Category: Medicine
Social distancing should never be too restrictive
That is the topic of a new paper by Farboodi, Jarosch, and Shimer, published version in here. They favor ” Immediate social distancing that ends only slowly but is not overly restrictive.” Furthermore, they test the model against data from Safegraph and also from Sweden and find that their recommendations do not depend very much on parameter values.
Here is an excerpt from the paper:
…social distancing is never too restrictive. At any point in time, the effective reproduction number for a disease is the expected number of people that an infected person infects. In contrast to the basic reproduction number, it accounts for the current level of social activity and the fraction of people who are susceptible. Importantly, optimal policy keeps the effective reproduction number above the fraction of people who are susceptible,although for a long time only mildly so. That is, social activity is such that, if almost everyone were susceptible to the disease, the disease would grow over time. That means that optimal social activity lets infections grow until the susceptible population is sufficiently small that the number of infected people starts to shrink. As the stock of infected individuals falls,the optimal ratio of the effective reproduction number to the fraction of susceptible people grows until it eventually converges to the basic reproduction number.
To understand why social distancing is never too restrictive, first observe that social activity optimally returns to its pre-pandemic level in the long run, even if a cure is never found. To understand why, suppose to the contrary that social distancing is permanently imposed, suppressing social activity below the first-best (disease-free world) level. That means that a small increase in social activity has a first-order impact on welfare. Of course, there is a cost to increasing social activity: it will lead to an increase in infections. However,since the number of infected people must converge to zero in the long run, by waiting long enough to increase social activity, the number of additional infections can be made arbitrarily small while the benefit from a marginal increase in social activity remains positive.
Recommended, one recurring theme is that people distance a lot of their own accord. That means voluntary self-policing brings many of the benefits of a lockdown. Another lesson is that we should be liberalizing at the margin.
If I have a worry, however, it has to do with the Lucas critique. People make take preliminary warnings very seriously, when they see those warnings are part of a path toward greater strictness. When the same verbal or written message is part of a path toward greater liberalization however…perhaps the momentum and perceived end point really matters?
For the pointer I thank John Alcorn.
Fast Grants update
Fast Grants has now made over 100 grants and contributed over $18 million in funding biomedical research against Covid-19, all in a little over two weeks’ time since project conception. If you scroll down the home page, you can see a partial list of winners (we are more concerned with getting the money out the door than keeping the list fully updated, but it will continue to grow).
Fast Grants is part of Emergent Ventures, a project of the Mercatus Center, George Mason University. And I wish to thank again all of those who have contributed to this project, either financially or otherwise. A partial list of financial contributors can be found at the above link as well.
People are dying from coronavirus because research is too slow
For years, there’s been talk about making the clinical trial process more standardized, and cheaper, so that the same rules would apply each time a study needed to be run. There’s even been discussion that what are known as pragmatic trials — large, simple, randomized studies in which less data are collected — might be conducted using electronic health records. But that hasn’t happened at the pace it should.
The reason involves another part of the problem. Clinical trials are principally run by drug and medical device companies in order to obtain regulatory approvals, with public health authorities only picking up the slack in rare examples. But the result is that we have not built a system that would make studies simpler; most patients have little opportunity to participate in research; and we are too slow to figure out what works.
What would the system look like if we fixed it? It would make it easier to study drugs for heart disease, where studies are so large and expensive that many companies don’t test their medicines. It would ease studies for rare cancers, which are currently problematic because the right patients are hard to find. And it could create a medical information superhighway that would power health care through the next century.
That is from Matthew Herper in StatNews. Via Malinga Fernando.
It is better to do lots of tests, even if they are not entirely accurate
We find that the number of daily tests carried out is much more important than their sensitivity, for the success of a case-isolation based strategy.
Our results are based on a Susceptible-Exposed-Infectious-Recovered (SEIR) model, which is age-, testing-, quarantine- and hospitalisation-aware. This model has a number of parameters which we estimate from best-available UK data. We run the model with variations of these parameters – each of which represents a possible present state of circumstances in the UK – in order to test the robustness of our conclusion.
