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

#111

Post by xadhominemx » Thu, Oct 08, 2020, 9:23 PM UTC

timr wrote: post #35

Gabriela Gomes was one of the first epidemiologists making this observation (as far back as May), and has found even lower thresholds (10-20%): https://www.medrxiv.org/content/10.1101/2020.04.27.20081893v... https://www.medrxiv.org/content/10.1101/2020.07.23.20160762v... https://www.medrxiv.org/content/10.1101/2020.09.26.20202267v...

Well 20% of NYC had COVID and we are currently seeing outbreaks in communities that have relaxed social distancing measures, so it seems obvious that her calculations are incorrect.

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

#112

Post by stormbrew » Thu, Oct 08, 2020, 9:34 PM UTC

just-juan-post wrote: post #27

jupp0r wrote: post #15

Keep in mind that "herd immunity" isn't really immunity, it's the point at which Rt (the average number of people each infected person passes the infection on to) drops below 1.0 and the spread shrinks instead of growing. Rt is dependent on how people behave. When behavior changes, Rt can change as well. Each herd immunity level is thus dependent on health measures, which is why "reaching" herd immunity and then loos…

> Each herd immunity level is thus dependent on health measures This seems like something you made up. Can you cite your source? How exactly does your rule apply to non-humans? What "health measures" do packs of wild horses take when disease comes to the herd?

It doesn't apply to non-humans because herd immunity is not something that is at all related to non-human populations. The term was coined to describe a trait of human populations and was found to be difficult if not impossible to achieve in humans until we started to vaccinate.

https://en.wikipedia.org/wiki/Herd_immunity#History

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

#113

Post by maxerickson » Thu, Oct 08, 2020, 9:35 PM UTC

war1025 wrote: post #51

watwut wrote: post #47

Earlier quoted context omitted.

> Also I've lost faith in the "we're not doing enough testing" argument since we went and tried to get tested and they turned us away. That does not imply that there is enough testing. That just implies that your doctor or health care system is unwilling to test someone in your circumstances. "Not doing enough testing" is not referring to just test kids not being available, it is also referring to health system polic…

I guess to clarify, it has been my impression that the healthcare industry are the people telling us we are not doing enough testing. We attempted to get tested and they said no, not worth the bother. That seems contradictory to me.

Healthcare is not a monolithic entity, so different parts of it saying different things is coherent. It probably isn't the case, but it could even be that doctor deciding the test wasn't worth doing.

It can also be the case that insufficient testing is available in your area.

I know a group of people that were tested because of potential exposure (they were tested based on 1 person reporting symptoms; the additional tests were done prior to that result coming back).

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

#114

Post by sfblah » Thu, Oct 08, 2020, 9:52 PM UTC

xadhominemx wrote: post #109

hammock wrote: post #75

Earlier quoted context omitted.

>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.

Who is suggesting 100% of the population be under close quarantine? We haven’t seen anything like that since April.

Bay area resident here. My kids can't go to school. I barely go to the store. Even going for a walk is tricky, as unless you take massive precautions (which I'm fine with, btw) everyone yells at you. I basically have no human contact outside my family, and it's been like this for six months. So, yeah, for me the situation couldn't really get much more quarantined.

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

#115

Post by sfblah » Thu, Oct 08, 2020, 9:54 PM UTC

arrrg wrote: post #81

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…

Deaths are probably more instructive – just to get a ballpark number. If only because deaths are less likely to overlook too many people. If the IFR is around 1% we would expect around 1,000,000 deaths if one third of Americans have to be infected for herd immunity. So that would suggest the US is 20 percent of the way there. Given the haphazard way of calculating these numbers I would, however, put huge error bars a…

I agree strongly with this type of analysis. The data we're seeing is strongly skewed by all kinds of biases. Looking at deaths at least removes one big piece of bias.

I too suspect areas are achieving some limited herd immunity. I don't think the behavioral changes adopted in the US have done much. Mostly, I just think less social people aren't getting it. More social people are.

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

#116

Post by sfblah » Thu, Oct 08, 2020, 9:56 PM UTC

rst wrote: post #80

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

So, maybe that means by slowing the infection, what we're really doing is ensuring a neverending slow wave of infections ... forever? Maybe what normally happens with these kinds of viruses is they infect everyone then die out? And if you slow that, they never die out?

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

#117

Post by guscost » Thu, Oct 08, 2020, 9:59 PM UTC

meowzero wrote: post #101

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.

That is a good strategy. Unfortunately, ppl with survival rate above 99.99% might live with more vulnerable population. It'll be difficult to figure out how to effectively quarantine the more vulnerable population away from the less-vulnerable.

Why not allow healthy people to inoculate with a reasonable dose of the virus so they can control the timing, and then self-quarantine? I would have done that months ago if it was allowed. Even if it only has a partial chance of conferring immunity, doing that would have helped fewer vulnerable people get sick, but instead public health authorities are still clinging to “informed consent” nonsense, as if turning the world upside-down isn’t another serious risk to mitigate.

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

#118

Post by jjgreen » Thu, Oct 08, 2020, 10:06 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…

    Our language gets more and more influenced by USA "English" usage,

That's a two-way street https://notoneoffbritishisms.com/

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

#119

Post by tzs » Thu, Oct 08, 2020, 10:21 PM UTC

Buttons840 wrote: post #83

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…

Aren't flu shots usually free? The last few I've gotten were.

Flu shots are covered by insurance without a copay or coinsurance in the US, but there are about 30 million people who do not have health insurance.

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

#120

Post by mcguire » Thu, Oct 08, 2020, 10:28 PM UTC

sfblah wrote: post #114

xadhominemx wrote: post #109

Earlier quoted context omitted.

Who is suggesting 100% of the population be under close quarantine? We haven’t seen anything like that since April.

Bay area resident here. My kids can't go to school. I barely go to the store. Even going for a walk is tricky, as unless you take massive precautions (which I'm fine with, btw) everyone yells at you. I basically have no human contact outside my family, and it's been like this for six months. So, yeah, for me the situation couldn't really get much more quarantined.

The Bay area sounds excessive, but consider that under the ancestor's idea, you couldn't do that if you were concerned with reducing your risk of infection.

I'm 53. I have asthma and I really hate hospitals. Right now, I have been going for groceries about once a week. I've gone to some appointments, but I've cancelled others. I've been getting take-out some, and I even went on one shopping expedition for craft supplies. I'm relatively comfortable with that because, while I have to assume everyone else is potentially infected, I can also assume that most of them are taking steps to protect me---a mask is significantly more effective at preventing spread from someone infected than it is at preventing an infection of the wearer.

Close quarantine means no going to the store at all. Not going for walks. It specifically means no human contact outside the people you are quarantined with.