-county-antibody-stud... Population is supposed to be representative of LA county. Tests are from Premier Biotech with some preliminary data on false negative/ false positive rates shown. I suspect assumptions related to the test itself, rather than population, may be a bigger factor for any inaccuracies. There's also the question of whether antibody response implies immunity for SARS-COV2 Another interesting aspect of the result was 6% of men showed antibodies but only 2% of women tested. Also: --2.4% of people between the ages of 18 and 34 had antibodies to the coronavirus --5.6% of people between 35 and 54 had antibodies --4.3% of between 55 and older had antibodies Edit: The key assumption that really, really needs to be triply checked here is the specificity of the test. They're assuming 99.5%, similar to the Stanford study I believe. If it's closer to 98% then prevalence estimate confidence intervals should include 0%, I believe. Also should be noted that the same PI on the Stanford study, Jay Bhattacharya, is also involved in this. Same criticisms likely apply here - more caution needed! Second edit: On further reflection, I think these studies could do serious damage based on how the results are being announced by press-release - in this case, afaik there's no pre-print. In our current environment this isn't just science. Policy is being enacted and people may die because of poorly framing results. Everyone involved needs to take a step back and think through this carefully. Also - did anyone figure out why a hedge fund guy was an author on the Stanford pre-print? And why that same guy then published a Wall Street Journal op-ed about the study without identifying himself as a co-author? Shady stuff.