We implemented and investigated a number of potential exit strategies, focusing primarily on the effects of virus-testing based case isolation.
The implementation of our model is flexible and extensively commented, allowing us and others to investigate new policy ideas in a timely manner; we next aim to investigate the optimal use of the highly imperfect antibody tests that the United Kingdom already possesses in large numbers.
There is much more at the link, including the model, results, and source code. That is from a team led by Gergo Bohner and also Gaurav Venkataraman, Gaurav being a previous Emergent Ventures winner.
The essential Ben Thompson on isolation and quarantine
…while I have written about Taiwan’s use of cellphone-enforced quarantines for recent travelers and close contacts of those infected, I should also note that every single positive infection — symptomatic or not — is isolated away from their home and family. That is also the case in South Korea, and while it was the case for Singaporean citizens, it was not the case for migrant workers, which is a major reason why the virus has exploded in recent weeks.
Here’s the thing, though: isolating people is hard. It would be very controversial. It would require overbearing police powers that people in the West are intrinsically allergic to. Politicians that instituted such a policy would be very unpopular. It is so much easier to let tech companies build a potential magic bullet, and then demand they let government use it; most people wouldn’t know or wouldn’t care, which appears to matter more than whether or not the approach would actually work (or, to put it another way, it appears that the French government sees privacy as a club with which to beat tech companies, not a non-negotiable principle their citizens demand).
So that is why I have changed my mind: Western governments are not willing to take actions that we know work because it would be unpopular and controversial (indeed, the fact that central quarantine is so clearly a violation of liberties is arguably a benefit, because there is no way people would tolerate it once the crisis is over). And, on the flipside, that makes digital surveillance too dangerous to build. Politicians would rather leverage tech companies to violate liberty on the sly, and tech companies, once they have the capability, are all too willing to offload the responsibility of using it wisely to whatever government entity is willing to give them cover. There just isn’t much evidence that either side is willing to make hard choices.
That is from Ben’s Stratechery email newsletter, gated but you can pay to get it. There is currently the risk that “test and trace” becomes for the Left what “chloroquine” has been for Trump and parts of the political right — namely a way to make otherwise unpalatable plans sound as if they have hope for more than “develop herd immunity and bankrupt the economy in the process.”
To be clear, I fully favor “test and trace,” and I’ve worked hard to help fund some of it. That said, I wonder if we will anytime soon reach the point where it is a game changer. So when people argue we should not reopen the economy until “test and trace” is in place, I increasingly see that as a kind of emotive declaration that others do not care enough about human lives (possibly true!), rather than an actual piece of advice.
Covid-19 liability reform for the eventual reopening
That is the topic of my latest Bloomberg column, here is one excerpt:
If an infected but asymptomatic worker shows up at work and sickens coworkers, for example, should the employer be liable? The answer is far from obvious. Liability exists not to shift unmanageable risk, but rather to induce management to take possible and prudent measures of precaution.
Another problem with liability law in this context is that the potential damages are high relative to the capitalization of most businesses. Covid-19 cases often pop up in chains; there have been many cases from a single conference, or in a single church choir, or on a single cruise ship. If a business or school is host to such a chain, it could be wiped out financially by lawsuits. In these cases the liability penalties do not have their intended deterrent effect because the money to lose simply isn’t there…
Another problem with liability in this setting has to do with jury expertise. Are random members of the public really the best people to determine acceptable levels of Covid-19 risk and appropriate employer precautions? Juries are better suited for more conventional applications of liability law, such as when the handyman fixing your roof falls off your rickety ladder. Given the unprecedented nature of the current situation, many Covid-19 risk questions require experts.
Finally, there is the issue of testing. Businesses could be of immeasurable help by testing their employees for Covid-19, as additional testing can help limit the spread of the virus (if only by indicating which workers should stay home or get treatment). Yet the available tests are highly imperfect, especially with false negatives. If businesses are liable for incorrect test results, and their possible practical implications, then business will likely not perform any tests at all, to the detriment of virtually everybody.
I recommend modest liability for some sectors, and zero liability, bundled with a New Zealand-like accident compensation system, for other sectors. And of course some very dangerous sectors should not be allowed to reopen at all, though I am more sympathetic to regional experimentation than are some people on Twitter.
