What Explains COVID-19’s Patterns of Transmission?

I wonder if anyone will pay attention to Faye Flam’s remarks at Bloomberg?

There are some weird things going on in the coronavirus data. It’s curious that cases dropped so fast, and have stayed pretty low, in the spring hot zones — New York, New Jersey and Connecticut. And why did cases remain so low in Idaho and Hawaii until recently?

The mainstream narrative is that it’s all about good behavior when cases go down — mask wearing and giving up our social lives for the greater good. And conversely, bad behavior must be what makes them go up. We talk about certain regions having the virus “under control,” as if falling cases are purely a matter of will-power. A sort of moral reasoning is filling in for evidence.

But why, then, have cases plummeted in Sweden, where mask wearing is a rarity?

This is the time to use scientific methods to understand what’s happening. The pandemic has gone on long enough to reveal patterns in the way it spreads. If it’s all about behavior, that’s a testable hypothesis. If, as a few speculate, dramatic drops in some places have something to do with growing immunity in the population, we can also turn that into a testable hypothesis.

I’m afraid it’s a complicated problem. Mask-wearing in County A might still reduce transmission in County B later on because people travel from County A to County B. I think that perfectly implemented and perfectly conformed with mask-wearing would probably reduce the rate of transmission of SARS-CoV-2 but I’m not so sure about mask-wearing when, where, and how it’s actually practiced.

Political polarization coupled with the instinct to suppress ideas that deviate from Established Orthodoxy impair our ability to arrive at or try strategies that deviate from that orthodoxy. I don’t see a simple way out of that fix.

11 comments… add one
  • Grey Shambler Link

    My apologies if you have seen this:

    “In Israel, investigators looking at 212 cases concluded that they could be linked back to 1 to 10 percent of people. And in an outbreak in a South Korea office tower, investigators found that about 45 percent of 216 workers got the virus from a single person. In the United States, an analysis from five counties in Georgia found that superspreading appeared to be “widespread across space and time,” and that 2 percent of the infected seeded 20 percent of the cases.”

    https://www.washingtonpost.com/health/2020/07/18/coronavirus-superspreading-events-drive-pandemic/

    Are they the most social animal in the group? They’re not coughing in everyone’s face, too obvious.

  • Piercello Link

    Dave, several times you have opined here, I think persuasively, that the US has transitioned/is transitioning to a post-literate society, and that this has various implications.

    Given the Coronavirus as an exemplar (but by no means the only one), might we also say that the combination of information velocity, urgency, and untrustworthiness is forcing society into a post-scientific age, or at least away from the cherished illusion of a scientifically informable polity?

    I don’t mean that the scientific method has suddenly up and quit working, but rather that no one trusts anyone else’s information, and there is too much of it anyway, and also that we all need actionable results right now, faster than slow, meticulous studies can acquire them.

    This would go well with the idea that tactically the environment is one of risk management (at speed and under uncertainty), rather than careful mapping of the upcoming course ahead of time.

    Thoughts?

  • Drew Link

    I think its like water finding its way. If we all lived like bubble boy then transmission would stop. The virus would presumably perish for lack of a host. That theory, and what seems to be foolishly guiding policy.

    In the real world there are avenues for transmission everywhere. Its basically unavoidable. One would expect vastly different results based upon relative distancing, hand washing, maybe or maybe not masks, geography, population density and probably 10 other factors. Its only when you open the system up and have significant outbreaks that you see the common rise to a peak 4-6 weeks later, then decline.

    It seems the strategy is clear – modest distancing probably only for the purpose of not overwhelming the health care system, and in (self) defense of the most vulnerable, or if you believe you can hybernate long enough for a vaccine or therapeutic drugs. But that should be a personal choice.

  • Are they the most social animal in the group? They’re not coughing in everyone’s face, too obvious.

    It is thought that so-called “super-spreaders” might be no different in behavior from anyone else. It might just be part of their inherent makeup.

  • Piercello:

    That’s an insightful comment with which I’m largely in agreement. I don’t have much to add to it other than that while these developments convey an advantage in some ways they place us at a serious disadvantage in others. We are a low trust society generally and the velocity and volume of information enables us to fragment into little trust groups across space which is potentially dangerous.

  • TarsTarkas Link

    ‘If, as a few speculate, dramatic drops in some places have something to do with growing immunity in the population, we can also turn that into a testable hypothesis.’

    I don’t think the dramatic drop in cases in China had anything whatsoever to do with herd immunity. When self-interest, politics and money are the prime motivators, the reporting will be gamed for the benefit of who controls the information. And this includes in this country and elsewhere. Which of course will blow any attempt to scientifically analyze the data out of the water and could lead to bad bad outcomes.

  • steve Link

    Two things. First, we have no idea at what point we achieve herd immunity. As an example we have some of the western Asias countries that decided to vigorously attack measles. Even with vaccination rates well into the 90% plus range, when someone from outside the country came with measles they still had a measles outbreak. So while it probably is well below 90%, and we could have meaningful effects at much lower rates, we really dont know. Its not much of a strategy.

    Next, the article again, I think, emphasizes heterogeneity in dealing with this disease. This is so much different than other respiratory viruses we have dealt with. Needs a lot more study to understand it. The long and thorough kind suggested above but which there isn’t much patience for.

    Last, concentrating only on masks as Flam does is stupid. Sweden has done a number of other things. No big groups over 50 allowed. The older kids are doing online school. Maybe one of those is more important than we think, especially in a country where a lot of people live alone (40%). So at this point we are guessing. This fall will give us a lot more answers.

    Steve

    Steve

  • Andy Link

    “So at this point we are guessing.”

    That’s been my basic complaint all along. We know more now than we did in March, but the lack of effort and coordination to get data that would better inform our decisions has been consistently lacking.

  • steve Link

    Andy- Did you read the WIRED article I linked? Our hospitals are set up to compete with each other. So when we need large, multi-institutional, expensive studies that doesnt go well. We actually have lots of fairly small retrospective studies, but that ends up being a problem as they arent strong enough to give meaningful results and people latch onto them anyway. These kinds of studies that dont have the support of the pharma or the device industry typically come from the big, well endowed universities or a federally funded group. We are starting to see them, but it will continue to take a while. (Often the best of these studies come from overseas since with more socialized medicine they have better built in monitoring and the medical community works together.)

    Steve

  • That’s a perfect example of what I mean when I say that our system has advantages and weaknesses. It’s also why I think that we’re likely to see a lot of medical advances coming from India. They’re not operating under a lot of the handicaps we are and they have plenty of physicians and engineers.

  • Andy Link

    “Did you read the WIRED article I linked?”

    Yes, I think the points and facts presented are in general agreement with what I said.

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