The disease-induced herd immunity level for Covid-19 is lower than the classical
arxiv.org
arxiv.org
The duration of immunity for other corinaviruses varies quite a bit, the disease has the potential to cause permanent respiratory damage, with uncertain consequences for the possibility of reinfection, and we’re still seeing novel symptoms arise as in the case of the children with Kawasaki-like inflammation in NYC.
I get the strong desire to return to a normal state of affairs, but paving over reality with scientific notions, deployed pseudoscientifically, does very little to get us there.
How do we “know” either of those facts? You may well be right, but I don’t see a scientific consensus yet.
https://www.technologyreview.com/2020/04/27/1000569/how-long...
Nowhere is this stated or suggested. Why are you saying that it is? The only point it makes (contrary to all your claims) is we don’t know the duration of immunity and the situation is unpredictable, based on what we know of other coronaviruses. From the article:
>What I have been telling everyone—and no one believes me, but it’s true—is we get coronaviruses every winter even though we’re seroconverted,” says Matthew Frieman, who studies the virus family at the University of Maryland. That is, even though most people have previously developed antibodies to them, they get the viruses again. “We really don’t understand whether it is a change in the virus over time or antibodies that don’t protect from infection,” he says.
> After testing different scenarios, the Harvard group concluded that their projections of how many people end up getting covid-19 in the coming years depended “most crucially” on “the extent of population immunity, whether immunity wanes, and at what rate.” In other words, the critical factor in projecting the path of the outbreak is also a total unknown.
The figure for immunity duration at say 95th percentile seems to be the key figure for herd immunity being viable or not, at least to my layman eyes.
Please stop adding certainty where it is unwarranted. Either supply citations to expert authorities, or be quiet. Otherwise you're just spreading misinformation.
It seems to me that you're right, we can't know for certain until many years later, but in the meantime the world goes on, we can't all just cryogenically freeze ourselves. The best we can do is make educated guesses based on previously existing coronaviruses.
I’m not sure why people can’t seem to fathom that we are still very early in our understanding and experience of this disease, no matter how dramatic its consequences thus far. There’s no way to accelerate things through false confidence or other forms of denialism.
Has anyone here done the research that we can use as a reasonable prior? My assumption was those diseases all produce long lasting antibodies.
https://www.technologyreview.com/2020/04/27/1000569/how-long...
There's also no way to decelerate things through false humility. We're in an urgent crisis, so we must make decisions now based on whatever evidence is available; there's no position of safety we can retreat to while waiting to learn more.
[1] https://www.businessinsider.com/coronavirus-fauci-those-who-...
Also, FWIW, if getting the actual disease doesn't generate sufficient antibodies to confer immunity, being dosed with a vaccine wouldn't either. Whether vaccine-supported or not, herd immunity is the most likely outcome (unless the disease becomes endemic instead). What remains to be seen is how many people have to get ill to get there.
Is it outrageous to think R0 could be 3.5 in NYC but 1.5 somewhere else?
No, not at all. It would be outrageous to think that it doesn't vary by a factor of two IMO.
How do you use this in places where transmission is less than 1? New Zealand now has a transmission rate considerably under 1, but this seems to break the calculation.
Does this mean that a reproduction number under 1 doesn’t need herd immunity? We do, because we can’t stay locked down indefinitely, and presumably our rate will go up when we relax restrictions.
What is that again?
It does indicate the Swedish model could work, because the paper says it's just 43% with "disease-induced" herd immunity. And according to Swedish authorities 25% of Stockholm population already has antibodies.
Being a resident Swede, my lasting impression is that the so-called "strategy" has two legs (can be backed by a long list of official statements) 1: hope that the virus does not hit, and if it does, that it is not necessary to do anything and/or it is already too late anyway and that hopefully it will disappear through herd immunity. A hope that has been expressed up to twice weekly for the last 2 months or so, while the number of deaths go up and up. And 2: in a manner typical of governmental agencies everywhere: never ever admit to any mistake or error in judgement. Like admitting that the recommendation for the public not to use face masks was wrong, and was brought on by secondary concerns (over availability in hospitals). Even now (as of yesterday) the official stance is that using face masks might increase risks and efficacy is not backed by "scientific proof".
The paper should probably be seen in this light. The main author of the paper Tom Britton forms together with Giesecke and Tegnell the "herd immunity" triumvirate that is responsible for the Swedish mess that currently renders Sweden a place among the top 10 countries with most fatalities per million. At the face of it this paper just seems to confirm that protective measures actually work. But by shining the light the herd immunity aspect of the equation he makes it sound like they were right all along.
[0] https://mackuba.eu/corona/#compare?val=d&align100=1&pop=1&c=...
Herd immunity is horrible word, and none wants to use it anymore. But because flattening the curve does leave the virus linging around, it in many practies is same as "flatten the curve" as pointed by epidemologists:
> The "Flatten The Curve" plan was touted by every public health organization, while the United Kingdom's original "herd immunity" plan was universally booed. They were the same plan. The UK just communicated theirs poorly.
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).
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...
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.
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...
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?
In other words, hunkering down won't really change the fact that the vaccine, if it comes at all, won't come in time.
> 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.
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.
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%?
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.
> 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...
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:
I want to believe it, but optimism and certainty given the novelty of this virus seem strange bedfellows.
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.
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”.
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".
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?
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.
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...
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.)
Meaning, let the young and stupid go out and play, it will allow for herd immunity at a lower rate than the typical randomly distributed rate.