Nursing home estimates of the day
From the (since updated) report: “In the remaining 5 countries for which we have official data (Belgium, Canada, France, Ireland and Norway), and where the number of total deaths ranges from 136 to 17,167, the % of COVID-related deaths in care homes ranges from 49% to 64%).”
“Residents of long-term care facilities account for half of the total deaths in Massachusetts”
Those are all from an email from Michael A. Alcorn.
The Bali heterogeneity?
From a Kevin Kelly email to me:
Another weird data point on the highly heterogeneous nature of this virus.
A friend of mine who lives in Bali says there have been 2 confirmed Covid-19 deaths on their island of 4.3 million residents. Yet according to him:
That makes it around 25.000 tourists from mainland China every week.
And until mid-January 2020, before the outbreak of the Corona pandemic, there were 5 direct flights from Wuhan per week.
During January 2020, 113,000 tourists from China visited Bali. During December 2019 when the Coronavirus was already spreading the number of arrivals from China was even higher because December is very busy in Bali.
So during the months of December 2019 and January 2020, approximately 220,000 tourists arrived from China alone.
Here are the official Covid-19 numbers as of 17th April 2020.
Confirmed cases: 113 | Recovered: 32 | Deaths: 2
The Crematorium in Bali’s capital city Denpasar does not see any increase in the number of cremations.
The hospitals do not have a flood of patients. There is hardly any talk on Social Media by people reporting about folks falling ill with Corona like symptoms.
The only thing I could find in Social Media groups is that business owners in Bali have reported an unusually high number of employees falling ill during November and December 2019.
Here is his Medium post
https://medium.com/@dominik.vanyi/bali-covid19-an-involuntary-experiment-in-epidemiology-immunology-a62485ce5924
Why the low status of opposition to child abuse?
Michael Kaan emails me:
Hi Tyler, I’m a healthcare professional in Canada and a long-time reader of your blog. For the past couple of years, observing the culture wars and various elections, I’ve noticed that child abuse is an extremely rare topic among the cultural left: the highly visible progressive segment that drives wokeness, is culturally powerful, etc. You know what their dominant concerns are. (On the right it’s basically non-existent.)
While there’s nothing obviously wrong with their attention to sexual and racial discrimination, the energy put into it is disproportionate to the massive social cost of child abuse. Rates vary around the world, but in general it looks like about 30% of all children globally suffer some sort of serious maltreatment each year, often many times a year, repeated over multiple years.So one can easily estimate that billions of people have experienced this. In other words, more people have been abused as children than have experienced war, famine, or epidemics.
The impact and costs of this have been measured (low academic achievement, health problems, low earnings, drug and alcohol use, etc.), and child abuse is sometimes lethal. What puzzles me is why it has no legs politically. Among the woke crowd, if child abuse is mentioned it’s usually in terms of discrimination against girls or sexual minorities. But there are really no prominent voices actively campaigning to mitigate child abuse generally.Why is this? Is it overly complex? Is the phenomenon too widely dispersed demographically, so that an evil agent group isn’t easily identified? Does its persistence foreground chronic failures of the welfare state (if that’s the case)? Is it boring?
For a start, I would note that virtually everyone is again child abuse, so opposing it doesn’t make anyone significant look worse. But I am sure there is much more to it than that.
Spit Works
A new paper finds that COVID-19 can be detected in saliva more accurately than with nasal swab. As I mentioned earlier a saliva test will lessen the need for personnel with PPE to collect samples.