tempsy 6y ago
I’m very skeptical. Why were they so few hospitalizations in LA vs NYC if such a large % in LA contracted Covid? Is this suggesting that a much, much higher % in NYC have it (and the number of those with any serious symptom and thus need for hospitalization was higher)?
- teilo 6y ago
  Yes, that is the implication. And if this is the case, that is very good news.
- SpicyLemonZest 6y ago
  Yes. The consensus I've seen forming is that at least 15% of NYC has had it by now - a variety of questionably random samples have suggested numbers near that.
  - tempsy 6y ago
    NY has 17x more deaths than California. That would mean if 3% of CA was infected (yes this is LA only but for ease of comparison) it would be 51%+ of NY was infected. Far more than just 15%.
    - arcticbull 6y ago
      CFR is not a great way of comparing across regions, it could be due to any number of factors. Demographics (i.e. age), co-moribidities and the amount of hospital space available.
      - arcticbull 6y ago
        In fact the per-country spread of CFR is huge, from a low of 0.07% in Singapore to a high of 14.93% in Belgium, a whole 3 orders of magnitude. The H1N1 influenza CFR at a similar point in the outbreak was between 0.1% and 5.1% -- but the final IFR ended up at 0.02% [1]. [1] https://www.cebm.net/covid-19/global-covid-19-case-fatality-rates/ https://www.cebm.net/covid-19/global-covid-19-case-fatality-...
    - SpicyLemonZest 6y ago
      The comparison is overweighting LA county, which has 25% of California's population but 60% of its deaths. (I don't know what the math ends up being off the top of my head.)
    - BlackJack 6y ago
      LA is one of the densest parts of CA though, outside of SF/Bay Area. So if LA is 3%, you could assume the state as a whole is maybe 1-2%. Then 17x that becomes 17-34%, which seems more reasonable.
  - 6y ago
- CydeWeys 6y ago
  It's for sure true that a huge number of people in NYC got it, way surpassing the confirmed cases count. The state is currently doing a serology study here and results should be published next week.
  - tempsy 6y ago
    Sure I believe NYC has way higher prevalence of cases but difference in deaths would imply majority of population was infected and they’d essentially be at herd immunity now. It’s not implausible but find it hard to believe.
    - CydeWeys 6y ago
      We'll know soon enough. The blood serology randomized trial is underway. I suspect some neighborhoods might be at 50%, but the city overall won't be.
  - artursapek 6y ago
    Maybe they'll finally end this ridiculous lockdown when that one is released
- strangeloops85 6y ago
  I think NYC almost certainly has much large prevalence than LA given hospitalization data alone. One factor could be the nature of transmission. Regions where transmission occurs with high viral loads entering at the point of infection (for example, hospital-acquired infections) could see more severe disease progression. You would therefore expect a high hospitalization rate relative to prevalence. It's possible in other regions, including CA, hospitalization rate as a function of prevalence is lower because acquisition is largely at lower viral loads resulting in less rapid and severe disease progression. This is, of course, a hypothesis and very likely not correct. Time will tell. Other important factors include age distribution of infection, as well as weather conditions and prevalence of pre-existing conditions.
  - tempsy 6y ago
    Yes agree NYC will have much higher prevalence but it has 17x the deaths - if fatality rate is similar then it would be like 50%+ of New Yorkers have contracted Covid. Just a little hard to believe.
    - hilbertseries 6y ago
      5.6m people ride the New York subway everyday.
      - tempsy 6y ago
        There’s a decreasing number of positive test cases each day in NYC too though. At highest point was 50% and now under 30% or so. I’m not sure if those tested get the antibody test as well but it implies a larger percentage of symptomatic people are testing negative in nyc.
        asdf21 6y ago
        Almost no one gets an antibody test yet, unless it's some special controlled study.
      - catlas3r 6y ago
- arcticbull 6y ago
  In part because all the headline numbers we've seen are CFR numbers which suffer from huge adverse selection bias -- and aren't directly comparable between regions for a lot of reasons. As I've mentioned before, using CFR to determine fatality rate of the disease is like trying to determine the fatality rate of skydiving by measuring the ratio of people who go to hospital with skydiving injuries over those who recover. Obviously you'd think skydiving kills basically everyone who does it, but it just doesn't. It's starting to become clear that the infection fatality rate of COVID is in the lower quartile of the range 0.25-1%. And yeah, a huge portion of New York likely has it. It's super contagious.
