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

#361

Post by Gibbon1 » Thu, Apr 23, 2020, 9:20 PM UTC

mlthoughts2018 wrote: post #192

mlthoughts2018 wrote: post #181

Earlier quoted context omitted.

The rates being this high actually casts doubt on the study. It’s very very implausible, and suggests almost surely a selection bias in the sample towards a population much more likely to have contracted it.

Actually in reading closer and seeing the data is collected at big box & grocery stores, it’s almost surely very biased. This cohort would skew younger and wealthier, which correlates with better preexisting health and fewer risk factors, and would exclude populations who systematically left the city, or who have known heightened risk factors. Comparing the death rate overall with the infection rate of this skewed sa…

This weekend San Francisco plans to do a hard test of about 6000 people in a couple of square blocks of the Mission district. They are going door to door to encourage people to get tested.

Still biased but probably better than anything so far.

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

#362

Post by matwood » Thu, Apr 23, 2020, 9:21 PM UTC

credit_guy wrote: post #316

robocat wrote: post #174

Earlier quoted context omitted.

> 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…

> 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

MERS is also a coronavirus and does just fine in the warm climate of the middle east. I hope that warmer temps slow the spread, but it's far from certain.

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

#363

Post by hcknwscommenter » Thu, Apr 23, 2020, 9:21 PM UTC

zaroth wrote: post #338

athrowaway3z wrote: post #297

Earlier quoted context omitted.

What? All of these numbers are inline with what experts have been saying and modeling for more than a month. We will be dealing with this for at least another year. We will cycle through policy to loosen up and close back down a little. In the best case for NYC they are 1/4th of the way to herd immunity in numbers. With the drop in transmissions, this might be 1/8th of the way in terms of time. There will be more dea…

25% prevalence is absolutely not in line with what experts were saying on March 23rd. Nor was an IFR of 0.5%. The CDC reports that flu has an IFR of ~.13% in the US (61,000 deaths out of 45 million cases). That makes 0.5% roughly 3.3 times worse, not 10. Also, herd immunity does not require 100% having positive antibodies, it will show an effect on Ro starting around 65%.

It's not 25%. 0.5% versus 0.13% is not the only issue here in terms of how much worse it is. It's the long time in the ICU. The flu kills you fairly quickly or you get better fairly quickly, so you don't take up hospital capacity so long. Herd "immunity" does not require 100%, but that's a decent approximation. Sure, I'll grant that it "starts" to show an effect around 65%, but the effect is not so strong. 70%, much stronger. 80% very strong. Heck, you could probably do containment by then without waiting to get to 100%. Because inadvertent spreading would be so low.

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

#364

Post by usaar333 » Thu, Apr 23, 2020, 9:22 PM UTC

djrogers wrote: post #93

vkou wrote: post #24

If this study is accurate, and is not just working on garbage data, and if these antibodies actually mean long-term immunity, this means one of two things: 1. If the lockdown is lifted, we will see another ~60,000 to 100,000 deaths in NYC, before it will hit herd immunity. 2. Or, the lockdown will continue. The accuracy of antibody studies has been called into doubt, and as far as I know, nobody has ever followed up…

The purpose of the lockdown isn't to hide until the virus magically disappears, it's to flatten the curve and allow the virus to spread slowly enough that it doesn't overwhelm the healthcare system in any given place. Maintaining a lockdown will not lower the number of people who get the virus, it will merely extend how long it takes to get there.

Matters where you are. The Bay Area is keeping their lockdown up so they can contact trace and crush any infection spike. Otherwise, we're going to be locked down until a vaccine at the current new case rates.

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

#365

Post by qqqwerty » Thu, Apr 23, 2020, 9:22 PM UTC

electricviolet wrote: post #200

qqqwerty wrote: post #150

Earlier quoted context omitted.

The only good news that I am getting out of this, is that NYC seems to have avoided the dreaded 3-5% fatality rate that was the presumed worse case scenario (massive community spread, overloaded healthcare system). But the lockdown likely helped a lot, and it seems like they are seeing around 1% IFR, so I am not sure this really changes anything. Our understanding of the disease and how to treat it may also be gettin…

If the infection rate were 50% we would be close to herd immunity (which I've read would require about 70% for this virus), so that would be better news in a sense. Unfortunately 21% is a long way from 70%, and it's taken a massive amount of death to get to that point.

The R0 value impacts herd immunity %. So if NYC is already at 50%, then it means R0 is much higher than we thought, which means herd immunity would probably be as high as +90%. With numbers like that, not shutting down would result in the entire population getting infected in the span of a month or two.

The point I was trying to make, was that for the 'open back up' crowd, they are arguing that the IFR is similar to the flu, and only vulnerable populations are really impacted. So they say we should open up and just keep vulnerable population in lockdown. But they are ignoring the implications of the R0 value in their argument. i.e. if the IFR is really as low as they think (and consequently, the infected population is as high as they think), then nothing short of a total lockdown (or very aggressive testing and contract tracing) would stop vulnerable populations from getting infected.

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

#366

Post by arcticbull » Thu, Apr 23, 2020, 9:23 PM UTC

slg wrote: post #360

TheBlight wrote: post #348

Earlier quoted context omitted.

