Preliminary test results suggest 21% of NYC residents have Covid antibodies • Hacker News Board

Re: Preliminary test results suggest 21% of NYC residents have Covid antibodies

#311

Post by Symmetry » Thu, Apr 23, 2020, 8:42 PM UTC

mrb wrote: post #183

If this study is accurate, then 1.8 million NYC resident are infected. So 15 411 deaths (as of today, including 5 121 probable deaths) suggests COVID-19 has a fatality rate of MINIMUM 0.9% which is in line with previous estimates (between 0.5 and 1.6%) and this is MINIMUM 9 times more fatal than the flu (0.1%). Edited to add "MINIMUM", as there is a lag between case detection and death (I should have known better to…

I hope that the numbers stay at .6% and that the difference from previous estimates might even be improvements we've made in figuring out how to care for people suffering from Covid-19. But I remember being happy at how low South Korea's numbers were when their epidemic peaked and receded then watching the case fatality rate slowly climb up to the 2.2% it's at today. So I'm not counting any chickens just yet.

Re: Preliminary test results suggest 21% of NYC residents have Covid antibodies

#312

Post by TheCowboy » Thu, Apr 23, 2020, 8:44 PM UTC

klmadfejno wrote: post #204

daxfohl wrote: post #72

I find myself reconsidering the original proposition by England to isolate the most vulnerable for a couple months and let the virus work its course through the less vulnerable population. If death rate is substantially lower among the under 50 crowd, this could work its way through with a fairly low death toll, and result in a herd immunity within a couple months. This slow burn approach we're doing however seems po…

I've been making many posts arguing against the efficacy of lockdowns (and been getting shat on by points I find mostly naive). I think something like this is probably the best approach because it minimizes economic harm while also trying to minimize hospitalization rates among the elderly. But even if we pretend we could implement a perfect bubble for everyone over 50, they're not especially safe when the lockdown i…

> I've been making many posts arguing against the efficacy of lockdowns (and been getting shat on by points I find mostly naive).

I skimmed some of your comment history. Your comments aren't as rock solid as you believe, and there are many points either glossing over things or complete ignorance.

> More people will die if the lockdown is lifted, and many of those who would have died anyway will die sooner.

Are you really arguing many would have died anyways? How many? What percent? You're ignoring the reality that in regions with overwhelmed healthcare systems they're having to engage in triage (read: many people are dying who would not have died anyways) since they cannot treat everyone. This isn't just for covid-19, but for people with other treatable conditions.

Re: Preliminary test results suggest 21% of NYC residents have Covid antibodies

#313

Post by lettergram » Thu, Apr 23, 2020, 8:45 PM UTC

I’ve continuously questioned the antibody tests...

My understanding (from NBC news) was that at least some of the antibody tests were derived from a couple who were on the princes cruise. They never showed symptoms, but tested positive. IMO it’s quite possible that they never had it and those tests were inaccurate (right at the start of the outbreak, no symptoms, etc).

Further, these antibody tests likely weren’t fully vetted nor were the samples they derived it from. For instance how often does another coronavirus set off this antibody test?

Personally, I’m just waiting to see. I actually do suspect 20% have been infected, so it fits my expectations, but that’s not validation.

Re: Preliminary test results suggest 21% of NYC residents have Covid antibodies

#314

Post by smartmic » Thu, Apr 23, 2020, 8:45 PM UTC

ccleve wrote: post #17

This study doesn't appear to suffer from the same methodology problems as the Stanford study of a few days ago. In that study, they recruited people through Facebook, and reported an infection rate that was low enough that it could have been caused by false positives. Here, it's closer to a random sample, but more importantly it shows really high rates. Those rates overwhelm any error due to false positives. Also, it…

What I learned from an article of a major German newspaper is that in order to really estimate the quality of testing, two criteria are important: sensitivity and specifity of the applied test.

If the real infection rate is still low throughout the population, a random sampling will not lead to reliable results (you could also toss a coin).

Although the article is in German, it is worth to have a look on the graphic in the middle of the page, it should be understandable.

https://www.sueddeutsche.de/gesundheit/corona-test-antikoerp...

Re: Preliminary test results suggest 21% of NYC residents have Covid antibodies

#315

Post by ineedasername » Thu, Apr 23, 2020, 8:47 PM UTC

CodeWriter23 wrote: post #182

ineedasername wrote: post #98

Earlier quoted context omitted.

I couldn't find any detailed write up about their selection methods for participants, only the basics of where they found them. Without that, it is very hard to determine whether or not there's some flavor of selection bias: If it is voluntary, and they do not screen out people who report having had cold/flu symptoms, then they run the risk of attracting a disproportionate number of people who volunteer because they'…

I argue there is inherently less sampling bias in this study than testing people at the hospital who have shown up due to severe symptoms.

Those are the people who constitute the denominator for the CFR. It's a completely different metric. You would never try to impute population exposure from such cases. This study is trying to to impute population exposure. There isn't any comparison between the two in terms of which has more/less selection bias, they are completely different things.

Re: Preliminary test results suggest 21% of NYC residents have Covid antibodies

#316

Post by credit_guy » Thu, Apr 23, 2020, 8:49 PM UTC

robocat wrote: post #174

credit_guy wrote: post #122

Earlier quoted context omitted.

