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Updating Herd Immunity Models for the US: Implications for the Covid-19 Response

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Re: Updating Herd Immunity Models for the US: Implications for the Covid-19 Response

#91

Post by gpm »

nradov wrote: post #32

These models are fundamentally flawed in that they assume immunity or susceptibility are binary conditions. Based on recent research it appears a significant fraction of the population has at least limited immunity from prior exposure to other coronaviruses. They can still get infected but the immune system clears it more quickly and they tend to suffer fewer symptoms compared to immunologically naive patients. https…

Every model is wrong, some models are useful. Does this flaw make this model useless? On the flip side is it a useful approximation even if it's not completely accurate?

Re: Updating Herd Immunity Models for the US: Implications for the Covid-19 Response

#92

Post by gpm »

umvi wrote: post #2

So, according to this paper 34.2-47.5% of US citizens need immunity before the pandemic can be declared over? So best case scenario we can achieve herd immunity with roughly 100M infections/recovered. USA is currently at ~8M infections/recovered, so that means we are roughly 8% of the way to herd immunity (best case). At the current rate of +50K infections per day, that's 20 days per 1M infections, so we need 20 days…

200k dead, infection fatality rate estimates seem to vary between 0.1 and 1%, so there should be at least 20m infections.

Re: Updating Herd Immunity Models for the US: Implications for the Covid-19 Response

#93

Post by saalweachter »

Animats wrote: post #84

Whatever happened to large-scale antibody testing? You'd think that someone would be testing a few thousand random people each week to see how many people have been infected to date. That sort of thing was being done in the US back in April.[1][2] But it seems to have stopped. If you're going to talk about "herd immunity", you need that info to get anywhere. [1] https://www.medrxiv.org/content/10.1101/2020.04.14.2006…

There was a recent study of dialysis patients: https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

TLDR: "During the first wave of the COVID-19 pandemic, fewer than 10% of the US adult population formed antibodies against SARS-CoV-2, and fewer than 10% of those with antibodies were diagnosed."

Re: Updating Herd Immunity Models for the US: Implications for the Covid-19 Response

#94

Post by dmurray »

Animats wrote: post #84

Whatever happened to large-scale antibody testing? You'd think that someone would be testing a few thousand random people each week to see how many people have been infected to date. That sort of thing was being done in the US back in April.[1][2] But it seems to have stopped. If you're going to talk about "herd immunity", you need that info to get anywhere. [1] https://www.medrxiv.org/content/10.1101/2020.04.14.2006…

The antibody tests seemed to be consistently underestimating other measures of Covid-19 immunity, even conservative ones, so they're not considered as useful as we thought in April or May.

It's possible the tests aren't sensitive enough, or immunity is largely based on T-cells (more expensive to test for) rather than antibodies [0], or antibodies for other coronaviruses confer some level of immunity, or something else we still don't understand.

[0] https://www.eurekalert.org/pub_releases/2020-08/cp-mcc081720...

Re: Updating Herd Immunity Models for the US: Implications for the Covid-19 Response

#95

Post by matthewdgreen »

orangecat wrote: post #79
matthewdgreen wrote: post #68

Earlier quoted context omitted.

> I certainly haven't observed any significant change in behaviors since the July peak, yet the numbers are falling like a rock regardless. Picking FL as an example: deaths are down only about 50% since the peak in August (7-day averaged), and the numbers are surprisingly "sticky" (in the sense that they're not going down all that quickly.) For the record, FL lost 139 people yesterday; that's nearly the capacity of a…

For the record, FL lost 139 people yesterday 139 deaths were reported; those deaths actually occurred over the last several months. Which means we won't know how many actually died yesterday for a while, but it's likely well below 139. Jennifer Cabrera posts regular updates with dates of deaths, e.g. https://twitter.com/jhaskinscabrera/status/13139124858340884...

You make this out like I've picked on some rare outlier day, but the state has had multiple days in the past two weeks with even bigger death numbers. The 7-day average is a pretty substantial 85. If your point is that the drop since August has been more substantial, then I would need to know that the older, higher numbers were not also subject to the same delays.

https://public.tableau.com/profile/peter.james.walker#!/vizh...

Re: Updating Herd Immunity Models for the US: Implications for the Covid-19 Response

#96

Post by em500 »

rimliu wrote: post #88
hcknwscommenter wrote: post #58

Earlier quoted context omitted.

Because no demographic has been demonstrated to have a 99.99% survival rate?

I think in Italy they had 100% for 10-19 bracket.

In the Netherlands it's 100% for the 0-14 bracket. 1 out of of the 6500 deaths so far was younger than 25 (he was in the 15-19 bracket).

Re: Updating Herd Immunity Models for the US: Implications for the Covid-19 Response

#97

Post by matthewdgreen »

School-Cotton wrote: post #90
matthewdgreen wrote: post #69

Earlier quoted context omitted.

I think the reason that HN, Reddit et al. have this impression is that state policies in conservative states are explicitly less restrictive than those in less conservative states. Florida just removed all stadium event attendance limits, for example. Within any given state there are all kinds of political beliefs and economic situations that may be more or less correlated with spread, but state governance is a very…

Is there any evidence that level of restriction correlates with severity of outbreaks, though?

I mean, this seems to be the basic understanding of every single epidemiologist and public health expert, and also correlates with everything we know about the physical mechanism of how COVID spreads.

Re: Updating Herd Immunity Models for the US: Implications for the Covid-19 Response

#98

Post by neves »

e40 wrote: post #14
umvi wrote: post #2

So, according to this paper 34.2-47.5% of US citizens need immunity before the pandemic can be declared over? So best case scenario we can achieve herd immunity with roughly 100M infections/recovered. USA is currently at ~8M infections/recovered, so that means we are roughly 8% of the way to herd immunity (best case). At the current rate of +50K infections per day, that's 20 days per 1M infections, so we need 20 days…

I wonder if this also means that only 35% of us need a vaccination to declare it over. I had previously read 60-70% were needed and that 35% of Americans get a flu shot. That depressed me. EDIT: seriously, downvoting this comment? Can't imagine why and would like to know.

The vaccine won't be 100% effective. The FDA just approves vaccines that are at least 50% effective, and with the margin of error it's possible that they will work in 30% of the population.

Re: Updating Herd Immunity Models for the US: Implications for the Covid-19 Response

#99

Post by regularfry »

goalieca wrote: post #71
hammock wrote: post #18

Earlier quoted context omitted.

Well, we could get to 2MM faster if we opened everything up for the less-vulnerable populations (i.e. everyone under 50 without obesity or heart conditions) for whom the survival rate is above 99.99%. You might then be looking at 500k a day rather than 50k.

This is roughly what is called for here by some of the leading experts: https://gbdeclaration.org/

These are not "some of the leading experts". https://www.wired.co.uk/article/great-barrington-declaration...

Re: Updating Herd Immunity Models for the US: Implications for the Covid-19 Response

#100

Post by [deleted] »

Animats wrote: post #84

Whatever happened to large-scale antibody testing? You'd think that someone would be testing a few thousand random people each week to see how many people have been infected to date. That sort of thing was being done in the US back in April.[1][2] But it seems to have stopped. If you're going to talk about "herd immunity", you need that info to get anywhere. [1] https://www.medrxiv.org/content/10.1101/2020.04.14.2006…

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