Rapid and accurate SARS-CoV-2 diagnostic testing is essential for controlling the ongoing COVID-19 pandemic. The current gold standard for COVID-19 diagnosis is real-time RT-PCR detection of SARS-CoV-2 from nasopharyngeal swabs. Low sensitivity, exposure risks to healthcare workers, and global shortages of swabs and personal protective equipment, however, necessitate the validation of new diagnostic approaches. Saliva is a promising candidate for SARS-CoV-2 diagnostics because (1) collection is minimally invasive and can reliably be self-administered and (2) saliva has exhibited comparable sensitivity to nasopharyngeal swabs in detection of other respiratory pathogens, including endemic human coronaviruses, in previous studies. To validate the use of saliva for SARS-CoV-2 detection, we tested nasopharyngeal and saliva samples from confirmed COVID-19 patients and self-collected samples from healthcare workers on COVID-19 wards. When we compared SARS-CoV-2 detection from patient-matched nasopharyngeal and saliva samples, we found that saliva yielded greater detection sensitivity and consistency throughout the course of infection. Furthermore, we report less variability in self-sample collection of saliva. Taken together, our findings demonstrate that saliva is a viable and more sensitive alternative to nasopharyngeal swabs and could enable at-home self-administered sample collection for accurate large-scale SARS-CoV-2 testing.
The FDA has also just approved an at-home test collected by nasal swab, a saliva test should not be far behind.
Hat tip: Cat in the Hat.
Trading off consumption vs. covid-19 deaths
Somehow I missed this April 6 paper by Hall, Jones, and Klenow:
This short note develops a framework for thinking about the following question: What is the maximum amount of consumption that a utilitarian welfare function would be willing to trade off to avoid the deaths associated with COVID-19? Our baseline answer is 26%, or around 1/4 of one year’s consumption.
So what does that imply for optimal policy? Will we manage to lose both? Via Ivan Werning.
Claims about networking and social distancing
Our models demonstrate that while social distancing measures clearly do flatten the curve, strategic reduction of contact can strongly increase their efficiency, introducing the possibility of allowing some social contact while keeping risks low. Limiting interaction to a few repeated contacts emerges as the most effective strategy. Maintaining similarity across contacts and the strengthening of communities via triadic strategies are also highly effective. This approach provides empirical evidence which adds nuanced policy advice for effective social distancing that can mitigate adverse consequences of social isolation.
That is from a new paper by Per Block, et.al. I do not consider this a confirmed result, but it is consistent with how my intuitions have been developing, and the success in containing Covid-19 on various smallish islands.
My Conversation with Philip Tetlock
Here is the audio and transcript, here is part of the summary:
He joined Tyler to discuss whether the world as a whole is becoming harder to predict, whether Goldman Sachs traders can beat forecasters, what inferences we can draw from analyzing the speech of politicians, the importance of interdisciplinary teams, the qualities he looks for in leaders, the reasons he’s skeptical machine learning will outcompete his research team, the year he thinks the ascent of the West became inevitable, how research on counterfactuals can be applied to modern debates, why people with second cultures tend to make better forecasters, how to become more fox-like, and more.
Here is one excerpt:
COWEN: If you could take just a bit of time away from your research and play in your own tournaments, are you as good as your own best superforecasters?
TETLOCK: I don’t think so. I don’t think I have the patience or the temperament for doing it. I did give it a try in the second year of the first set of forecasting tournaments back in 2012, and I monitored the aggregates. We had an aggregation algorithm that was performing very well at the time, and it was outperforming 99.8 percent of the forecasters from whom the composite was derived.
If I simply had predicted what the composite said at each point in time in that tournament, I would have been a super superforecaster. I would have been better than 99.8 percent of the superforecasters. So, even though I knew that it was unlikely that I could outperform the composite, I did research some questions where I thought the composite was excessively aggressive, and I tried to second guess it.
The net result of my efforts — instead of finishing in the top 0.02 percent or whatever, I think I finished in the middle of the superforecaster pack. That doesn’t mean I’m a superforecaster. It just means that when I tried to make a forecast better than the composite, I degraded the accuracy significantly.
COWEN: But what do you think is the kind of patience you’re lacking? Because if I look at your career, you’ve been working on these databases on this topic for what? Over 30 years. That’s incredible patience, right? More patience than most of your superforecasters have shown. Is there some dis-aggregated notion of patience where they have it and you don’t?
TETLOCK: [laughs] Yeah, they have a skill set. In the most recent tournaments, we’ve been working on with them, this becomes even more evident — their willingness to delve into the details of really pretty obscure problems for very minimal compensation is quite extraordinary. They are intrinsically cognitively motivated in a way that is quite remarkable. How am I different from that?