  - aero142 6y ago
    Define "huge portion" because will still have to square this with the negative test data from NYC.
    - joe_the_user 6y ago
      Yeah, trying to do the basic math on the implications of these figures...[Not claiming they're true, that's a different question] The article says 221,000 infected at a 2.8% rate, in "early April". So they're assuming a 7,892,857 population. Currently, we have 601 Deaths total in LA[1], which we can assume are a result of early april event on April 20. So a 0.002% "fatality rate" relative to total exposures, "Woohoo" (NOTE, this is an optimistic figure implied by this study, the standard 2% [edited] previously claim but still not equivalent to the flu, which has 0.2% [edited] relative people who get sick). Now, with weekly doubling: 221,0008 = 1,768,000 infection now = 22.4% - > 4808 deaths. However, past 10%, we can ask whether we start reaching saturation/diminishing returns. But that is a key question. -- Let's look at NYC. There we have 14,500 Death. Using the article's implied figure, 14,500/ 0.002 = 7,250,000 infected on April 1, out of 8,398,748. So this implies an infection rate of 7,250,000/8,398,748 = 86.32239%, which, in fact, seems very implausible and which implies; a higher death rate among "vulnerable people". Maybe we're about to hit full saturation with NYC and see an immediate decline. Now, the other bad* scenario is the possibility that a lot of sickness and death NOW is being driven by reinfection, that exposure isn't giving much immunity at all and instead of the unexposed dying, what we're seeing is the re-exposed dying and with this dynamic, the death rate settle into a steady and unacceptably high level. Note that Italy, which has seen a high death rate, hasn't a strong drop-off at all, just gradual plateauing. IE, guess what, one possibility is "herd immunity" just doesn't exist for this virus. Anyway, time will tell, literally a week will tell if NYC has enough fatalities to make this 0.002 exposure-to-death rate numerically impossible. [1] covid-19.live Edit: corrected conversion ratio to percentages.
- CPLX 6y ago
  I think the obvious conclusion (just in logical progression if you take this premise as true) is that the percentage of NYC residents who contracted it was much higher than previously assumed.
  - tempsy 6y ago
    Yes but the difference in fatalities is so large that it would imply majority of New Yorkers were infected and the city has achieved herd immunity. It’s not implausible just find it hard to believe.
    - CPLX 6y ago
      It's hard to believe, I would think, because it would be such a remarkably positive development. But just from a logical perspective it follows clearly from this data, and there's nothing fundamental about the situation that makes it particularly unlikely. Of course it's quite possible that the LA data isn't really applicable for any number of reasons. But the idea that COVID will run through dense populations mercilessly, but quickly, and then sort of peter out is completely within the range of possible and non-shocking outcomes. It's the natural outcome of an extremely communicable disease with a large prevalence of asymptomatic transmission and there's plenty of corroborating evidence for the idea that this is one of those. It's also quite likely that the false-positive rate with this test is super high. Who knows.
    - vanniv 6y ago
      If 50% of NYC has had the virus, they won't have herd immunity yet -- of these studies are correct, then the virus is horrendously infectious -- making 90%+ of population required for immunity.
- JPKab 6y ago
  It needs to be emphasized here: This virus is much more transmissible than the viruses we usually deal with in humans. If a virus has a low fatality rate, but is extremely contagious and prevalent, hospitals will get overwhelmed. A small percentage of a big enough number is itself a big number. The subway and high-utilization of buses are likely factors in NYC vs. LA. LA is much more representative of the typical US city. Frankly, I'm not sure why so many on HN are surprised by this. The scientific data on asymptomatic carriers coming out of Italy, Germany, South Korea, and Iceland has been very clear on a majority asymptomatic frame for this virus. I think that maybe authorities and responsible people are concerned that this information could lead to people flouting lockdowns more.
  - arcticbull 6y ago
    Even the Diamond Princess showed a 50+% asymptomatic rate and that group skewed way, way older than average -- you know, people who take cruises.
    - acqq 6y ago
