Every distribution has fat tails. And if you need to do something about it, spend all your time on the tail events and don't bother with the small stuff.
That lesson, of course applies to stopping the spread of the corona virus. Stopping the negligible possibility that a hiker passes it to another hiker out on a (now closed) trail in the Santa Cruz mountains is beyond pointless. Stopping the tiny probability that a worker passes it to another worker in a thoughtfully structured high value business is equally pointless, and vastly more costly.
What do we know about the fat tail? Not as much as we should. Jonathan Kay's lovely Quillette essay on super spreader events covers a lot. (HT Marginal Revolution).
Jonathan points out that our scientists still don't reallhy know whether Covid-19 is spread primarily by large "ballistic" droplets, small persistent aerosol droplets, or contact with surfaces where droplets have landed. They don't know what kind of activities lead to spread. He investigated super spreader events to try to figure out. Jonathan put together all the information he could find on known Covid-19 super spreader events. He found 54, with details on 38. A bit more data collection and research effort on this crucial question would seem worthwhile.
I have a different goal -- what are the activities that we can reduce with greatest effect on the disease, and least economic cost, and within the everyday more apparent limitations of our political and government apparatus?
Like others (see Arnold Kling for example) I'm starting to despair of a way out. We will not have a vaccine for a long time, and kill the economy till the vaccine comes is not an option. Bend the curve, followed by vigorous test, trace and isolate would be possible, but I doubt the US, has the institutional capacity or political will for trace and isolate once we eventually get test to work. I cannot imagine our authorities imposing life in Wuhan (another MR HT). Paul Romer has articulately advocated a big push for widespread testing, notably by relaxing regulations (university labs not allowed to conduct tests, for example). Paul notes correctly that it's worth spending hundreds of billions of dollars on testing to save trillions of dollars of economic and fiscal damage. If we could test everyone every day, and get most of the positives to stay home, the virus would quickly peter out. But I'm dubious our government is capable of even this. Let it rip, argue many others, and wait for herd immunity. But I don't think our governments can do that either, as Boris Johnson found out.
Our governments can, however, come up with lists of banned activities. So let those lists have just a little more common sense. Let the lists of banned activities 1) focus on the tail of super spreader events 2) consider the economic damage vs. public health benefit.
The bottom line I get from Jonathan: It looks like the biggest transmission danger is large droplets exchanged by people talking loudly in large gatherings, in closed quarters, and where many different people interact. Yes, it may be transmitted in other ways, but this is the fat tail, and start with the fat tail. The even greater news: practically no GDP is lost if you ban the super spreading activities on his list.
However the rhetoric needs to change. Right now the calls are for "relax social distancing." This is exactly wrong. Keep social distancing, but relax economic prohibitions. The challenge is that our regulatory state finds it much easier to shut down business -- at tremendous economic cost -- than birthday parties.
Epidemiologists know about fat tails “20% of the individuals within any given population are thought to contribute at least 80% to the transmission potential” of previous infectious diseases.
Also from here (again HT Marginal Revolution)
We identified only a single outbreak in an outdoor environment, which involved two cases. Conclusions: All identified outbreaks of three or more cases occurred in an indoor environment, which confirms that sharing indoor space is a major SARS-CoV-2 infection risk.An added observation: Fat tails of superspreader events helps to explain why the virus seems to spread quickly in some places and not in others. 2,4, 8, 16, 32, 64, actually takes a while to get to 10,000. 2, 124, 256 from an early super spread event gets you there much faster.
Jonathan's events:
Many of the early SSEs, in fact, centered on weddings, birthday parties, and other events.The joy of life, but nearly zero GDP.
In fact, the truly remarkable trend that jumped off my spreadsheet has nothing to do with the sort of people involved in these SSEs, but rather the extraordinarily narrow range of underlying activities.Great news. We don't have to find dangerous people, just ban a small list of easily identifiable activities.
Of the 54 SSEs on my list for which the underlying activities were identified, no fewer than nine were linked to religious services or missionary work.Nearly zero GDP.
Nineteen of the SSEs—about one-third—involved parties or liquor-fueled mass attendance festivals of one kind or another, including (as with the examples cited above) celebrations of weddings, engagements and birthdays.
Five of the SSEs involved funerals.
