Short thread. I keep seeing claims on how some places may have reached herd immunity & calculations on whether a variant is more virulent or disporportionately affects the young etc. These are not easy things to discern so let’s not do confident back-of-the-envelope calculations.
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More younger people at the ICU compared to past? Could be an outbreak affecting them more because of network structure or behavior, vaccine/past immunity among elderly, ICU capacity change compared to past or even temp reporting blip in some countries, among many other things.
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A variant rising in an area could be founder or stochastic effects (one version happened to catch in a superspreading event—this pathogen is very overdispersed) or actually outcompeting others through more transmissibility. That’s why it took time to establish B.1.1.7 was.
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Similarly, previous (not that well-established) claims of high infection rate through models based on (maybe, maybe-not accurate) nonrandom seroprevalance are NOT, by themselves proof of widespread reinfection, or even that reinfected cases are severe or equally contagious etc.
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I used to teach methods and stats for sociology students, and epidemiology examples were always very useful because they really are among the thorniest to try to untangle. And I believe harmful to overclaim, and not necessary to do so to make basic public health recommendations.
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For example, the Brazil situation is horrific and deserves immediate attention, but this thread below is an example of how not to draw conclusions about P1 and it’s differential effect on young people. (The situation is bad enough without making unsupported claims like this).https://twitter.com/DrEricDing/status/1379995247812444162 …
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Similarly, it’s likely that P1 is more transmissible than the wildtype, but what’s happening in Brazil is completely compatible with an unchecked epidemic causing hospital system collapse even without higher transmissibility let alone any—unproven, speculative—effect on severity.
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Yes, of course. There are *SO MANY* confounders like that. We saw admission criteria change even in the United States during surges, affecting a lot of hospital-level statistics. Making claims about characteristics of variants/surges is hard, and it’s important to be careful.https://twitter.com/alexismadrigal/status/1380152737204072448 …
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Also. Do note that I’m not even coming close to claiming listing all possible issues/confounders in a thread, but just saying there’s a reason to be wary of back-of-the-envelope calculations that are either comforting (herd immunity!) or alarming (more severe among the young!).https://twitter.com/angie_rasmussen/status/1380149045365145600 …
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And more. These things really are hard, and there is no contradiction between epistemic humility when we do not yet understand all the characteristics of a surge/variant, and advocating to do all we can to limit the suffering regardless.https://twitter.com/zchagla/status/1380147897988177920 …
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As a simple cautionary example on not being too confident about reinfections driving Brazil’s P1 surge, compare with Uruguay (no past surge, hence cannot be reinfections). Uruguay also has P1 at least rising. Maybe earlier blood-bank sero study is unrepresentative? Hard to know.pic.twitter.com/NMIDvIVKtr
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Of course! I am honestly not drawing firm conclusions on what may or may not be happening. But the idea that one can look at ICU/death rates from *March 2020* and compare them to 2021 numbers and draw conclusions like Dr. Feigl-Ding does? Not a good idea and, imo, not helpful.https://twitter.com/pkalina/status/1380155394480340993 …
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Anyway, things are bad enough in many places around the world. There is definitely more transmissibility with at least some of the variants—and those will soon become dominant in places with outbreaks—and maybe some other effects mixed in (a lot less certainty on that).
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We all would like more clarity—me too!—but some things aren’t easy to figure out, and for good reason. Even “paper published” (peer-reviewed or not!) isn’t the end of the story. There really is a process, and I think it works well when we let it, but it takes time and engagement.
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Anyway, h/t to the tweet/meme from
@jbakcoleman last night that inspired this thread.
https://twitter.com/jbakcoleman/status/1380024099083186178 …This Tweet is unavailable.Show this thread -
Stellar comment in response to my last newsletter (about the unfathomable celebration of Florida's "Grim Reaper" attorney dude who was harassing people on beaches): "Nuance can feel like signal-weakening, so people over-signal to push the equilibrium." https://zeynep.substack.com/p/pandemic-as-metaphor/comments …pic.twitter.com/9hVO2woq4T
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Adding this as it's important even though it's sprinkled in the thread. Potential confounders make confident conclusions hard—but it's also hard to rule out direct causation. We can, and should, act against exponential threats even when facing uncertainty.https://twitter.com/rvenkayya/status/1380222793577594882 …
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Too often, a call for nuance and epistemic humility is conflated with inaction & decision paralysis, leading to the "signal overboost" noted above. Ideal world: perfectly possible to state limits of certainty while advocating for real action within the context of trade-offs.
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Seeing a lot of this in Long Covid discussions, too. We should be able to say that post-viral sequelae/Long Covid is real, important and too often neglected without ignoring baseline comparisons or turning it into something so ill-defined that it becomes easier to ignore/dismiss.
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Yeah sorry about that! I should just keep writing long-form about all this (I will!).https://twitter.com/Goldammerfeder/status/1380239103464247297 …
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End of conversation
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. What’s odds last spring 2020? 1 in 3.
That is likely an effect of
(HT