      50? Just initially, but in a week or two more of these developed symptoms, so more recent number was just 18%: https://www.cebm.net/covid-19/covid-19-what-proportion-are-asymptomatic/ https://www.cebm.net/covid-19/covid-19-what-proportion-are-a... "Setting: Diamond Princess cruise ship, Yokohama, Japan (n=-634 tested positive). Proportion: 18%" Also: "23 Residents of a Long-Term Care Nursing Facility King County, Washington 10 (43%) had symptoms, and 13 (57%) were asymptomatic." But then: "Seven days after testing, 10 of 13 asymptomatics developed symptoms" That means that just 3 of 23 remained asymptomatic there too, i.e. 13%. It is estimated that the people mostly spread this virus exactly in the phase where they still haven't developed symptoms, and the virus can be detected. But that doesn't mean they will remain without the symptoms.
      - asdf21 6y ago
        I suspect most people notice a bit of a cold or "allergies" Like you said, probably only 10% to 15% truly asymptomatic.
- jjtheblunt 6y ago
  Might NYC have more vulnerable people, or more confined spaces for spreading (elevators in high rises, e.g.) ?
- smsm42 6y ago
  https://www.worldometers.info/coronavirus/country/us/ https://www.worldometers.info/coronavirus/country/us/ right now shows 12850 cases per 1M in NY, which is 1.2%. Which is pretty close to what the study shows for LA. So it's not actually suggesting NY has much more than it's already known, if we assumed overall percentage would be similar for both. It does suggest California - which currently lists 853/mln - undercounts it by more than 10x. Of course, provided that the study is true. Also, having antibodies and being hospitalized is a very different thing. If a lot of the cases are asymptomatic or very light you won't see hospitalizations and you'd never know the person had an encounter with the particular virus until you do mass testing. And NY is quite different from LA, as far as I know, in terms of how dense population can be and how much people use mass-transportation and other high-risk scenarios, and the probability of being hospitalized may also depend on that (in other words, it may matter not only whether you had any contact with the virus, but in which circumstances and how much of the contact you had). That doesn't prove the study is true of course, but I don't see anything from comparison with NY that makes it implausible on its face.
- emmelaich 6y ago
  LA is far less dense, fewer travel by public transport, and the weather is much warmer. The people are probably healthier too.
- pengaru 6y ago
  Just speculating here but I hung out with some NYC folks last month in SoCal and they practically all smoked. It was very strange, I rarely encounter smokers living in California.
  - catlas3r 6y ago
    Cigarette smoking rate is widely studied; no reason to use anecdotal data here. The tobacco smoking rate in New York is 14.1%; it's 11.3% in California. Some difference, yes, but far less difference than you see between either and some rural southern states where the numbers can be roughly double that. https://www.cdc.gov/statesystem/cigaretteuseadult.html https://www.cdc.gov/statesystem/cigaretteuseadult.html
- closeparen 6y ago
  Case fatality rate is # of deaths / # of positive tests. It’s enormously biased by the availability of testing, and the allocation of the tests we have to the sickest people. It’s not especially likely to generalize to the population at large. We need large scale random sampling of the population for that. Everyone is eager for these results, because there’s a good chance that the true case count is higher by anywhere from 2x to 100x. If it is, then proportionally fewer people are expected to die as the virus eventually does churn through the whole population. It’s probably still too early to tell, but this is promising.
- DeonPenny 6y ago
  No the very obvious conclusion is that covid-19 isn't very deadly. Thats what every test has concluded. Its that the death rate is closer to .3% than the 3% that the WHO quoted and much closer to the flu's death rate of .1%
elihu 6y ago
> Another interesting aspect of the result was 6% of men showed antibodies but only 2% of women tested. That is interesting. So far, men are more likely to die of covid-19 (almost a 2:1 ratio) than women; if this is a repeatable result it would seem to suggest that the reason is that fewer women are becoming infected, not that women are somehow less likely to exhibit extreme symptoms when infected.
- guscost 6y ago
  Or that women are less likely to need antibodies to clear this infection. Not everyone develops antibodies for every disease, the immune system is super complicated.
herf 6y ago