Six of the SSEs involved face-to-face business networkingFinally some GDP, but easy to stop. We already have.
These parties, funerals, religious meet-ups and business networking sessions all seem to have involved the same type of behaviour: extended, close-range, face-to-face conversation—typically in crowded, socially animated spaces. This includes the many people infected by a bartender while being served at a raucous après ski venue in Austria, and party guests in Brazil greeting “each other with two kisses on the cheek [a local custom], hugs and handshakes.” The funerals in question are generally described as highly intimate and congested scenes of grieving among close friends and relatives. In the case of the SSE funeral in Albany, Georgia that devastated the local population, “people wiped tears away, and embraced, and blew their noses, and belted out hymns.
With few exceptions, almost all of the SSEs took place indoors, where people tend to pack closer together in social situations, and where ventilation is poorer. (It is notable, for instance, that the notorious outbreak at an Austrian ski resort is connected to a bartender and not, say, a lift operator.)
. At a February 15 festival in Gangelt, a town in Germany’s tiny Heinsberg district, “beer and wine flowed aplenty as approximately 350 adults in fancy dress locked arms on long wooden benches and swayed to the rhythm of music provided by a live band. During an interval in the programme, guests got up to mingle with friends and relatives at other tables, greeting each other as Rhineland tradition commands, with a bützchen, or peck on the cheek.” Since that time, more than 40 Germans from the Heinsberg district have died. It’s been called “Germany’s Wuhan.”
The virus makes no distinction according to creed, but does seem to prey on physically intimate congregations that feature some combination of mass participation, folk proselytizing and spontaneous, emotionally charged expressions of devotion. I
Three of the SSEs—in Japan, Skagit County, WA, and Singapore—involved concert-goers and singing groups belting out tunes together over a period of hours. ...
Another SSE involved a group of Canadian doctors engaged in a day of recreational curling. This is a sport that involves hyperventilating participants frenetically sweeping the ice with brooms while their faces are positioned inches apart, sometimes changing partners—an ideal climate for Flüggian infection. Indeed, this partner-swapping aspect of the activity seems to be a common feature of many suspected SSEs, such as square-dancing parties.
Four of the SSEs were outbreaks at meat-processing plants, in which “gut snatchers” and other densely packed workers must communicate with one another amidst the ear-piercing shriek of industrial machinery. ... high levels of noise do seem to be a common feature of SSEs, as such environments force conversationalists to speak at extremely close range.Some GDP here, but a work environment that one could easily fix.
When do COVID-19 SSEs happen? Based on the list I’ve assembled, the short answer is: Wherever and whenever people are up in each other’s faces, laughing, shouting, cheering, sobbing, singing, greeting, and praying.We can let a lot of GDP get going while respecting these rules.
What is not dangerous is just as informative to policy as what is dangerous
It’s worth scanning all the myriad forms of common human activity that aren’t represented among these listed SSEs: watching movies in a theater, being on a train or bus, attending theater, opera, or symphony...These are activities where people often find themselves surrounded by strangers in densely packed rooms—as with all those above-described SSEs—but, crucially, where attendees also are expected to sit still and talk in hushed tones.
The world’s untold thousands of white-collar cubicle farms don’t seem to be generating abundant COVID-19 SSEsThere is a lot of GDP there!
Moreover, I had trouble finding any SSEs that originated in university classrooms, which one would expect to be massive engines of infection if COVID-19 could be transmitted easily through airborne small-droplet diffusion.Universities -- which will face a huge question whether to reopen in the fall, might want to send their research doctors out to find the answer to this question now.
On the other hand, universities might be a microcosm of my above regulatory conundrum. A visitor from, China, say, visiting an average American college, might miss the fact that students are supposed to go to classes at all, and think it's one grand alcohol-fueled bacchanalia. Keeping "social" distance in the dorms and frats will be the university's problem, not the classroom. Good luck with that.
It’s similarly notable that airplanes don’t seem to be common sites for known SSEs, notwithstanding the sardine-like manner in which airlines transport us and the ample opportunity that the industry’s bureaucracy offers for contact tracing. Yes, New Zealand has one cluster that’s based around an infected but asymptomatic flight attendant. But the many known infections he caused took place at a wedding reception, not in an airplane. This flight attendant was running what was, in effect, an unintended experiment, with the passengers on board his aircraft playing the role of control group. And the results offer a microcosm of the nature of SSEs as a whole.Airlines might want to scream this from the rooftops. Given a huge bailout, the government might want to spend some time and money figuring out just how dangerous an airplane is.
