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Re:The disease-induced herd immunity level for Covid-19 is l... by rossdavidh on Saturday May 09, 2020 @02:03PM (#23126956)
Interesting that it seems to suggest there is an optimal amount of distancing/lockdown/etc. to lower the peak, but avoid a big "rebound". I don't see a lot of discussion about how to find that optimum amount.

It has occurred to me that the planet is essentially conducting a gigantic experiment in virus evolution, by creating a novel viral selection environment never seen before. For example, how does it impact a virus if the strains most likely to send the host to the hospital, actually spread more than the strains most likely to be asymptomatic, because even asymptomatic hosts are in isolation?

Unless there is a vaccine or cure coming soon (there isn't), then the end result must be herd immunity, no matter what the policy. It would seem that we should be considering how to select for the healthiest segment of the population to provide that herd immunity, rather than trying to isolate as much as possible in the vain hope that it will die out prior to that point. If that was every possible, it has long since spread way too far to expect that to be possible.

There might be cases (e.g. MERS) where you can stomp out a virus before it spreads enough to cause herd immunity, but we have long since passed that point. I don't think most people (including policy makers) are thinking about the endgame properly (as this paper does).

Re:The disease-induced herd immunity level for Covid-19 is l... by Isinlor on Saturday May 09, 2020 @02:49PM (#23127344)
Currently we need to learn more about this virus to make informed decisions - there is more we still don't know, than we do know for sure. Trying to slowly contain the virus like in South Korea, Taiwan, New Zealand is a strategy worth a shot for most of the western world, unless we learn something dramatic new about it. There is no need for draconian lock downs after exponential spread is stopped, but we do need good track and trace programs, masks etc. There are very high risks associated with Swedish strategy of either killing a lot of people due to bad separation of vulnerable people, destroying health of the big part of the population (see below), or even just failing to reach herd immunity because social distancing, closure of schools, and ban on mass gathering will be good enough to slow down the spread a lot, but bad enough to kill disproportionate amount of people. For example Sweden has many times more deaths than other Nordic Countries, but similar economical outlooks, and the even the idea of reaching herd immunity is uncertain. It may be that other Nordic countries will have soon less or about the same amount of restrictions as Sweden, but many times less deaths.

And regarding the risks, one of the scientists who discovered Ebola [0]:

"Many people think COVID-19 kills 1% of patients, and the rest get away with some flulike symptoms. But the story gets more complicated. Many people will be left with chronic kidney and heart problems. Even their neural system is disrupted. There will be hundreds of thousands of people worldwide, possibly more, who will need treatments such as renal dialysis for the rest of their lives. The more we learn about the coronavirus, the more questions arise. We are learning while we are sailing. That’s why I get so annoyed by the many commentators on the sidelines who, without much insight, criticize the scientists and policymakers trying hard to get the epidemic under control. That’s very unfair."

Also based on Japanese study on around 100 COVID-19 cases from Grand Princess passengers [1] and some 6 divers all with mild cases from Germany [2] around 50 to 80% of people seem to have damage to the lungs visible on CT scans after mild symptomatic or even asymptomatic infection. Two of the divers had significant oxygen deficiency when doing physical exercise after 5-6 weeks of recovery. The guess of the doctor who was inspecting them is that this is permanent damage that may take years to recover if ever.

[0] https://www.sciencemag.org/news/2020/05/finally-virus-got-me...

[1] https://pubs.rsna.org/doi/10.1148/ryct.2020200110

[2] https://translate.google.com/translate?sl=auto&tl=en&u=https...

Re:The disease-induced herd immunity level for Covid-19 is l... by pacala on Saturday May 09, 2020 @03:04PM (#23127459)
I am worried about this disease. I am perhaps even more worried that I can't calibrate how worried I am supposed to be.