Premier is an importer for "Hangzhou Biotest Biotech Co". Most of the validation data in the Stanford preprint also appear in this sell sheet: http://img.bj.wezhan.cn/content/sitefiles/2005911/images/13248611_IMG_9396-20200328-102944.jpeg http://img.bj.wezhan.cn/content/sitefiles/2005911/images/132... Stanford reports doing a 30-person validation test with pre-COVID-19 hip surgery patients (100% negative). But this is not enough to validate these population-scale tests, especially when 98.5% specificity (rather than 99.5%) would fully invalidate the headline result.
- zby 6y ago
  > Stanford reports doing a 30-person validation test with pre-COVID-19 hip surgery patients (100% negative) Hmm - I guess I should now go to the source - but from the other link: " test validation included a total of 30+371 pre-covid blood tests, and only 399 of them came back negative." https://statmodeling.stat.columbia.edu/2020/04/19/fatal-flaws-in-stanford-study-of-coronavirus-prevalence/ https://statmodeling.stat.columbia.edu/2020/04/19/fatal-flaw... - I think I trust it more
  - herf 6y ago
    Yes, the 371 are listed on the sell sheet (see tweet above). Unclear if Stanford was involved, but I would suspect not.
goalieca 6y ago
Our initial policy was based on early data from China which seemed to imply 3% mortality, an R0 of 2.4 and a 5% hospitalization rate. In the past month, data from all sources and methods is showing this to be far less deadly but also far more contagious. Perhaps it’s time to adjust our view of the lockdown.
- usaar333 6y ago
  Well, R0 is probably still about 2.4 in most cities in the United States (NYC, like Wuhan, considerably higher). Source suggesting this: https://www.medrxiv.org/content/10.1101/2020.04.12.20062943v1.full.pdf https://www.medrxiv.org/content/10.1101/2020.04.12.20062943v... I think it has been pretty obvious that IFR is not 3% for a long time. Imperial College had dropped it to 0.67% in China 3 weeks ago (https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30243-7/fulltext https://www.thelancet.com/journals/laninf/article/PIIS1473-3...)
- Jeema101 6y ago
  I think the view that the infection fatality rate is significantly lower than the case fatality rate has already been factored into public policy. Because even if the IFR is around 0.5% then that still works out to > 1,000,000 people dead in the US in an uncontrolled spread scenario. It would have to be another order of magnitude lower than that to be comparable to the seasonal flu.
  - goalieca 6y ago
    Uncontrolled? No, but we do know who is most vulnerable and we should be able to make more targeted and surgical measures to limit the negative impacts of social distancing.
skybrian 6y ago
According to the Q&A it is the same test as the Santa Clara study, so concerns about false positives apply equally to both. It seems like they should be doing multiple tests, as independent as possible, per blood sample, and seeing if they agree?
hanniabu 6y ago
> Shady stuff If I'm being honest, whether it's logical or not I wouldn't be surprised if this is politics and misinformation starting to creep it's way into science. In current events there's a struggle to open up the economy with Trump saying we're ready and the that governors are at fault for keeping everything closed while the are governors saying it's way too early and they need to keep everything closed. This may be an attempt to make the public think the situation is safer than it is (if more people have been sick than thought then we could potentially have herd immunity or be closer to it) which the public can then put pressure on the governors. Who knows, but I will say it's getting harder and harder to say some thing are too tin foil hat lately.
- qqqwerty 6y ago
  No tin foil hat required. This is exactly what they are trying to do[1]. [1] https://www.commondreams.org/views/2020/04/20/trumps-reelection-strategy-pit-workers-against-democrats https://www.commondreams.org/views/2020/04/20/trumps-reelect...
8ytecoder 6y ago
This one's from a different company (BioMedomics) and it was a random test of people pulled straight off the streets. Happened at an entirely different geographical area (Chelsea, Massachusetts) as well. I don't want to be too optimistic but there are some signs that we are heavily under-counting the actual number of cases (at least in the US). https://www.bostonglobe.com/2020/04/17/business/nearly-third-200-blood-samples-taken-chelsea-show-exposure-coronavirus/ https://www.bostonglobe.com/2020/04/17/business/nearly-third...
guscost 6y ago
The Imperial College model was also published by press release. That will have ended up doing a whole lot more damage than any of these serosurveys, when all is said and done.
SonOfThePlower 6y ago
Aren't these results consistent with Netherland's findings (3% of blood donors had COVID-19 antibodies) ?