The bottom line I read from Jonathan: Dear Fellow Citizens: Go out. Start up businesses. And shut up!
Update: thanks to commenters for typos.
Possible typo: Should 'The challenge is that our regulatory state finds it much harder to shut down business -- at tremendous economic cost -- than birthday parties.' be 'The challenge is that our regulatory state finds it much EASIER to shut down business -- at tremendous economic cost -- than birthday parties.' ?
ReplyDeleteSeems like the staple ban of of large gatherings (choose your own limit 10, 50 etc.) would be all you would really need from government. I suspect a natural desire for self-protection , e.g. mask wearing on an airplane or in a store, hand washing gets a significant way toward the remainder.
ReplyDeleteOf course there would be issues about how a "gathering" is defined, but it sounds like something where people are pretty stationary, e.g. a party, a church service or a football game rather visiting Disney World. Ideally this would be where people could make their own judgments about what is likely to be safe-- its not clear the the government is better positioned to make those judgments (very likely the opposite).
Unfortunately it is not clear to that, at least so, people are better at making judgement (as your last sentence applies). Google Lakewood NJ police arrest gatherings. There are way too many examples of gatherings of more than 10 people (and actually the emergency declaration made all weddings, funerals, etc. prohibited). So we have an area which is just over an hour from NYC, had rail to NYC had many people making bad personal choices to attend weddings, funerals and who knows what else.
DeleteWhen the NJ order went into affect the STATE had 1,300 cases. Today Lakewood, NJ has 1,000 (which is half of the entire county its located in).
A moderate number of people making clearly bad judgement has a major impact.
I suspect people generally get The Pareto 80/20 rule. 20% of drivers cause 80% of accidents. That means we drive defensively, buy insurance and observe traffic rules. Gyms are reopening in Georgia and people are observing the rules of safe distance as a matter of self interest. Other businesses will figure it out.
ReplyDeleteI am so disappointed by the tone of the protests insisting that the stay-at-home orders are unconstitutional or just plain fake news.
ReplyDeleteWhy didn't these protesters show up in face masks, standing 6 ft apart from each other, and just say "Look. We hear you. We can do what it takes to prevent further spread. Looks at us following the rules. Please let us open back up."
Instead they went about it in such a way that they are guaranteed to get an emotional reaction that does not end up with them achieving their goals.
It's possible that the emotional reaction IS the real goal. If it's not, it would imply that they are too stupid to figure out how to achieve their goals.
DeleteIrrespective of the negligible contribution to GDP (but what about welfare?), the religious/ritualistic nature of many of these activities is exactly why the government won't--perhaps even can't--ban these activities.
ReplyDeleteProductivity is worthless unless it leads to consumption. In fact, the only reason we care at all about productivity is because it enables consumption.
ReplyDeleteThus, consumption activities are more important than production activities. If we're going to shut down things, production should be the first thing we shut down, because nobody gets any utility from production on the first order. Consumption should be the absolute last thing to ban.
Speaking of super spreaders, don't forget the New Rochelle NY Bar Mitzvahs back in March....
ReplyDeletehttp://westchester.news12.com/story/41863994/2-rockland-caterers-test-positive-for-coronavirus-had-worked-bar-mitzvah-attended-by-new-rochelle-
John, I think you overestimate the government's ability to enforce its lists of banned activities when those activites DONT contribute to GDP. Enforcing a ban on business activites is easy, since most are in the formal sector. But how do you propose the government impose a ban on parties? Short of sending a DEA-like police force around the country, raiding homes and arresting partiers, I can't think of a way. And that possibility frightens me more than either an economic shutdown or an infectious disease.
ReplyDeleteMaybe, banning is the wrong way to think about it. At least, let people know what kinds of events are likely to lead to spreading: a party with lots of close contact vs. a quiet cubicle farm. Concern for one's own health and safety would lead many to avoid the loud party.
DeleteConsider AIDS and other STDs. A ban on unprotected sex is unenforceable. But, informing people about its risks can affect a lot of behavior.
