Stephen Davies on Optimal Responses to the Coronavirus
The biology of this particular virus means we have already passed the point where lockdowns and measures of that kind can resolve the situation. If that strategy is followed you will delay the evolution of the virus into a milder form and when it returns (as it will, because it is now established in a reservoir of people around the world) the effect will be as bad as it was the first time or even worse because of the disruption caused to systems by the first wave. There are literally hundreds of cases in history that historians have studied where that strategy was followed, always with that result if the pathogen was sufficiently infectious to have spread to a large part of the planet’s surface. People will self isolate but if they do too much that will be bad because it will stop the virus spreading through the population. What you want is for as much of the population as possible to be exposed to the pathogen but in a spread out fashion so there isn’t a huge peak that has all kinds of bad systemic and social effects. You want the pathogen to spread widely so as to speed up its evolution and to speed up the population’s acquiring of resistance. If the spontaneous response of individuals was to self-isolate to the degree that that doesn’t happen then that is very bad news because it means that the pandemic will be more long lasting and will have much bigger effects because of repeated waves. What that leads to eventually, inter alia, is flight as people try to flee the infection which is the last thing you want. This is a case where being rational at the individual level does not produce a benevolent aggregate outcome. There is not one single case in history where spontaneous social isolation has successfully contained an epidemic.
This is from a Facebook comment by Stephen Davies, the Head of Education at the Institute of Economic Affairs in London. Stephen gave me permission to post.
I’m not enough of an historian or epidemiologist to know whether this is right. It just sounds reasonable. And I’ve read enough of Stephen’s work to know how careful and thoughtful a thinker he is generally.
My wife and I have been “socially distancing.” That’s easy for us to do: I rent an office in downtown Monterey and there is little traffic in the hallway and my wife is a free-lance editor who works out of our home. We also went out to lunch every Saturday and we didn’t do that yesterday. But maybe the optimum is for some of us to go out. I thought I was doing the right thing and now I’m not so sure.
Mar 15 2020 at 11:28am
If you are over 60 you should definitely be keeping to yourself because you are in a high risk group. Also, you do want social distancing so as to slow down the spread because otherwise the spread will be very rapid and the health services will be overwhelmed (which is what happened in 1919). The thing to aim for, which is tricky, is to allow the virus to spread through enough of the population to get herd immunity but in a slower fashion so that there isn’t a short intense epidemic with a high peak of cases. So you don’t want strict containment or total lockdown. This can work for a while (as China shows) but you will be storing up trouble for later because the virus is still there, there isn’t herd immunity, and it hasn’t yet evolved into a milder form. Strict containment only works if you can confine the outbreak to geographically specific places and we lost that battle by early February. So the balance to aim for is social distancing but not a complete cessation of contact and activity on the part of society in general. The elderly and other at risk groups should be much more rigorous. What would be helpful is much more widespread testing.
Mar 15 2020 at 11:46am
Thanks, Steve. I’ve been reading the over 60 thing a lot.
Here’s what I wonder: My wife is 70.5 and I’m 69.25 years old. We, especially I, are in good health. Neither of us has ever had any lung problems. Is there really a strong case for our isolating?
Mar 15 2020 at 12:40pm
In this context, age is a proxy for health.
Ageing and health
At the biological level, ageing results from the impact of the accumulation of a wide variety of molecular and cellular damage over time. This leads to a gradual decrease in physical and mental capacity, a growing risk of disease, and ultimately, death. But these changes are neither linear nor consistent, and they are only loosely associated with a person’s age in years. While some 70 year-olds enjoy extremely good health and functioning, other 70 year-olds are frail and require significant help from others.
Mar 15 2020 at 3:32pm
The evidence seems pretty unequivocal…the older you are, the more you careful you should be not to contract the virus:
Even if the risk of your dying was, say, “only” 3%, and your wife, say, “only” 2%, then if you both were infected, there would be about a 5% chance of one of you dying.
Mar 16 2020 at 9:39am
Thanks, Mark and Speed.
Mar 15 2020 at 1:44pm
Question for Steve Davies:
I’m curious about this argument:
The East Asian solution of reducing cases to a low level can hold for 12 to 18 months, by which time we’ll likely have a vaccine.
I can see three possible flaws:
It won’t be possible to hold it down that long.
The things you must do to make that work will tank the economy.
A vaccine is unlikely within 18 months
Mar 15 2020 at 4:21pm
“A vaccine is unlikely within 18 months”
Vaccine candidates have been identified and there are some big players who will be part of this. There are two major problems. The first is that some of the newer technologies involving mRNA or DNA based vaccines have little or no track record in human use. We have no idea about the whether these will be safe and potent. There is good data from the military’s Zika vaccine efforts that some technologies can be rapidly developed and do lead to high levels of neutralizing antibodies. However, one wants a synthetic antigen platform so that large scale cultures of virus, followed by inactivation are not required. This is the current process for seasonal flu vaccine which is old line technology, cumbersome (involves lots and lots of eggs), and time consuming.