tempsy 6y ago

I’m very skeptical. Why were they so few hospitalizations in LA vs NYC if such a large % in LA contracted Covid? Is this suggesting that a much, much higher % in NYC have it (and the number of those with any serious symptom and thus need for hospitalization was higher)?

teilo 6y ago
Yes, that is the implication. And if this is the case, that is very good news.
SpicyLemonZest 6y ago
Yes. The consensus I've seen forming is that at least 15% of NYC has had it by now - a variety of questionably random samples have suggested numbers near that.
- tempsy 6y ago
  NY has 17x more deaths than California. That would mean if 3% of CA was infected (yes this is LA only but for ease of comparison) it would be 51%+ of NY was infected. Far more than just 15%.
  - arcticbull 6y ago
    CFR is not a great way of comparing across regions, it could be due to any number of factors. Demographics (i.e. age), co-moribidities and the amount of hospital space available.
    - arcticbull 6y ago
      In fact the per-country spread of CFR is huge, from a low of 0.07% in Singapore to a high of 14.93% in Belgium, a whole 3 orders of magnitude. The H1N1 influenza CFR at a similar point in the outbreak was between 0.1% and 5.1% -- but the final IFR ended up at 0.02% [1]. [1] https://www.cebm.net/covid-19/global-covid-19-case-fatality-rates/ https://www.cebm.net/covid-19/global-covid-19-case-fatality-...
  - SpicyLemonZest 6y ago
    The comparison is overweighting LA county, which has 25% of California's population but 60% of its deaths. (I don't know what the math ends up being off the top of my head.)
  - BlackJack 6y ago
    LA is one of the densest parts of CA though, outside of SF/Bay Area. So if LA is 3%, you could assume the state as a whole is maybe 1-2%. Then 17x that becomes 17-34%, which seems more reasonable.
- 6y ago
CydeWeys 6y ago
It's for sure true that a huge number of people in NYC got it, way surpassing the confirmed cases count. The state is currently doing a serology study here and results should be published next week.
- tempsy 6y ago
  Sure I believe NYC has way higher prevalence of cases but difference in deaths would imply majority of population was infected and they’d essentially be at herd immunity now. It’s not implausible but find it hard to believe.
  - CydeWeys 6y ago
    We'll know soon enough. The blood serology randomized trial is underway. I suspect some neighborhoods might be at 50%, but the city overall won't be.
- artursapek 6y ago
  Maybe they'll finally end this ridiculous lockdown when that one is released
strangeloops85 6y ago
I think NYC almost certainly has much large prevalence than LA given hospitalization data alone. One factor could be the nature of transmission. Regions where transmission occurs with high viral loads entering at the point of infection (for example, hospital-acquired infections) could see more severe disease progression. You would therefore expect a high hospitalization rate relative to prevalence. It's possible in other regions, including CA, hospitalization rate as a function of prevalence is lower because acquisition is largely at lower viral loads resulting in less rapid and severe disease progression. This is, of course, a hypothesis and very likely not correct. Time will tell. Other important factors include age distribution of infection, as well as weather conditions and prevalence of pre-existing conditions.
- tempsy 6y ago
  Yes agree NYC will have much higher prevalence but it has 17x the deaths - if fatality rate is similar then it would be like 50%+ of New Yorkers have contracted Covid. Just a little hard to believe.
  - hilbertseries 6y ago
    5.6m people ride the New York subway everyday.
    - tempsy 6y ago
      There’s a decreasing number of positive test cases each day in NYC too though. At highest point was 50% and now under 30% or so. I’m not sure if those tested get the antibody test as well but it implies a larger percentage of symptomatic people are testing negative in nyc.
      - asdf21 6y ago
        Almost no one gets an antibody test yet, unless it's some special controlled study.
    - catlas3r 6y ago
arcticbull 6y ago
In part because all the headline numbers we've seen are CFR numbers which suffer from huge adverse selection bias -- and aren't directly comparable between regions for a lot of reasons. As I've mentioned before, using CFR to determine fatality rate of the disease is like trying to determine the fatality rate of skydiving by measuring the ratio of people who go to hospital with skydiving injuries over those who recover. Obviously you'd think skydiving kills basically everyone who does it, but it just doesn't. It's starting to become clear that the infection fatality rate of COVID is in the lower quartile of the range 0.25-1%. And yeah, a huge portion of New York likely has it. It's super contagious.
- aero142 6y ago
  Define "huge portion" because will still have to square this with the negative test data from NYC.
  - joe_the_user 6y ago
    Yeah, trying to do the basic math on the implications of these figures...[Not claiming they're true, that's a different question] The article says 221,000 infected at a 2.8% rate, in "early April". So they're assuming a 7,892,857 population. Currently, we have 601 Deaths total in LA[1], which we can assume are a result of early april event on April 20. So a 0.002% "fatality rate" relative to total exposures, "Woohoo" (NOTE, this is an optimistic figure implied by this study, the standard 2% [edited] previously claim but still not equivalent to the flu, which has 0.2% [edited] relative people who get sick). Now, with weekly doubling: 221,0008 = 1,768,000 infection now = 22.4% - > 4808 deaths. However, past 10%, we can ask whether we start reaching saturation/diminishing returns. But that is a key question. -- Let's look at NYC. There we have 14,500 Death. Using the article's implied figure, 14,500/ 0.002 = 7,250,000 infected on April 1, out of 8,398,748. So this implies an infection rate of 7,250,000/8,398,748 = 86.32239%, which, in fact, seems very implausible and which implies; a higher death rate among "vulnerable people". Maybe we're about to hit full saturation with NYC and see an immediate decline. Now, the other bad* scenario is the possibility that a lot of sickness and death NOW is being driven by reinfection, that exposure isn't giving much immunity at all and instead of the unexposed dying, what we're seeing is the re-exposed dying and with this dynamic, the death rate settle into a steady and unacceptably high level. Note that Italy, which has seen a high death rate, hasn't a strong drop-off at all, just gradual plateauing. IE, guess what, one possibility is "herd immunity" just doesn't exist for this virus. Anyway, time will tell, literally a week will tell if NYC has enough fatalities to make this 0.002 exposure-to-death rate numerically impossible. [1] covid-19.live Edit: corrected conversion ratio to percentages.