Case in point 'There will be hundreds of thousands of people worldwide, possibly more.' Taking 'hundreds of thousands' to be 500,000 and 'number of people worldwide' to be 8,000,000,000, we get 0.006% people with long term adverse side effects. This is much less than 1% we assume are going to outright die. Is this ballpark even remotely accurate? Do we have reliable clinical / epidemiological data to ballpark this number? Do models have any credibility left after being adapted on-the-fly by an order of magnitude or more?

As of the Grand Princess / 6 divers scenarios, something doesn't add up. Either 50% of people [in context, 4 billion] are going to end up with serious long term oxygen deficiency or not. If this is indeed the case, I don't understand why the medical community doesn't explain in more stern terms the severe [Black Death lite] long term implications. Given the implied severity, why don't we have a Manhattan project to replicate these studies, in every single developed country out there? Drop everything else you are doing, pick a 10,000 sized city with a sizeable outbreak and CT everyone in that city, repeatedly. Send the Army if you have to.

Re:The disease-induced herd immunity level for Covid-19 is l... by Isinlor on Saturday May 09, 2020 @04:24PM (#23128016)
I'm part of a community whose whole purpose is to accurately predict future and calibrate based on established track record. Based on what you are saying, you may be interested in that. We normally focus on hacker news type of stuff, but recently we focused a lot on this pandemic due to the impact [0]. As an example of our track record - already in 2017 our best predictors were estimating 36% chance of this type of pandemic by 2026, my personal prediction was also 30%. You should look on our dashboard were we collected a lot of our community predictions here: https://pandemic.metaculus.com/COVID-19/ You can also compare our short term record vs. survey of experts here: https://works.bepress.com/mcandrew/8/

Our current best prediction is that 596 million people will get infected (247M-1.4B 50% CI) before the end of the year and that only 16 million (8.0M-36M 50% CI) will be reported to WHO. We expect also 1.74 million deaths (532k-6.0M 50% CI) world wide before the end of 2020. Overall infection fatality rate is likely to be 0.8% (0.5-1.2 50% CI).

And, I agree with you - we should have had massive projects for track and tracing already in February, but politicians almost everywhere dropped a ball on this besides Taiwan, South Korea maybe Germany and some other countries. In many places there are still no good exit plans.

Also, scientific community is slow to do anything. Masks are good example of that - making a masks at home costs nothing, so if widespread use of homemade masks have a chance to save lives and reduce length of lock downs even by days then the risk-cost-benefit analysis is just overwhelming in favor of widespread mask use. But medical community wants controlled trials and tip-top evidence before trying anything even if it's as simple as a mask.

Overall there seems to be a sort of fog of war going on.

From my perspective the models never had any credibility due to the fact that small errors in model parameters lead to exponentially big errors in predictions. Also, soon after China managed to contain the outbreak it became more or less obvious that human behavior is the biggest unknown in all epidemiological models. No model is able to predict how politicians and society will react.

Here is my comment from 3rd of March [2]: > I think very important part of a model that intends to give real world prediction would be ability to model what happened in China. There needs to be something in the model that allows to slowdown the growth of infection.

Thankfully, big political decisions were never only based on models. They were based on 1. empirical data from SARS outbreaks in China, later on based on China and Italy experiences 2. simple common sense computations like around 20-80% of population can get it if we do nothing (Swine Flu or Spanish Flu) and 0.5-2% of infected can die based on Grand Princess and Chinese data. So the best case scenario assuming no reaction and wide spread like with Swine Flu or Spanish Flu is 0.1% of population dieing and the worst case scenario is 1.6% population dieing. It was obvious that reaction was needed given the severity of the best case scenario with no reaction.

I think what got missed is the fact the people across the world were already starting to react by themselves in early March soon after Lombardy went into lock down. You can see that in Google/Apple Mobility data and in Open Table restaurant reservations. People miss that piece of data even now as lock downs are lifted.

Regarding 50% - this is what shows up on CT scans. The paper does not provide much of interpretation of that scans. But seems like we can indeed expect reduced lung capacity at least soon after recovery in some nontrivial percent of the population. That much we know, the long terms effects are just a guess. I will probably try to make a question to quantify the actual risks, but operationalizating it so that resolution is clear is difficult.