Another stupidity of our current policy is that we focus on activities, not people. Someone with a cold is much more likely to be a superspreader than someone with no symptoms. But though we don't allow anybody to hike in the state parks, we allow people with colds, coughs, or even a diagnosed case of covid19 to go freely to pharmacies, grocery stores, and Wal-Mart and do all the sneezing they like.
ReplyDeleteIt should be noted that one way a person can be a superspreader is simply by being a slob, as a large minority of us are.
Please lets also not lose sight that all of this complex science and risk management is single-mindedly focused on infection avoidance – if not at all costs, at quite some cost. But for what? Remember your (John’s) long-standing plea that we focus on isolating those for whom being infected is more likely to cause serious health problems. We must start to coalesce around a view about what the virus’ real "infection consequence" rate is for relevant demographic groups. Notice that I say "infection consequence", because I want to give the virus' breadth of punch all of its due, not just its "fatality rate". Having said that, it is becoming increasingly clear that the infection fatality rate is tiny for those 65 and below -- even in possibly the worse socially-medically managed locality: NYC. How much public health policy should be about trying to interdict the flow of an ever shrinking minimal viral load? Why does this remind me of the War on Terror? (Where at least one could argue that a suitcase nuclear device that sneaks in...) Yet, I am glad that we may be able to coalesce around limiting spread minimization by managing SSE’s, but we should also take "Yes" for an answer on the virus’ effective lethality. Both of this should allow us to accomplish most of what we want in the medium term. And to be sure, this would still entail economic sacrifices. I expect the “suppressionists” (whether politically motivated or not) will seek to expand the universe of “at risk” (and thus “disabled”) to levels that will not allow our labor participation rate to get anywhere close to those in late-2019 any time soon.
ReplyDeleteKay's conclusions about use of large/mass transportation and SSEs doesn't square with Jeffery Harris's analysis of the role that NYC's subway system played in spreading covid-19:
ReplyDeletehttps://johnhcochrane.blogspot.com/2020/04/subways-and-virus.html
I think Kay's analysis is intriguing, but not statistically compelling -- and I assume he did not suggest it was. For example, let's remember how self-selected the analysis is. He analyzes SSE's and finds that many meet characteristics (X and Y). He does not look at all other candidate X and Y's which did not result in an SSE. However, one could say that his claim that some forms of social contact do not appear to result in SSE's is more solid.
DeleteI am planning my wedding and really wish it represented "nearly zero GDP" :)
ReplyDeleteLets look at it from a Schumacher ‘Small is Beautiful: A Study of Economics As If People Mattered’ perspective. The ‘thoughtfully structured high value business’ isn’t sustainable unless it has thoughtfully protected its employees from Covid-19. If businesses don’t provide minimal Covid-19 protectives to their employees like masks and gloves to avoid ‘ballistic’ droplets from the air and work surfaces, there won’t eventually be any able-bodied employees left and the potential pool of healthy labor will vanish too. Your supply of healthy workers becomes finite just like your revenue stream.
ReplyDeleteThe cleaner at your gym needs the same kit too, and if he/she drops cloths on the floor he/she can’t simply place them back on the next widely accessible and easily visible surface. Upon what (floor) surface were all those comfy gym shoes previously placed beforehand? How did the gym-bunny get to the gym? How did the cleaner get to the gym? Maybe the cleaner was reliant on the closed and confined space of a public transportation service like a bus because he/she couldn’t afford the services offered by the private sector whereas the gym bunny could. Precisely why he jumped into the closed and confined space of an Uber…..For he couldn’t afford the upkeep of a car. But just when and how are both modes of transport cleaned? Who else used the bus? Who else used the Uber? Did they all have gloves and masks? Sure many known infections have taken place indoors at close-contact weddings but at open-air public beach parties too, just not on airplanes, all because of the knowing thus far.
If Schumacher lived now, wearing a mask and gloves he’d push for a safely designed and useful Covid-19 contact tracing app from the government. One made readily available and freely accessible. An activities ban list or a total lockdown aren’t required; neither are right in the mid to long-term. We have to stop rising unemployment, bankruptcies, poverty and poor health. But with the right protective gear and a Covid-19 contact-tracing app we can better achieve this.