CPLX 6y ago
I think the obvious conclusion (just in logical progression if you take this premise as true) is that the percentage of NYC residents who contracted it was much higher than previously assumed.
- tempsy 6y ago
  Yes but the difference in fatalities is so large that it would imply majority of New Yorkers were infected and the city has achieved herd immunity. It’s not implausible just find it hard to believe.
  - CPLX 6y ago
    It's hard to believe, I would think, because it would be such a remarkably positive development. But just from a logical perspective it follows clearly from this data, and there's nothing fundamental about the situation that makes it particularly unlikely. Of course it's quite possible that the LA data isn't really applicable for any number of reasons. But the idea that COVID will run through dense populations mercilessly, but quickly, and then sort of peter out is completely within the range of possible and non-shocking outcomes. It's the natural outcome of an extremely communicable disease with a large prevalence of asymptomatic transmission and there's plenty of corroborating evidence for the idea that this is one of those. It's also quite likely that the false-positive rate with this test is super high. Who knows.
  - vanniv 6y ago
    If 50% of NYC has had the virus, they won't have herd immunity yet -- of these studies are correct, then the virus is horrendously infectious -- making 90%+ of population required for immunity.
JPKab 6y ago
It needs to be emphasized here: This virus is much more transmissible than the viruses we usually deal with in humans. If a virus has a low fatality rate, but is extremely contagious and prevalent, hospitals will get overwhelmed. A small percentage of a big enough number is itself a big number. The subway and high-utilization of buses are likely factors in NYC vs. LA. LA is much more representative of the typical US city. Frankly, I'm not sure why so many on HN are surprised by this. The scientific data on asymptomatic carriers coming out of Italy, Germany, South Korea, and Iceland has been very clear on a majority asymptomatic frame for this virus. I think that maybe authorities and responsible people are concerned that this information could lead to people flouting lockdowns more.
- arcticbull 6y ago
  Even the Diamond Princess showed a 50+% asymptomatic rate and that group skewed way, way older than average -- you know, people who take cruises.
  - acqq 6y ago
    50? Just initially, but in a week or two more of these developed symptoms, so more recent number was just 18%: https://www.cebm.net/covid-19/covid-19-what-proportion-are-asymptomatic/ https://www.cebm.net/covid-19/covid-19-what-proportion-are-a... "Setting: Diamond Princess cruise ship, Yokohama, Japan (n=-634 tested positive). Proportion: 18%" Also: "23 Residents of a Long-Term Care Nursing Facility King County, Washington 10 (43%) had symptoms, and 13 (57%) were asymptomatic." But then: "Seven days after testing, 10 of 13 asymptomatics developed symptoms" That means that just 3 of 23 remained asymptomatic there too, i.e. 13%. It is estimated that the people mostly spread this virus exactly in the phase where they still haven't developed symptoms, and the virus can be detected. But that doesn't mean they will remain without the symptoms.
    - asdf21 6y ago
      I suspect most people notice a bit of a cold or "allergies" Like you said, probably only 10% to 15% truly asymptomatic.
jjtheblunt 6y ago
Might NYC have more vulnerable people, or more confined spaces for spreading (elevators in high rises, e.g.) ?
smsm42 6y ago
https://www.worldometers.info/coronavirus/country/us/ https://www.worldometers.info/coronavirus/country/us/ right now shows 12850 cases per 1M in NY, which is 1.2%. Which is pretty close to what the study shows for LA. So it's not actually suggesting NY has much more than it's already known, if we assumed overall percentage would be similar for both. It does suggest California - which currently lists 853/mln - undercounts it by more than 10x. Of course, provided that the study is true. Also, having antibodies and being hospitalized is a very different thing. If a lot of the cases are asymptomatic or very light you won't see hospitalizations and you'd never know the person had an encounter with the particular virus until you do mass testing. And NY is quite different from LA, as far as I know, in terms of how dense population can be and how much people use mass-transportation and other high-risk scenarios, and the probability of being hospitalized may also depend on that (in other words, it may matter not only whether you had any contact with the virus, but in which circumstances and how much of the contact you had). That doesn't prove the study is true of course, but I don't see anything from comparison with NY that makes it implausible on its face.
emmelaich 6y ago
LA is far less dense, fewer travel by public transport, and the weather is much warmer. The people are probably healthier too.
pengaru 6y ago
Just speculating here but I hung out with some NYC folks last month in SoCal and they practically all smoked. It was very strange, I rarely encounter smokers living in California.
- catlas3r 6y ago
  Cigarette smoking rate is widely studied; no reason to use anecdotal data here. The tobacco smoking rate in New York is 14.1%; it's 11.3% in California. Some difference, yes, but far less difference than you see between either and some rural southern states where the numbers can be roughly double that. https://www.cdc.gov/statesystem/cigaretteuseadult.html https://www.cdc.gov/statesystem/cigaretteuseadult.html
closeparen 6y ago
Case fatality rate is # of deaths / # of positive tests. It’s enormously biased by the availability of testing, and the allocation of the tests we have to the sickest people. It’s not especially likely to generalize to the population at large. We need large scale random sampling of the population for that. Everyone is eager for these results, because there’s a good chance that the true case count is higher by anywhere from 2x to 100x. If it is, then proportionally fewer people are expected to die as the virus eventually does churn through the whole population. It’s probably still too early to tell, but this is promising.
DeonPenny 6y ago
No the very obvious conclusion is that covid-19 isn't very deadly. Thats what every test has concluded. Its that the death rate is closer to .3% than the 3% that the WHO quoted and much closer to the flu's death rate of .1%