[0] https://pandemic.metaculus.com/COVID-19/

[1] https://www.metaculus.com/questions/247/pandemic-series-a-ma...

[2] https://www.metaculus.com/accounts/profile/103304/#comment-2...

Re:The disease-induced herd immunity level for Covid-19 is l... by pacala on Saturday May 09, 2020 @04:59PM (#23128275)
Thanks for the thoughtful response. Wrt CT scans, the frustration is that we don't know the kind of selection biases led to the respective numbers. It's a couple of studies over non-random populations. 100 cases out of 3,711 passengers; 6 divers out of ??? divers out of 80M people in Germany. We got a couple numbers, how do we responsibly translate them into population-level risk assessments?
Re:The disease-induced herd immunity level for Covid-19 is l... by macintux on Saturday May 09, 2020 @02:26PM (#23127175)
As far as I can tell, there is one big unknown that makes planning particularly difficult: What are the long-term health effects from being infected?

If it turns out that some significant percentage of the population is going to have a negative impact over the course of their lives from this, should we continue to hunker down until a vaccine or better treatments are found?

Re:The disease-induced herd immunity level for Covid-19 is l... by rossdavidh on Sunday May 10, 2020 @09:28PM (#23138011)
From what I'm reading, the best case for a vaccine is 3 years (both development and production on a large enough scale). By which point, it's a moot point because the vaccine will have gotten to herd immunity levels long before that.

In other words, hunkering down won't really change the fact that the vaccine, if it comes at all, won't come in time.

Re:The disease-induced herd immunity level for Covid-19 is l... by ibejoeb on Saturday May 09, 2020 @02:51PM (#23127366)
I can't understand the amount of intrigue surrounding this. It's not some kind of mysterious alien pathogen; there are 6 other coronaviruses that infect humans, and hundreds that infect other animals. There have been numerous outbreaks in the past 20 years. They're very well researched. Still, I'm not holding my breath for a vaccine since these other diseases, like SARS and MERS, are several orders of magnitude more letha.

> some significant percentage of the population is going to have a negative impact

Is there any evidence at all that this is some kind of feature of this disease? It's even starting to look like most people who become infected never even develop the associated disease.

Re:The disease-induced herd immunity level for Covid-19 is l... by mlyle on Saturday May 09, 2020 @03:01PM (#23127433)
This causes a whole lot more people to be hospitalized with severe illness. Severe illness tends to result in morbidity even if you survive.

A fair number of people with SARS-CoV-1 ended up with chronic fatigue ailments, etc, afterwards, too.

We don't know, but there's almost certainly going to be more lasting morbidity from this epidemic than the common cold. If it's a little bit, it doesn't change the calculation much. If 1/4th of those hospitalized develop significant morbidity though, that sucks.

Re:The disease-induced herd immunity level for Covid-19 is l... by ibejoeb on Saturday May 09, 2020 @03:23PM (#23127584)
> This causes a whole lot more people to be hospitalized with severe illness.

Sure. And the other ones kill.

> If 1/4th of those hospitalized develop significant morbidity

Am I wrong, or is it that the overwhelming majority of people who are hospitalized already have a comorbidity? Where does 1/4 come from? Why not 100%?

Re:The disease-induced herd immunity level for Covid-19 is l... by irq11 on Saturday May 09, 2020 @02:44PM (#23127319)
This is not an unknown. We have very good data on outcomes. The media has been diving ever-further into niche stories of bad outcomes in order to drive clicks, but the numbers of cases driving these narratives are vanishingly small.

For the vast majority (>98%) of those who are under 60 and otherwise healthy, this disease is on par with the flu.

Even amongst those who are more vulnerable, the rate of long-term sequelae is low. It’s the people who end up in the ICU who are experiencing the most long-term effects, and those people are a single-digit percentage of a single-digit percentage of those infected.