Sure all of these studies are potentially flawed but they're all generally pointing in the same direction. There are many more infections than we know about and the CFR is not anywhere close to the actual IFR. NYC is an outlier with a 21% infection estimate but for the rest of NY (outside NYC metro/Westchester/LI) the estimate is 3.6%. Santa Clara estimate was 3%. LA County estimate was 4%. Seems like a trend is deve…

>There are many more infections than we know about and the CFR is not anywhere close to the actual IFR. That is the optimistic takeaway. The pessimistic takeaway is that even the hardest hit areas are nowhere near herd immunity levels and that we are either going to be isolating until a vaccine is created or we can expect to see a lot more death once nonessential people are forced back to work.

> The pessimistic takeaway is that even the hardest hit areas are nowhere near herd immunity levels and that we are either going to be isolating until a vaccine is created or we can expect to see a lot more death once nonessential people are forced back to work.

The third option is, when you take into account that it's approximately as bad as the flu for folks under 40, we let out the young and keep the older folks and the vulnerable inside. This will boost our progress towards herd immunity without materially increasing the death counts.

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

#367

Post by zaroth » Thu, Apr 23, 2020, 9:23 PM UTC

kgwgk wrote: post #177

revnode wrote: post #129

Earlier quoted context omitted.

> Sorry, can someone spell out how this might be good news? It's good news because it strongly suggests that mortality is much less than previously suspected. There were numbers floating around from anywhere between 10% to 3% a few weeks back. A mortality rate < 1% is very good news because it means fewer people will die in the long run.

> mortality is much less than previously suspected Mortality remains pretty much as suspected already two months ago: “Based on these available analyses, current IFR estimates10,11,12 range from 0.3% to 1%. Without population-based serologic studies, it is not yet possible to know what proportion of the population has been infected with COVID-19.” https://www.who.int/docs/default-source/coronaviruse/situati...

Two weeks after that the WHO released a widely cited report claiming a fatality rate of 3.4%.

“Globally, about 3.4% of reported COVID-19 cases have died. By comparison, seasonal flu generally kills far fewer than 1% of those infected.”

https://www.who.int/dg/speeches/detail/who-director-general-...

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

#368

Post by RandallBrown » Thu, Apr 23, 2020, 9:23 PM UTC

analyst74 wrote: post #319

fyp wrote: post #170

Earlier quoted context omitted.

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"

The non-spreaders are the people who are self isolating.

I think they're saying that people who go out and spread the disease will quickly catch it, recover, and be unable to catch it and spread it. That relatively small group of people who are refusing to self isolate, will gain herd immunity, causing the virus to die out in that group of people, preventing them from giving it to the non-spreaders that have been at home the whole time.

Whether or not it will work out that way, I don't know.

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

#369

Post by newacct583 » Thu, Apr 23, 2020, 9:24 PM UTC

mediaman wrote: post #273

dragonwriter wrote: post #262

Earlier quoted context omitted.

> If this study is accurate, then 1.8 million NYC resident are infected. So 10 290 deaths (as of today) suggests COVID-19 has a fatality rate of 0.6% No, it doesn't, because the usual time to death, if it causes death, isn't zero, so you need to compare the number of deaths a couple weeks from now with the number of infections today to get a closer-to-accurate number. Also, you are using the 10,290 confirmed deaths a…

Interesting thought experiment: if NY daily deaths over the next two weeks average 400, that's 5,600 upcoming deaths from people presumably infected now. If about one-third of deaths are not accounted for (5,121 unidentified as a portion of identified+unidentified), then we'd have about 8,400 new deaths projected over two weeks including the likely unidentified deaths. As a percentage of those who were infected as of…

You can derive that from better data. From https://covidtracking.com/ we can see that 57k people have been hospitalized in New York State so far, with 15k still in the hospital. Of the 42k who aren't, 16k died[1], so we'd expect that about 5k of the people currently in the hospital won't be coming home (some of these statistics are pretty depressing).

So two methods give us similar counts, matching up very closely with the separately measured CFR from way back in the original outbreak. That's pretty good back-of-the-envelope work.

[1] this isn't quite right as not every fatality was a hospitalized case.

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

#370

Post by CubsFan1060 » Thu, Apr 23, 2020, 9:25 PM UTC

slg wrote: post #360

TheBlight wrote: post #348

Earlier quoted context omitted.

Sure all of these studies are potentially flawed but they're all generally pointing in the same direction. There are many more infections than we know about and the CFR is not anywhere close to the actual IFR. NYC is an outlier with a 21% infection estimate but for the rest of NY (outside NYC metro/Westchester/LI) the estimate is 3.6%. Santa Clara estimate was 3%. LA County estimate was 4%. Seems like a trend is deve…

>There are many more infections than we know about and the CFR is not anywhere close to the actual IFR. That is the optimistic takeaway. The pessimistic takeaway is that even the hardest hit areas are nowhere near herd immunity levels and that we are either going to be isolating until a vaccine is created or we can expect to see a lot more death once nonessential people are forced back to work.

I don't think this a binary outcome. Getting closer to herd immunity also makes things better. Take NYC. Now 1 out of 5 people you see can't infect you (assuming having antibodies means immunity). The closer we get, the better it is. Having 21% "immune" leads to far different outcomes than .1%.