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

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

#531

Post by greedo »

amalter wrote: post #328
TechBro8615 wrote: post #96

So, at what point can we declare the lockdown to be a harmful overreaction and start opening countries up? Will we hold anyone accountable for models which proved to be pessimistic by orders of magnitude, causing implosion of economies around the world?

That the 0.5% death rate in NYC is not higher is _because_ of the pause. We saw the death rates spike at the peak of the curve. We saw the hospitals near total collapse. We even have an example of what would happen if we didn't flatten the curve (Northern Italy). We have another counterexample of California that shows NY's pause was late. I guess Sweden is the counter-counter example. I think the US would have needed…

I'm holding judgement on Sweden since their numbers don't look as good as people are claiming, and the pandemic is still young.

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

#532

Post by greedo »

bbarn wrote: post #230
TechBro8615 wrote: post #96

So, at what point can we declare the lockdown to be a harmful overreaction and start opening countries up? Will we hold anyone accountable for models which proved to be pessimistic by orders of magnitude, causing implosion of economies around the world?

At the point where more deaths are caused by the global socio-economic collapse than COVID-19 would have caused at even pessimistic projections. At this point, I'm not convinced in either direction.

You're assuming the economy wouldn't have collapsed in the faced of the pandemic.

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

#533

Post by Uhhrrr »

GhostVII wrote: post #486
Uhhrrr wrote: post #468

Earlier quoted context omitted.

It will probably be significantly higher than 60%, since COVID-19's R0 without lockdown seems to be pretty high. The CDC has estimated it at 5.7 [0]. Herd immunity threshold = 1 - 1/R0, so the threshold would be 82.4%. [0] https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article?deliv...

That R0 assumes we are taking essentially no measures to stop the virus though, right? I don't no much about it but it seems like the R0 would drop significantly if we keep doing social distancing, expand testing, make people wear masks, etc.

It does, but the point of getting to herd immunity is that we don't want to do any of that other stuff.

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

#534

Post by mlyle »

fspeech wrote: post #483
__blockcipher__ wrote: post #464

Earlier quoted context omitted.

Young people interact with more individuals, and engage in more behavior that exchanges microbes such as unprotected sex, protected sex, sharing pipes/vapes, sharing utensils, etc. We should expect that the proportion of people with Covid should be heavily biased towards the young for that reason, as it is for any disease that does not have a biased transmission. Most indications I've seen is that the young are not h…

For any test that is not given randomly or universally, there is a selection bias. A test given based on severity of symptoms bias heavily against patients with light symptoms, presumably younger people. But to get from 7% (hospitalized to confirmed) to 1 in 500 is a factor of 35. BTW the city of Canton (Guangzhou) just tested all their high school seniors in preparation for school reopenning and found zero positive…

> But to get from 7% (hospitalized to confirmed) to 1 in 500 is a factor of 35.

This is broadly in the range implied by a number of measures across the entire population. 20x for randomized population sampling (Iceland), 20-80x from serology studies, etc.

In this analysis, https://www.medrxiv.org/content/10.1101/2020.04.18.20070821v... 35x is actually the exact factor that cases are estimated to be under-reported by in California. :P

> I don't think anyone enjoys lockdown. At a minimum we need sufficient testing, sufficient ppes, sufficient surge capacity and training for standard supportive care.

Here in the SF Bay Area, ICU usage peaked 3 weeks ago, and controls have been tightening. We're well below seasonal norms for ICU usage at this point. Surely the original controls that caused the original trend down in disease would be good enough now, and could even be loosened slightly further to have more parity with other jurisdictions that are successful.

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

#535

Post by slv77 »

mynegation wrote: post #424
slg wrote: post #386

Earlier quoted context omitted.