I guess I have a little bit of attention deficit disorder, and my attention tends to roam. I’ve not just worked on forecasting tournaments. I’ve been fairly persistent in pursuing this topic since the mid 1980s. Even before Gorbachev became general party secretary, I was doing a little bit of this. But I’ve been doing a lot of other things as well on the side. My attention tends to roam. I’m interested in taboo tradeoffs. I’m interested in accountability. There’re various things I’ve studied that don’t quite fall in this rubric.
COWEN: Doesn’t that make you more of a fox though? You know something about many different areas. I could ask you about antebellum American discourse before the Civil War, and you would know who had the smart arguments and who didn’t. Right?
And another:
TETLOCK:
…I had a very interesting correspondence with William Safire in the 1980s about forecasting tournaments. We could talk a little about it later. The upshot of this is that young people who are upwardly mobile see forecasting tournaments as an opportunity to rise. Old people like me and aging baby-boomer types who occupy relatively high status inside organizations see forecasting tournaments as a way to lose.
If I’m a senior analyst inside an intelligence agency, and say I’m on the National Intelligence Council, and I’m an expert on China and the go-to guy for the president on China, and some upstart R&D operation called IARPA says, “Hey, we’re going to run these forecasting tournaments in which we assess how well the analytic community can put probabilities on what Xi Jinping is going to do next.”
And I’ll be on a level playing field, competing against 25-year-olds, and I’m a 65-year-old, how am I likely to react to this proposal, to this new method of doing business? It doesn’t take a lot of empathy or bureaucratic imagination to suppose I’m going to try to nix this thing.
COWEN: Which nation’s government in the world do you think listens to you the most? You may not know, right?
Definitely recommended.
The Subways Seeded the Massive Coronavirus Epidemic in New York City
New York City’s multitentacled subway system was a major disseminator – if not the principal transmission vehicle – of coronavirus infection during the initial takeoff of the massive epidemic that became evident throughout the city during March 2020. The near shutoff of subway ridership in Manhattan – down by over 90 percent at the end of March – correlates strongly with the substantial increase in the doubling time of new cases in this borough. Maps of subway station turnstile entries, superimposed upon zip code-level maps of reported coronavirus incidence, are strongly consistent with subway-facilitated disease propagation. Local train lines appear to have a higher propensity to transmit infection than express lines. Reciprocal seeding of infection appears to be the best explanation for the emergence of a single hotspot in Midtown West in Manhattan. Bus hubs may have served as secondary transmission routes out to the periphery of the city.
That is from a new NBER working paper by Jeffrey E. Harris.
The Japanese coronavirus story
You may recall that some time ago MR posted an anonymous account of how the coronavirus problem actually was much worse in Japan than was being admitted by the Japanese government and broader establishment. It is now clear that this Cassandra was correct.
I can now reveal to you the full story of that posting behind the first link, including my role in it. Here is the opening excerpt:
By March 22nd, I strongly suspected there was a widespread coronavirus epidemic in Japan. This was not widely believed at the time. I, working with others, conducted an independent research project. By March 25th we had sufficient certainty to act. We projected that the default course of the epidemic would lead to a public health crisis.
We attempted to disseminate the results to appropriate parties, out of a sense of civic duty. We initially did this privately attached to our identities and publicly but anonymously to maximize the likelihood of being effective and minimize risks to the response effort and to the team. We were successful in accelerating the work of others.
The situation is, as of this writing, still very serious. In retrospect, our pre-registered results were largely correct. I am coming forward with them because the methods we used, and the fact that they arrived at a result correct enough to act upon prior to formal confirmation, may accelerate future work and future responses here and elsewhere.
I am an American. I speak Japanese and live in Tokyo. I have spent my entire adult life in Japan. I have no medical nor epidemiology background. My professional background is as a software engineer and entrepreneur. I presently work in technology. This project was on my own initiative and in my personal capacity.
I am honored to have played a modest role in this story, though full credit goes elsewhere, do read the whole thing. Hashing plays a key role in the longer narrative.