The second issue, and perhaps more important, concerns manufacturing at a huge scale and how safe the vaccine is. Since COVID-19 infections are mostly mild, is it prudent to vaccinate everyone? If that is the decision, a relatively small adverse event can be strongly multiplied (great example are the higher levels of Guillame-Barre Syndrome following the swine flu vaccine “experiment” in the late 1970s). Alternatively, only at risk individuals might be vaccinated with the assumption that the rest will only have mild symptoms. It is a complicated call.
One final point, I’m unsure whether there are any animal models for COVID-19. This makes safety and potency testing far more difficult and perhaps in a sense impossible, leading to an ethical dilemma about whether to administer such a vaccine largely. It may be that for this virus we have to rely on small scale testing in humans to make that call.
Mar 16 2020 at 12:30pm
Toward the end of your post, you say, “One final point, I’m unsure whether there are any animal models for COVID-19. This makes safety and potency testing far more difficult . . . ”
My ignorance extends to “just exactly what is an ‘animal model'”, but; Didn’t this jump from pangolins (who may have gotten it from bats). So couldn’t we test on them? Pangolins are endangered, so getting enough to test on might be difficult. But bats are plentiful — unless perhaps the ones susceptible to this are somehow peculiar.
Mar 15 2020 at 6:10pm
Scott the problem with the total lockdown policy is that it won’t stop the spread for long enough. We are most probably 12 months at least away from having an effective vaccine (most estimates are 18 months) while the maximum time suppression through total lockdown will work is a few months and the virus is almost certain to come back in the Autumn. So unless it has a pattern quite different to most viral epidemics we are looking at a big second wave in the Fall and Winter. That’s too soon. The big problem is that the virus can no longer be contained geographically as it is literally all over the world now and has been since late January
Mar 16 2020 at 3:52pm
China currently has near zero community transmission (zero outside Wuhan) and quarantines all new arrivals for 14 days. The economy is picking up. Maybe that’s not sustainable, but I’m not exactly sure why. Ditto for other East Asian countries.
It seems to me that changes in behavior to reduce R0 combined with widespread testing and sharply reduced global travel might be able to buy enough time to get to a vaccine.
Mar 15 2020 at 3:34pm
“The thing to aim for, which is tricky, is to allow the virus to spread through enough of the population to get herd immunity but in a slower fashion so that there isn’t a short intense epidemic with a high peak of cases.”
How likely is it that we can fine-tune the trajectory? And, also, fine-tune the exposure so as to avoid infecting seniors and others with frail health while infecting those for whom infection will not be fatal so as to gain herd immunity? And, doesn’t the “optimal” trajectory, assuming we can achieve it, depend on when a vaccine is likely to emerge and on how treatment capacity will evolve in the future? For example, if we get a vaccine next year, then wouldn’t that argue for trying to delay infection this year so more people can gain immunity through vaccination rather than through infection? Also, will our capacity to treat severe cases increase in the future when the virus returns because we will have been given more time to acquire more ICU space, ventillators, etc.? What is the most *robust* strategy, robust to imperfect coordination of 325M people, robust to imperfect ability to fine-tune who gets infected and when, and robust to understanding that future conditions (available vaccines, hospital capacity, etc.) are likely to be more favorable than present ones?
Mar 15 2020 at 6:11pm
Yes, this is my concern. The same CDC and FDA bureaucrats that have totally screwed up the process of making tests available can be trusted to fine-tune containment measures to get exactly the right amount of spread to avoid overloading ICUs while building herd immunity? And how would they do that with no testing? (As of Saturday, only 475 people had been tested in the entire state of Massachusetts.)
With exponential spread, a slight bit of extra exposure could easily lead to a large number of cases that would overload the healthcare system. It seems far safer to err on the side of reducing exposure, at least until we have much better monitoring in place.
Mar 15 2020 at 11:41am
Maybe the young and the middle-aged ought to expose themselves, for the good of humanity. But the virus is so much more deadly for the elderly that, probably, they should self-isolate.
Mar 15 2020 at 1:06pm
Why phrase this as altruism, when it can just as easily be rationally selfish to take the higher risk v reward route that younger people naturally take in all matters?
No centrally planned recommendations should be followed in (or imposed on) all cases. Anyone convinced that free market economics find feasible solutions at fairly-distributed costs should respect that every actor has to solve for their unique local conditions.
Mar 15 2020 at 1:32pm
Thank you for this post, What would be the suggested readings on these historical episodes, as well as on the alleged tendency of widespread viruses to evolve into milder forms? Stéphane
Mar 16 2020 at 12:06pm
A quite readable explanation of why viruses will evolve toward lower lethality is in this February 21 blog of Matt Ridley’s. The relevant two paragraphs are just below the bat photo. http://www.mattridley.co.uk/blog/coronavirus-bats/
Mar 16 2020 at 12:38pm
Thanks, Fred. The end of the Ridley article is the best news I’ve read in a while.
Apr 9 2020 at 3:16am
no bats but robins are ok?
Mar 15 2020 at 1:52pm
Delay in our current circumstances has more benefits than it did in the historical episodes.
