I know when I first started hearing about "superspreaders" I had the impression that there were certain individuals who somehow were capable of spreading the Wuhan virus more easily and widely than others. Of course that's not the case at all--the phenomenon of "superspreading" isn't about individuals. It's about social settings, very specific circumstances that are particularly conducive to spreading the infection.
The author of the article, Jonathan Kay, focuses on how major outbreaks--SSEs--of the Covid19 disease have occurred. And what he found by studying 54 examples around the world tends to strongly confirm the "6 feet/ten minute rule". The bottom line is that it's very unlikely that you'll catch the virus from casual contact. Infection requires fairly close and prolonged contact. These excerpts--taken out of context-- ill give you an idea of what he's talking about:
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.
... all seem to have involved the same type of behaviour: extended, close-range, face-to-face conversation—typically in crowded, socially animated spaces.
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.)
Some of the examples may surprise you a bit, but reflection will show that they do fall into that pattern. Truly crowded public conveyances may fall into that category as well, but in the US that's very much the exception in daily life throughout most of the country. Does that explain what I mean by "human geography" in the US being different? As offering more protection? This isn't to say that this virus isn't highly dangerous, but might it be more manageable for much of this country than expert opinion suggests?
Helpfully, Kay goes on to contrast those examples of activities that seem conducive to superspreading with other common activities that, at first glance, you might take to be conducive to infection but which, in practice, appear not to be.
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 latter activities may seem like rarified examples, but they are important once you take stock of all those wealthy infectees who got sick in March, and consider that New York City is a major COVID-19 hot spot). 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 SSEs—despite the uneven quality of ventilation one finds in global workplaces. This category includes call centers (many of which are still operating), places where millions of people around the world literally talk for a living. (Addendum: there are at least two examples of call-centre-based clusters, both of which were indicated to me by readers after the original version of this article appeared—one in South Korea, which overlaps with the massive Shincheonji Church of Jesus cluster; and the other in Jamaica.)
These are pretty specific observations that seem to me to be very relevant to any discussion on reopening. If this interests you, you may want to compare the information Kay has come up with with the views expressed by Michael Osterholm in an inteview with Mika and Joe:
The interview is almost 15 minutes long and through most of it Osterholm is talking about the certainty that there's more bad news ahead, that this is a war and not a battle, that we're in it for the long term, that the virus will be back in the fall. Osterholm is a highly regarded public health and epidemiology specialist with a vast amount of practical experience. I've cited him numerous times in the past. Nevertheless, you may want to try to square what he says with Kay. In the final segment, starting around 11:30, Osterholm is pressed on "opening up." He has some good things to say, but he speaks only in generalities whereas Kay offers some pretty specific ideas.
Ya know, if it assumed to get worse in the cooler, colds months like the flu, wouldn't the reverse assumption be true? I mean, it's not the first time Trump states something widely panned, but turns out he was spot on.ReplyDelete
Since latest reports are that it's very sensitive to sunlight, that might mean sensitive to heat as well. And maybe sunny climates.Delete
OTOH, if you ever wondered why we don't want this thing on the loose:
One month ago when the country went into lockdown to prepare for the first wave of coronavirus cases, many doctors felt confident they knew what they were dealing with. Based on early reports, covid-19 appeared to be a standard variety respiratory virus, albeit a contagious and lethal one with no vaccine and no treatment. They’ve since seen how covid-19 attacks not only the lungs, but also the kidneys, heart, intestines, liver and brain.
Increasingly, doctors also are reporting bizarre, unsettling cases that don’t seem to follow any of the textbooks they’ve trained on. They describe patients with startlingly low oxygen levels — so low that they would normally be unconscious or near death — talking and swiping on their phones. Asymptomatic pregnant women suddenly in cardiac arrest. Patients who by all conventional measures seem to have mild disease deteriorating within minutes and dying"
Of course, it remains the case that most deaths are among seniors, but it's also true that this is not the kind of thing you want to just ignore and hope it goes away--not if you have some alternative.
The material quoted by Mark is from an article in the WaPo:Delete
A mysterious blood-clotting complication is killing coronavirus patients Once thought a relatively straightforward respiratory virus, covid-19 is proving to be much more frightening
Strokes due to clots in 20- and 30-year olds. Clots in large blood vessels, the most damaging kind (Nick Cordero, a Broadway actor, lost his leg last week due to that). The finding, upon autopsy, of myriad little clots in the lungs of deceased COVID-19 victims.
No, not just a bad cold or flu as some doubters and scoffers would have us believe.
New York City did an antibody test to check on the spread of virus. It turned out that 21% of people tested were positive, meaning they had it, recovered and were asymtomatic. To mea that means it has been here a lot longer than we think. It also shows the quarantine was futile. How can you stop people from going outside if they don't know if they are sick? We might as well reopen the country.Delete
Testing positive doesn't necessarily mean you "had it". By definition, if you are asymptomatic then you don't "have it"--if IT is Covid19 the disease. It means you've been exposed to the SARS-CoV-2 virus.Delete
There have been no studies that support your contention that the virus was spreading in NY "a lot longer than we think." All studies indicate late January - early February:
That means that the quarantine was NOT futile, although elements of it may well have been misguided. But in fairness, little was known back then and there's still much to learn.