Re:The disease-induced herd immunity level for Covid-19 is l... by macintux on Saturday May 09, 2020 @03:43PM (#23127734)
Quote from a virologist who caught it:

> Many people think COVID-19 kills 1% of patients, and the rest get away with some flulike symptoms. But the story gets more complicated. Many people will be left with chronic kidney and heart problems. Even their neural system is disrupted. There will be hundreds of thousands of people worldwide, possibly more, who will need treatments such as renal dialysis for the rest of their lives. The more we learn about the coronavirus, the more questions arise. We are learning while we are sailing. That’s why I get so annoyed by the many commentators on the sidelines who, without much insight, criticize the scientists and policymakers trying hard to get the epidemic under control. That’s very unfair.

https://www.sciencemag.org/news/2020/05/finally-virus-got-me...

Re:The disease-induced herd immunity level for Covid-19 is l... by irq11 on Sunday May 10, 2020 @01:28AM (#23130518)
Yeah, I read that anecdote, too. Saying “many people” is meaningless. A tenth of a percent of a million people is a thousand people. That’s “many people”, but the rate is quite low.

Facts: in the US, the hospitalization rate for covid is around 4.6 per 100,000. It’s half that for people under age 50. The rate of serious disease is very, very low...and this includes high-risk groups:

https://www.cdc.gov/mmwr/volumes/69/wr/mm6915e3.htm

Re:The disease-induced herd immunity level for Covid-19 is l... by macintux on Saturday May 09, 2020 @02:46PM (#23127332)
This disease has been here for 6 months. The degree of certainty in your assessment seems unwarranted.

I want to believe it, but optimism and certainty given the novelty of this virus seem strange bedfellows.

Re:The disease-induced herd immunity level for Covid-19 is l... by xamuel on Saturday May 09, 2020 @02:56PM (#23127395)
As rossdavidh correctly pointed out, if we don't get a vaccine soon (which we probably won't), then herd immunity is virtually the only way out anyway. Even if it turns out there are long term health problems, that doesn't really change that calculus. Very few people can completely isolate themselves indefinitely (remember, the virus doesn't just magically not spread in supermarkets), and if everyone did that, most of us would starve and the few who didn't starve would inherit a post-civilization ruin.
Re:The disease-induced herd immunity level for Covid-19 is l... by mlyle on Saturday May 09, 2020 @03:07PM (#23127481)
It does change the economic break even point a little bit. If intervention A reduces infection count 10% in the time to a vaccine, whether it's worth it depends upon whether it prevents 20,000 deaths, or 20,000 deaths and 40,000 long term illnesses.

The threshold to herd immunity depends upon contact rate. So interventions well short of "lockdown" may not completely prevent the spread of the virus but still reach equilibrium at a lower number of people infected.

Re:The disease-induced herd immunity level for Covid-19 is l... by xamuel on Saturday May 09, 2020 @03:14PM (#23127526)
You're right, the question of where the break even point is is quite complex. Aside from the numbers you posted, it also depends on the economic side effects of "intervention A": better to be one of the 40,000 with long-term illnesses in a functional society, than to avoid the long-term illnesses but live in a non-functional society because we destroyed the whole economy.
Re:The disease-induced herd immunity level for Covid-19 is l... by macintux on Saturday May 09, 2020 @03:27PM (#23127609)
The economy is a human construct, subject to redefinition if needed. It’s not some inevitable product of the natural world.

Sacrificing lives unnecessarily to “save the economy” is perverse in that the economy is supposed to serve us, not the other way around.

I’m not saying we should stay in lockdown forever, but I’d rather our leaders think creatively with a default view of “let’s be cautious with a global pandemic that has so far shown great destructive powers when left unchecked”.

Re:The disease-induced herd immunity level for Covid-19 is l... by xamuel on Saturday May 09, 2020 @03:43PM (#23127727)
There's this boogeyman floating around that "the economy" consists of a bunch of billionaires drawing lines on charts, drinking champagne and laughing at the proles. If any of that is going on and is costing lives, by all means, put an end to it.