I'm no expert here, so someone can correct me if I am wrong. But I believe as long as each infected person spreads it to more than 1 other non-infected person the disease will continue to spread until there is a herd immunity level of infections. That spread rate will decrease as more people have antibodies, but it seems unlikely to get below 1 since even all the stay at home orders haven't been able to get that numb…

Sustained spread of the infection stops when percentage of people having immunity is 1-1/R0. So if R0 for Covid-19 is (hypothetically) 3, you need 67% immunity to reach herd immunity. For highly contagious diseases like smallpox that number is very close to 100%

The 1-1/R0 is the point that the virus starts to burn out but there is still a long tail of infections. The total population that is infected will be higher than 1 - 1/R0. Also if the estimates of IFR were too high than the estimates of R0 were too low.

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

#536

Post by killion »

t2riRXawYxLGGYb wrote: post #326
aazaa wrote: post #317

> 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/Ro…

This was my thought exactly. Some of my friends in the Bay area got COVID-19 (confirmed positive tests) after quarantining for over two weeks at home and taking all of the precautions. The only place they had been was the grocery store, so they suspect that they got it there.

I'm in the East Bay and was quarantining for almost a month before my symptoms showed. I also assume I got it at the grocery store since that was my only outing.

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

#537

Post by __blockcipher__ »

maxerickson wrote: post #476
__blockcipher__ wrote: post #444

Earlier quoted context omitted.

We use the term "immunity" but we should remember that there is a difference between the presence of active antibodies and the presence of immune "memory cells". The latter hang around long-term, even if the former disappear. So at a minimum if one does develop infection they will recover far sooner and with better outcomes. And likely will reach a far lower peak viral load which might bring down transmission.

That is not well established. It's likely enough, but we don't gain long term immunity to every virus that we successfully clear.

It is well established.

https://en.wikipedia.org/wiki/Memory_T_cell

You are conflating active circulating antibodies with the memory T cells. Which is literally what my entire comment was about.

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

#538

Post by unishark »

mlyle wrote: post #429
slg wrote: post #405

Earlier quoted context omitted.

I skimmed through that so please point it out if I missed it, but the numbers don't seem to account for comorbidities. The question was whether COVID-19 is more dangerous than the flu to healthy young people not all young people.

Just because you've not heard about it, doesn't mean it doesn't happen. Seemingly healthy young people die from the flu each year. Since Feb 1, 204 people from 15-34 have been confirmed to have died from COVID-19 in the US. 162 people from age 15-34 have been confirmed to have died from influenza in the same period. I don't think you'll find either statistic broken down by comorbidities.

Not sure why you added the lower limit at 15. The two high risk age groups from influenza are 65+ and under 5. If I recall correctly, pediatric flu deaths are the only ones tracked by the CDC (for other age groups they just use statistical estimates).

There is data on comorbities with the flu from prior years. This article says half of deaths had no preexisting medical conditions.

https://pediatrics.aappublications.org/content/141/4/e201729...

And the deaths among healthy young people from both kinds of viruses is commonly blamed on the cytokine storm:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4711683/

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

#539

Post by akiselev »

CydeWeys wrote: post #433
TheBlight wrote: post #413

Earlier quoted context omitted.

We don't have perfect studies and perfect data but calling these tests "bad" seems slightly unfair. They give us an imperfect but useful snapshot of what's going on. But thanks for the condescension. I'd expect nothing less on HN.

The study is dramatically over-sampling exactly the people who have the most potential exposure to COVID-19, and dramatically over-sampling the people who don't. This could easily be way off. It's not testing the people who aren't home at all, and it has a low chance of only testing the people who leave home rarely, only when strictly necessary. It's mainly finding the people who leave home a lot.

Couldn't you get a bad study that reverses the sampling bias to get a decent picture of social distancing strategies using the two bad studies? That alone seems far more useful than knowing the IFR because its actionable information.

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

#540

Post by bagacrap »

ferzul wrote: post #158
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…

otoh, it gives about the same ifr as the recent study in geneva. at the end of the day, it looks like the first wave will have an ifr of about 0.6% - more than ten times greater than the flu, but not the bubonic plague

that's not more than 10x...
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