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The study that showed 21% positive antibody results came from self-selected testing of people physically shopping at grocery and big-box stores. Unfortunately, that ultimately doesn't effectively represent the overall population of NYC at all. This was posted by the Head of Decision Intelligence at Google about the study a day after the "21%" headline was published: https://towardsdatascience.com/were-21-of-new-york-city-resi...

> Unfortunately, that ultimately doesn't effectively represent the overall population of NYC at all.

Yes, as the Google article points out, the study is probably an undercount. IIRC, the samples were taken from mid-day grocery shoppers. If so, this would push the real NYC IFR higher, possibly into the 2% range. And as the Diamond Princess has shown, the real IFR continues to climb for weeks, as the final ICU patients succumb.

This would make the ultimate costs of herd immunity higher.

> I did the math last week, and 0.2% of New York City had died either from the coronavirus, or from something that was probably the coronavirus

"Something PROBABLY was the coronavirus?". So you're from the camp of "someone was shot 9 times, so he died from corona virus". I question the way you calculate the numbers.

That's not how that works.

It's also most likely still an undercount. Confirmed plus probable cases are thousands short of total excess deaths for that period for New York City.

Ascribing all excess deaths to coronavirus is a mistake. People are avoiding ERs and doctors; the incidence of typical CVA, MI, etc, in hospitals is way down. Not because we're having fewer CVAs and MIs, but because people are dying at home instead of being treated.

(Prolonging the epidemic increases the number of people who will die this way, too).

> Ascribing all excess deaths to coronavirus is a mistake.

I worded my statement intentionally.

> It's also most likely still an undercount

Some of the excess deaths will be other things. It will take more careful analysis to come up with reasonable breakdowns, and what percentage is likely covid-19 deaths.

Basically, as this article mentions - https://www.washingtonpost.com/investigations/2020/05/02/exc...

> “I think people need to be aware that the data they’re seeing on deaths is very incomplete,” said Dan Weinberger, a Yale professor of epidemiology who led the analysis for The Post.

> Those excess deaths — the number beyond what would normally be expected for that time of year — are not necessarily attributable directly to covid-19, the disease caused by the coronavirus. They could include people with unrelated maladies who avoided hospitals for fear of being exposed or who couldn’t get the care they needed from overwhelmed health systems, as well as some number of deaths that are part of the ordinary variation in the death rate. The number is affected by increases or decreases in other categories of deaths, such as traffic fatalities and homicides.

> But excess deaths are a starting point for scientists to assess the overall impact of the pandemic.

> "Something PROBABLY was the coronavirus?". So you're from the camp of "someone was shot 9 times, so he died from corona virus".

Specifically, I counted COVID-19 "confirmed deaths" plus "probable deaths" from https://www1.nyc.gov/site/doh/covid/covid-19-data.page. The probable deaths are defined as:

> People who did not have a positive COVID-19 laboratory test, but their death certificate lists as the cause of death "COVID-19" or an equivalent.

Since tests are scarce, they're not necessarily being used to confirm people who died at home or who died during triage. But COVID-19 is pretty distinctive, and in any case, the COVID-19 deaths are only a portion of the excess mortality.

> About 21% percent of New York City was testing positive for antibodies.

From samples returned 10 days ago, so add a bit more lag.

It's not beyond the realm of possibility that New York City has reached the herd immunity threshold. The biggest estimates of variance in contact networks and susceptibility (from fitting to case count data) predict a herd immunity threshold of ~15%. (Cited above).

> We don't seem to be able to ramp up testing

Testing, shmesting. It only provides a minimal adjustment to Rt; sensitivity isn't great, and you can't test everyone every day.

> we haven't gotten the infection rate down to the point where contact tracing would work

Nor will we. The most aggressive lockdowns produce case count decays of 40% or so per week-- possibly less. The suggested threshold for where contact tracing can work well is 1 infection per million population. The SF Bay Area probably has about 3500x that. -ln(3500)/ln(0.6) =~ 16 weeks.

IHME was predicting the virus would magically go away in California with continued shelter in place in the next 3 weeks. They just backed away from this crazy prediction that the data has never fit. However, policymakers depended upon it in making the tradeoff: aggressive policies aimed at control could be justified if they'd really get us to a sustainable containment regime in a couple months.

> And significant portions of the US seem to be giving up on control and going for a herd immunity strategy.

In the end, the only long term paths are to radically change our way of life forever, or herd immunity. There's only really one vaccine effort that could deliver tens of millions of doses to North America by mid-2021, and that's the Johnson & Johnson program. Odds of that program's success are 50-50 at best.