Delay now gives us the opportunity to do things such as make more respirators, develop antibody treatments (google “antibody treatment covid-19” to get a hint as to how much may be accomplished and how quickly), and develop vaccines.
Mar 15 2020 at 2:23pm
The ‘purchasing power of time’ increases with increased liberty and increased population. Coordination of error into central plans and generic recommendations decreases liberty and discourages the application of individual choice.
It’s fascinating to observe the distributed forces of humans’ immune response building the Great Wall against this bioweapon. But I’d compare our hospitals’ dilemma to that of New Orleans or Bangkok during a huge upstream rainy season. What would a rational free market evolve to incentivize the upstream communities to pace their release of flood waters? Has the huge increase in health care premiums lately underwritten enough infrastructure improvements to help? How can enterprises invest to ‘buy time’?
Mar 15 2020 at 3:52pm
Yes, I’m highly dubious about the “lessons” of history as they pertain to COVID-19 in 2020.
Take the 1918 Spanish Flu (please! ;-))…they didn’t even really know what they were dealing with. Now we have genetic sequencing. We have instantaneous worldwide communication that enables contact tracing. Back in 1918, people were hanging garlic around their necks to avoid illness. An N95 mask beats garlic cloves hung around the neck any day. 🙂
Mar 16 2020 at 11:17am
I don’t know. Enough garlic and you’ll have great social distancing effects.
Mar 16 2020 at 10:58am
I echo Henderson’s admission of ignorance about the epidemiology of this and Davies skepticism of extreme measures of geographical immobilization, and auto-isolation but really everything is a continuum and who can say what the exactly right point is.
Personally, I’m more concerned about how to minimize the economic damage of whatever amount of prevention/mitigation measures that get adopted.
Mar 16 2020 at 1:01pm
Does Stephen Davies know something about epidemiology that the Singaporean authorities (who have successfully contained COVID19 by contact tracing without a countrywide lockdown) or the Chinese authorities (who did the same in most of China outside Hubei province) don’t?
This is clearly something where governments can make mistakes, but the nature of the problem is such that there isn’t a market solution available – even conventional prediction markets don’t work (although the conditional prediction markets proposed by Robin Hanson would). Governments may have less skin in the game than market participants, but they have more than think tank “experts”.
Mar 16 2020 at 2:57pm
I think the reason for minimizing the spread today is that it is believed that we will gradually develop vaccines and antiviral treatments over the course of the next year that will make exposure far less dangerous in a year or so than right now. If whatever gains we might make in terms of ‘taming’ the virus in just one year of more frequent exposure are small or negligible, then minimizing exposure is still the best option for the short term. There were efforts to change people’s habits in India to ‘discriminate’ with respect to exposure to water-borne vs. airborne cholera (the latter is less severe) and I think it took years for cholera to become a lot milder (I have Paul Ewald’s research in mind I believe, it’s been a while since I read it).
And even with extensive social distancing and quarantining, more symptomatic people are still probably going to do less spreading; I doubt we could come close to self-isolating to the point of remotely suppressing the selective pressure toward mildness. So it seems unlikely that there’s a real risk, for the foreseeable future (the next few months at least), that we might over-quarantine ourselves. The prospect of an overwhelmed medical system and time-frame of both treatment/vaccine development and human-pathogen co-evolution suggest to me we should still be erring firmly on the side of reducing spread.
Mar 17 2020 at 7:43am
@steve d or Dave h
Your essay answered a question I did have—-i.e., what happens when lockdown ends? Your answer, absent a Vaccine, it just starts all over again. So we will see this very early in China and Korea as they gradually try to move back to normal. This, I have to assume, should cause panic squared relative to now—-. The reasonable belief may well be this is unstoppable until vaccines and heard immunity arrives.
I am on the wrong side of the age safety zone——and I am of normal health——maybe 68 is the new 64 but it’s not the new 54. Even at my non-ideal age, I wish this had never become public——meaning we should have let this thing go “free range”. But Italy was a freak show——and to at least be capable of treatment is minimal requirement which smoothing out the spread does——but at what cost? I do not think it is impossible we can see a 1930’s——except the great powers all have nukes.
I am just a random blogger reader, but why should sub-50 year olds be in lockdown? I live in North Central NJ. Schools are closed—why? They are no more at danger than they are of colds. Bars are closed, restaurants are closed. Gatherings of 10 or more are discouraged. National Guard is hovering around New Rochelle—-are we testing some scenario? All these sub 40’s can resist this——does not that weaken it?
Assuming you are right—-can we have different rules for different age groups. And about testing——what good does testing do? I think it is good if we use it for statistical inference, but few seem to be thinking that way. Just because I don’t have it today, says nothing about tomorrow. Maybe statistical inference can estimate symptom free diseases—-which may weaken the virus.
In blogoland, we can wing it. But in Government land——I see no one who gives me a sense that “they believe” they know even ideally what they want to do. Making an analogy to trading operations, the risk managers really are important, because they are able to give policy makers answers to a variety of “What ifs”. But you don’t ask RiskManagers to speak to the public. Fauci is the classic example—-his focus on hospital space. Good. ——I hope one or two questions came out of this mind dump
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