Updating Herd Immunity Models for the US: Implications for the Covid-19 Response • Hacker News Board

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

#71

Post by goalieca » Thu, Oct 08, 2020, 5:35 PM UTC

hammock wrote: post #18

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…

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/

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

#72

Post by learc83 » Thu, Oct 08, 2020, 5:36 PM UTC

AstralStorm wrote: post #66

learc83 wrote: post #37

Earlier quoted context omitted.

>My child had a fever a few weeks ago, it was an ORDEAL finding a place to get him tested. You have to be quite motivated. That's because the test won't change anything. If it's positive, they'll tell you to isolate your kid. If it's negative, there's a high enough false negative rate that you'll still need to basically treat them like they have COVID (stay home and isolate).

Incorrect. Not being treated early is likely a main factor between likelihood of medium to severe.vs no to mild symptoms, beyond immunity. And isolation of sick patient from viral reservoir (such as fomites and other asymptomatic sick) is known to be important too, as it changes the viral inoculum dose.

Normal healthy children who don't develop a severe case aren't treated at all, so talking about early treatment is irrelevant. I literally just talked about this with a close family member who is a Children's ER doctor.

>And isolation of sick patient from viral reservoir (such as fomites and other asymptomatic sick) is known to be important too, as it changes the viral inoculum dose.

This isn't known to be important. If a person has been infected long enough that they are already symptomatic then "viral inoculum dose" is irrelevant.

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

#73

Post by dragonwriter » Thu, Oct 08, 2020, 5:42 PM UTC

tzs wrote: post #70

e40 wrote: post #14

Earlier quoted context omitted.

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.

I don't understand why more people do not get flu shots, unless they have no medical insurance and cannot afford the cost. It's not always effective, because they have to predict when they make it what strains of flu will be prevalent in the next flu season, and they don't always get that right, but in that case you are no worse off than if you had not gotten the vaccine. But when they do get it right, it can save yo…

> With a COVID vaccine, I doubt it will get anywhere near the same fraction of takers as the flu vaccine.

It will if closures are lifted but vaccination is made a requirement (either privately or by government mandate) for on-site work, schooling, etc. The flu vaccine is treated as primarily a personal preventive medical treatment; while it is encouraged for public as well as personal health reasons, there is no force put behind it. But it is quite possible, and there is plenty of precedent for, public health measures to be mandated (especially a conditional mandate, like for schools, work in particular conditions--including any public content or even on-premises work) and enforced.

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

#74

Post by mikelward » Thu, Oct 08, 2020, 6:15 PM UTC

pbhjpbhj wrote: post #55

bigbubba wrote: post #39

Earlier quoted context omitted.

(People scribble on cigarette packages? Aren't those waxed cardboard or something? I wouldn't expect a pen to work well on those.)

FWIW they almost certainly didn't write on a cigarette package in this instance ;o) It's just the name of that type of maths because people used to use whatever small, available, piece of paper was around - so cigarette packs some time ago (you definitely could write on them with a ballpoint pen (ie un bic ). Getting tangential, napkins to me in the UK have always been cloth, and we have serviettes (a French word, me…

I can't decide whether to use the term cutlery (mainly UK) or silverware (mainly US). They're both inaccurate, especially when asking for plastic/disposable versions.

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

#75

Post by hammock » Thu, Oct 08, 2020, 6:27 PM UTC

mcguire wrote: post #64

hammock wrote: post #23

Earlier quoted context omitted.

Why the massive downvotes?

Are you seriously suggesting we lock over 110,000,000 people (34% of the population) in close quarantine for the duration? How do you plan to feed them? Get them medical care (be sure you don't overwhelm the system with the under 50s that get sick)? Keep them from rioting against their captors? What happens when you decide it's good enough and release them, and the residual infection sweeps through that population li…

>Are you seriously suggesting we lock over 110,000,000 people (34% of the population) in close quarantine for the duration?

As opposed to 100% of the population? It sounds like an improvement to me. I'm suggesting relaxing restrictions for a part of the population, not increasing them.

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

#76

Post by alkonaut » Thu, Oct 08, 2020, 6:30 PM UTC

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.

No, immunity through vaccination is less heterogeneous and more random.

With natural infection, the socially active will be infected and removed first, which lowers the fraction needed.

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

#77

Post by tzs » Thu, Oct 08, 2020, 6:33 PM UTC

dragonwriter wrote: post #73

tzs wrote: post #70

Earlier quoted context omitted.

I don't understand why more people do not get flu shots, unless they have no medical insurance and cannot afford the cost. It's not always effective, because they have to predict when they make it what strains of flu will be prevalent in the next flu season, and they don't always get that right, but in that case you are no worse off than if you had not gotten the vaccine. But when they do get it right, it can save yo…

> With a COVID vaccine, I doubt it will get anywhere near the same fraction of takers as the flu vaccine. It will if closures are lifted but vaccination is made a requirement (either privately or by government mandate) for on-site work, schooling, etc. The flu vaccine is treated as primarily a personal preventive medical treatment; while it is encouraged for public as well as personal health reasons, there is no forc…

45 states allow skipping their conditional mandate for schools if the parents cite religious objections. I expect their COVID mandates will have similar exceptions.

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

#78

Post by rossdavidh » Thu, Oct 08, 2020, 6:40 PM UTC

streptomycin wrote: post #22

https://www.medrxiv.org/content/10.1101/2020.07.23.20160762v... was a similar study a couple months ago that estimated 10-20%, rather than the 34.2-47.5% in this paper. The bigger question is how long immunity lasts, which is still not known.

Tests this year on blood from people who had SARS in 2003, indicated that 17 years later they still had T-cell responses . On the other hand, coronaviruses which are experienced as "colds" apparently have a lot less retention of immune system recognition. Optimistic scenario is that the immune system is "smart" enough to recognize which infections are a big deal which must be remembered forever, and which are not. Pessimistic scenario is we got lucky with SARS, and may not with Covid-19.

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

#79

Post by orangecat » Thu, Oct 08, 2020, 6:50 PM UTC

matthewdgreen wrote: post #68

StevePerkins wrote: post #6

Earlier quoted context omitted.

> USA is currently at ~8M infections/recovered CONFIRMED cases. The total number of cases is probably 5-10x that. I live in the Deep South, and honestly I suspect that our curves have fallen simply due to a "limited" herd immunity effect (i.e. the groups of people most likely to catch COVID have already done so in large enough numbers). I certainly haven't observed any significant change in behaviors since the July p…

> 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...

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

#80

Post by rst » Thu, Oct 08, 2020, 6:53 PM UTC

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…

This also assumes that acquired immunity from an infection is complete and permanent. Immunity to other coronaviruses decays over a year or two -- meaning that before the five years are up in your scenario, there would be a significant cohort of prior victims open to reinfection.

See, e.g., https://www.nature.com/articles/s41591-020-1083-1