The people we should be really angry with are those who authorized gain-of-function research--Fauci. And who funded Wuhan lab for that kind of research instead of pressuring the Chinese to stop it. Fauci again.
My point re the quarantine is that slowing the spread of this kind of novel disease is always a good thing, all else being equal. The quarantine in NYC started 3/20, and that still was time to have a positive effect. You start the quarantine and as people start reporting sick you begin to get a handle on it. You stop the easy spread, which is important with this virus because it doesn't spread as easily as flu. In that sense you probably get a lot more bang for your quarantine buck with this virus than with a flu virus that transmits more easily.Delete
Mark - I read something about where Covid 19 may be affecting red blood cell, which causes a lack of oxygen. And the worst thing to do is put a person on a ventilator.ReplyDelete
Found the reference:
NYC ER Doc questioning whether ventilators are being used in the wrong manner causing lung damage.
And more on this:
With the key point:
*Specifically Hussman Foundation report states "On the weight of published research regarding SARS, MERS, ARDS, and the emerging literature on SARS-CoV-2 my impression is that one of the reasons SARS-CoV-2 has such a high fatality rate is that it is being treated in the context of pulmonology when it should also be treated in the context of rheumatology."
From comments, when they used to be allowed, at:
So what's your take on that comment?Delete
Pulmonology is lungs. Rheumatology is about the immune system being over excited, and that sounds like what Covid 19 is doing.Delete
The challenge is a Dr. in the US has little liability for doing the accepted treatment, such as using ventilators, even if ineffective.
When patients are not showing sufficient oxygen in their blood, they are put on oxygen. When they are unable to breath satisfactorily on their own, they are put on ventilators. What alternative is there?Delete
Use Nitric Oxide in conjunction with ventilator.Delete
When discussing superspreaders, it's worth considering Nassim Taleb's observations on the subject; he argues the spread of a viral infection (like many things in nature and finance) has a fat-tailed distribution that follows a power law. These types of distributions are where we get the Pareto "80/20" Rule, in which 80% of the outcome is produce by only 20% of the population, or 50% of the outcome is caused by just 4%.ReplyDelete
The implication is that a few superspreaders are likely responsible for a very large component of an epidemic virus' Ro (which is simply the average reinfection rate over the whole population.)
For this reason, Taleb has opined that quarantining the superspeaders alone (assuming one could identify them and round them up early) might be sufficient to drive the CV-19 reinfection rate below 1.0, which would snuff out the epidemic spread. Not everyone agrees with Taleb on that point, but whether or not superspreader quarantine alone is enough to stop CV-19, his point is well taken -- if we focus the bulk of our effort to contact trace and ID and quarantine the superspreaders first and foremost, it will produce the biggest reduction in the reinfection rate compared to almost anything else we can do, even if it isn't quite enough to snuff out the spread of CV-19.
The analogy that I think everyone is familiar with is the change in policing in NYC back in the 1990s, when the police commissioner realized that when they analyzed the crime data, they discovered 80% of the crime was being committed by 20% of the criminal population. This 20% is analogous to the superspreaders in an epidemic. So, the police in NYC began to focus on where the crime was and focused on catching, prosecuting, and keeping in jail for as long as possible the members of the criminal population who were the "supercriminals." This included affirmative efforts to block early parole of such criminals once convicted.
As we all know, crime rates collapsed in NYC after these and other changes were made to LE policy in NYC. (I'm not convinced all of the decrease in crime is due to these policy changes, but some of it clearly is.)
The other interesting point in the original superspreader study is the narrow range of activities that resulted in the superspreader effect. This raises the possibility that in addition to IDing superspreaders and quarantining them, another potential mechanism to short circuit a dangerous epidemic in the early phase would be to impose restrictions during serious epidemics on the types of activities where superspreading occurs, e.g., wedding receptions and similar events that involve close, prolonged face-to-face (for airborne spread infections) social contact by large groups of people.
It also illustrates that for such airborne transmitted infections, face masks are likely to help significantly. Taleb argues that the benefit of face masks is multiplicative, since it reduces the ability of the infection to be spread by an infected person wearing a mask, plus the masks worn by the non-infected further reduce THEIR exposure, if any exists.
So the practical answer may be a combination of early hot-spot contact tracing with emphasis on finding and quarantining superspreaders most of all, restricting close, extended contact social events (like wedding receptions,) and general mask wearing in settings with large number of people in proximity (shopping, work, etc.) This combined approach could be sufficient to snuff out a CV-19 epidemic, with minimal economic disruption.
Some notable “gatherings” that turned out to be superspreaders:ReplyDelete
In Skagit County, Washington, 45 members of a 60-person choir rehearsal became ill with COVID-19.
None had shown symptoms prior to attending rehearsal and there were no known cases in their county, despite people contracting the novel coronavirus in nearby Seattle.
In Austin, Texas, 28 out of 70 students who booked a plane to Mexico for a spring break trip have tested positive for the virus.
Meanwhile, a town in Georgia where more than 200 mourners gathered to attend a funeral has become a viral hotspot, with dozens of relatives and attendees falling ill.
More here: https://www.healthline.com/health-news/hone-social-gathering-can-quickly-spread-covid-19