But when I talk about "the economy", I mean the process that puts food on plates and electricity in houses. Someone has to grow the food, someone has to transport it, someone has to store it, distribute it. Sure, we could round up the world's billionaires and force them to do that, but unfortunately there aren't enough of them to do it for everyone, so someone else will have to do it too. And someone will have to service the cars and trains those workers take to get to work, and someone will have to watch their kids, and someone will have to provide toys to the people watching their kids, etc. etc. etc. THAT'S what I mean by "the economy".

Re:The disease-induced herd immunity level for Covid-19 is l... by ibejoeb on Saturday May 09, 2020 @03:44PM (#23127737)
You are completely ignoring the knock-on effects of this experiment, like driving an enormous population into destitution and fostering crime and violence.

Fewer than 300,000 people have died with nexus to Covid. Even if that population were to double, we're left with 0.0066% chance of death. It's great to be legitimately concerned, but those are good odds as far as I'm concerned.

What's an acceptable risk for you?

Re:The disease-induced herd immunity level for Covid-19 is l... by macintux on Saturday May 09, 2020 @08:22PM (#23129321)
WWII, the country came together, dealt with rationing for years. The draft and rationing forced everyone to sacrifice.

This disease has the potential to kill 3 million Americans, 70 million people globally, and that’s only if we spread it out.

Why aren’t we all sacrificing so that the poorest, most vulnerable population can have sufficient funding so that they will have a roof and food and clothing? Why isn’t the federal government sending monthly checks? Where’s my tax increase? Where’s why aren’t I being drafted to work in health care or food delivery?

All our government has asked of us, begrudgingly, is to stay inside for a while, and we can’t even do that without whining.

Re:The disease-induced herd immunity level for Covid-19 is l... by mlyle on Sunday May 10, 2020 @12:18PM (#23133764)
> This disease has the potential to kill 3 million Americans

This is looking less and less likely. With increasing evidence that the infection fatality rate is 0.6%, and that the herd immunity threshold may be somewhere around 30% infected, it's more like 700k. Still catastrophe, but 1/4th the catastrophe you imply...

> All our government has asked of us, begrudgingly, is to stay inside for a while, and we can’t even do that without whining.

I favored sheltering before everyone else. It was a good way to blunt the incident wave of the epidemic and prevent health care overload.

At this point, Rt with the current intervention isn't low enough to ever get us to a regime of extreme containment in any reasonable/attainable amount of time, and there's too many jurisdictions that are hotbeds of the virus that will just reintroduce it. I am not convinced that the current strategy saves lives in the long term.

It even risks backing us into a corner, where we have no choice but to reopen more than we'd like, and then face a devastating fall season with little population immunity and no seasonal factors on our side. Especially in locations like the SF Bay Area, under the nation's strictest health order but also with a very low per capita case load.

Worse, it's hard to be sure the intervention is even effective. Looking at data series on https://rt.live , there's no obvious inflection or discontinuity relating to sheltering or relaxing of sheltering in the individual states' series. Rt was falling before sheltering, and continued to fall at a comparable rate afterwards...

Re:The disease-induced herd immunity level for Covid-19 is l... by ibejoeb on Saturday May 09, 2020 @03:31PM (#23127632)
Where did everyone get the idea that isolation was meant to reduce the overall number of infections?
Re:The disease-induced herd immunity level for Covid-19 is l... by mlyle on Sunday May 10, 2020 @12:21PM (#23133791)
Uh, reducing transmission does prevent drastic overshoot past the herd immunity threshold, so it does affect the area under the curve a bit-- not just flatten it.
Re:The disease-induced herd immunity level for Covid-19 is l... by lisper on Saturday May 09, 2020 @02:51PM (#23127370)
> We have very good data on outcomes

Not long-term outcomes. (And even short-term our data is not "very good" because we still have no idea what the actual infection rate is.)

Re:The disease-induced herd immunity level for Covid-19 is l... by jakeogh on Saturday May 09, 2020 @02:08PM (#23127016)
Senegal is worth looking at (end of vid): https://youtu.be/iBma_0oAiMI