Yes, the study is really good news for NYC. My thinking is that the state of emergency, currently in place until 5/15, will be extended at most once to 6/15. After that we'll be somewhat open for business. I imagine everyone will be advised to wear mask/gloves, to keep the social distance and to keep washing hands. Lots of people will continue to work from home, others will bike to work. Being summer, the virus will…

> Being summer, the virus will not be that contagious. I think that is still scientifically debatable, good overview: https://www.newscientist.com/article/2239380-will-the-spread... Certainly it is still transmissible in hot countries.

Thanks for the link. It's a good read.

That said, science is enamored with significance levels, p-values, etc. Most people just do that because that's what they've learned, and think that's how it should be done. They don't think it comes from Bayesian inference, where you put a very low prior probability of a drug being useful (because the very vast majority of chemicals we could put in our bodies are either harmful, or have harmful side-effects). In this case, the Bayesian prior is that common colds in general become less prevalent during the Summer, and Covid19 is caused by a coronavirus, which is related to viruses causing the common cold. The burden of proof should be lowered many, many times, but I nobody who did these statistical surveys did that, because this is a total no-no in the field.

So, I'll state my conclusion, after reading your link: the infectiousness of Covid19 is more likely than not to decrease in the Summer, based on the studies that were performed. It will not decrease to zero, so that does not contradict your statement that it is transmissible in hot countries.

Re: Preliminary test results suggest 21% of NYC residents have Covid antibodies

#317

Post by aazaa » Thu, Apr 23, 2020, 8:50 PM UTC

> In his press conference today, Governor Cuomo revealed the preliminary results of a first-phase antibody test that surveyed 3,000 New Yorkers over two days in 19 counties at 40 locations that included grocery and big-box stores. The sample suggests that 13.9% of New York State residents have the antibodies, meaning they had the virus at one point and recovered. Of the regions tested–Long Island, NYC, Westchester/Rockland, and the rest of the State–New York City had the highest positive rate at 21.2%. The potential good news to come to light is that the death rate may be far lower than some estimates, at 0.5%.

This still is not a random sampling. It only samples from shoppers at grocery stores and big-box retailers. Imagine doing the same study, but of people who ordered groceries online only. Would you expect to see big differences in exposure rate? I think so.

The study itself isn't linked anywhere, nor have I seen it elsewhere. Science is all about the details. It's not hard to imagine half a dozen ways that the bottom line result of this study could have been skewed by decisions made by the study authors and ground team.

Re: Preliminary test results suggest 21% of NYC residents have Covid antibodies

#318

Post by gridlockd » Thu, Apr 23, 2020, 8:52 PM UTC

grumple wrote: post #135

cm2187 wrote: post #2

Another datapoint suggesting the death rate of this virus is within 0.5%.

The death rate would go up if more people had the virus at once, which is the entire reasoning behind isolating.

I am wondering that number, if the limiting factor is ventilators, but the CFR of people on a ventilator is close to 90% either way.

Other cases may just need oxygen supplementation, which is more manageable.

It is pretty clear now that Germany is not that far from from Italy in terms of CFR when controlled for age.

Re: Preliminary test results suggest 21% of NYC residents have Covid antibodies

#319

Post by analyst74 » Thu, Apr 23, 2020, 8:52 PM UTC

fyp wrote: post #170

cjhopman wrote: post #55

Earlier quoted context omitted.

Sure, but a person who goes to the store 7 times a week is ~7 times as likely to have been sampled compared to someone who goes only once a week. They are also ~7 times as likely to have contracted covid-19 at the grocery store. It's likely that they are also, in general, isolating less than the other. This sampling would have a (possibly slight, but still unknown) bias towards people who are isolating less (who you…

Even with worst-case scenario of bias, this is still extremely good news. My worry was always with super spreaders who refuse to isolate but the data is suggesting that those spreaders will still soon achieve herd immunity among themselves. As long as the rest of the society behaves we will still hit zero cases relatively quickly. (which wasn't always clear to me before since I initially predicted that this will take…

> those spreaders will still soon achieve herd immunity among themselves

that's not what herd immunity means, unless we isolate those spreaders so they don't get in touch with "non-spreaders"

Re: Preliminary test results suggest 21% of NYC residents have Covid antibodies

#320

Post by TheCowboy » Thu, Apr 23, 2020, 8:52 PM UTC

formercoder wrote: post #234

klmadfejno wrote: post #204

Earlier quoted context omitted.

I've been making many posts arguing against the efficacy of lockdowns (and been getting shat on by points I find mostly naive). I think something like this is probably the best approach because it minimizes economic harm while also trying to minimize hospitalization rates among the elderly. But even if we pretend we could implement a perfect bubble for everyone over 50, they're not especially safe when the lockdown i…

Any time I try and make counterpoints to lockdowns or even logical evaluations of them online the downvotes and hate start flowing. There is a huge bias among those in our circles towards locking down as long as possible, because all of us can work from home and aren’t worried about feeding our families.

Arguing it's a matter of bias sidesteps the reasoning for lockdowns. This is like when someone dismisses someone for possessing a political bias---that's not an argument.

And framing it as lockdown vs. being able to feed your family is a false dichotomy. It seems like a waste to even get into the finer details if this is where you're coming from, but keep calling it hate while ignoring the criticism.