elihu 6y ago

> Another interesting aspect of the result was 6% of men showed antibodies but only 2% of women tested. That is interesting. So far, men are more likely to die of covid-19 (almost a 2:1 ratio) than women; if this is a repeatable result it would seem to suggest that the reason is that fewer women are becoming infected, not that women are somehow less likely to exhibit extreme symptoms when infected.

guscost 6y ago
Or that women are less likely to need antibodies to clear this infection. Not everyone develops antibodies for every disease, the immune system is super complicated.

herf 6y ago

Premier is an importer for "Hangzhou Biotest Biotech Co". Most of the validation data in the Stanford preprint also appear in this sell sheet: http://img.bj.wezhan.cn/content/sitefiles/2005911/images/13248611_IMG_9396-20200328-102944.jpeg http://img.bj.wezhan.cn/content/sitefiles/2005911/images/132... Stanford reports doing a 30-person validation test with pre-COVID-19 hip surgery patients (100% negative). But this is not enough to validate these population-scale tests, especially when 98.5% specificity (rather than 99.5%) would fully invalidate the headline result.

zby 6y ago
> Stanford reports doing a 30-person validation test with pre-COVID-19 hip surgery patients (100% negative) Hmm - I guess I should now go to the source - but from the other link: " test validation included a total of 30+371 pre-covid blood tests, and only 399 of them came back negative." https://statmodeling.stat.columbia.edu/2020/04/19/fatal-flaws-in-stanford-study-of-coronavirus-prevalence/ https://statmodeling.stat.columbia.edu/2020/04/19/fatal-flaw... - I think I trust it more
- herf 6y ago
  Yes, the 371 are listed on the sell sheet (see tweet above). Unclear if Stanford was involved, but I would suspect not.

goalieca 6y ago

Our initial policy was based on early data from China which seemed to imply 3% mortality, an R0 of 2.4 and a 5% hospitalization rate. In the past month, data from all sources and methods is showing this to be far less deadly but also far more contagious. Perhaps it’s time to adjust our view of the lockdown.

usaar333 6y ago
Well, R0 is probably still about 2.4 in most cities in the United States (NYC, like Wuhan, considerably higher). Source suggesting this: https://www.medrxiv.org/content/10.1101/2020.04.12.20062943v1.full.pdf https://www.medrxiv.org/content/10.1101/2020.04.12.20062943v... I think it has been pretty obvious that IFR is not 3% for a long time. Imperial College had dropped it to 0.67% in China 3 weeks ago (https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30243-7/fulltext https://www.thelancet.com/journals/laninf/article/PIIS1473-3...)
Jeema101 6y ago
I think the view that the infection fatality rate is significantly lower than the case fatality rate has already been factored into public policy. Because even if the IFR is around 0.5% then that still works out to > 1,000,000 people dead in the US in an uncontrolled spread scenario. It would have to be another order of magnitude lower than that to be comparable to the seasonal flu.
- goalieca 6y ago
  Uncontrolled? No, but we do know who is most vulnerable and we should be able to make more targeted and surgical measures to limit the negative impacts of social distancing.

skybrian 6y ago

According to the Q&A it is the same test as the Santa Clara study, so concerns about false positives apply equally to both. It seems like they should be doing multiple tests, as independent as possible, per blood sample, and seeing if they agree?

hanniabu 6y ago

> Shady stuff If I'm being honest, whether it's logical or not I wouldn't be surprised if this is politics and misinformation starting to creep it's way into science. In current events there's a struggle to open up the economy with Trump saying we're ready and the that governors are at fault for keeping everything closed while the are governors saying it's way too early and they need to keep everything closed. This may be an attempt to make the public think the situation is safer than it is (if more people have been sick than thought then we could potentially have herd immunity or be closer to it) which the public can then put pressure on the governors. Who knows, but I will say it's getting harder and harder to say some thing are too tin foil hat lately.

qqqwerty 6y ago
No tin foil hat required. This is exactly what they are trying to do[1]. [1] https://www.commondreams.org/views/2020/04/20/trumps-reelection-strategy-pit-workers-against-democrats https://www.commondreams.org/views/2020/04/20/trumps-reelect...

8ytecoder 6y ago

This one's from a different company (BioMedomics) and it was a random test of people pulled straight off the streets. Happened at an entirely different geographical area (Chelsea, Massachusetts) as well. I don't want to be too optimistic but there are some signs that we are heavily under-counting the actual number of cases (at least in the US). https://www.bostonglobe.com/2020/04/17/business/nearly-third-200-blood-samples-taken-chelsea-show-exposure-coronavirus/ https://www.bostonglobe.com/2020/04/17/business/nearly-third...

guscost 6y ago

The Imperial College model was also published by press release. That will have ended up doing a whole lot more damage than any of these serosurveys, when all is said and done.

SonOfThePlower 6y ago

Aren't these results consistent with Netherland's findings (3% of blood donors had COVID-19 antibodies) ?