So the testing of several hundred thousand cult members pushed both their CFR and test positive fraction lower than it otherwise would be, and rather obviously skewed their case age structure.
It skewed the age structure toward a younger demographic. Were you aware of this or did you assume that the religious group is skewed toward old people like typical churches? I didn’t realize this up until like ten days ago, but the Christian cult was predominantly pretty young people!
Nonetheless they have tested far less of their population than Iceland (about 5X less as of 3⁄20 according to ourworldindata), so if the ratio of infections/cases is 4x to 5x in Iceland it seems reasonable that it’s 10x to 20x in SK.
The reason I don’t consider it at all plausible that South Korea missed 80% or more of its cases is because of how quickly and lastingly they were able to gain control over their outbreak.
And about Iceland: Isn’t it really very clear that Iceland is weeks behind South Korea, and that Iceland’s numbers are therefore unrepresentatively low? For comparison, South Korea’s IFR was 0.6% at a point when they had 7,700 confirmed cases. I think this was roughly 20 days ago. So 20 days for South Korea’s IFR to go from 0.6% to 1.5% is how long it takes a majority of patients to die if the hospital conditions are favorable enough to give everyone good treatment. There weren’t many new confirmed cases in the meantime because the current count is 9,500. So with respect to the IFR Iceland is currently at (0.21%), if Iceland had their outbreak under control, we should expect that IFR to rise by a factor >2.5x. 2.5x is the lower bound because South Korea’s IFR was at 0.6% at a time when they already had dozens of deaths; by contrast, Iceland only has two deaths so they are way behind the timeline. (This comes from the effect that once true cases stop growing, the CFR rises up until all the illnesses take their course.) Expecting anything lower than a 4x increase from time delay is unreasonably low. So to make Iceland’s reported CFR comparable to South Korea’s, we should think of it as 0.84% rather than 0.21%. And then we can think about how many cases went undiagnosed in both countries (but maybe you did factor this in).
In addition, we have to factor in that Iceland doesn’t have their outbreak under control. Or do they? I didn’t check up on this, but I’d be surprised if they had the outbreak contained. My guess is they caught fewer cases than South Korea! Yes, Iceland did more testing per capita. But South Korea knew where to look! They really managed to get their outbreak under control. It’s very impressive and I feel like they’re not getting the credit they deserve.
Anyway, assuming Iceland still has community transmission, this would mean that through new testing, new confirmed cases will be added constantly to the total. Those cases will predominantly be recently confirmed cases where not enough time had passed for people to die. This will keep Iceland’s reported CFR at a low level for quite a while to come, but this provides basically zero evidence for the actual IFR being low.
UPDATE: I ended up looking up Iceland’s numbers, and it seems like they had almost 10% of their total cases confirmed only yesterday. So whether the growth regime is “linear” or not, I think this is definitely not comparable to South Korea’s numbers where the growth has been around 1% or 1.5% for several weeks.
It skewed the age structure toward a younger demographic. Were you aware of this or did you assume that the religious group is skewed toward old people like typical churches? I didn’t realize this up until like ten days ago, but the Christian cult was predominantly pretty young people!
Yes, I should have made this more clear—but it skewed it younger. Or at least that’s my explanation for their much higher than expected # cases in younger cohorts vs elsewhere. That should lower their CFR of course.
And about Iceland: Isn’t it really very clear that Iceland is weeks behind South Korea, and that Iceland’s numbers are therefore unrepresentatively low?
No this isn’t clear. Iceland’s case count entered a linear regime roughly 2 weeks ago—ie they do seem to have it under control (at least for now). Modeling one country as “X weeks behind” some other country is hazardous at best and also unnecessary as Iceland provides direct graphs on their daily #tests and #positive.
Edit: changed some numbers slightly after looking things up, to make them more accurate.
Modeling one country as “X weeks behind” some other country is hazardous at best and also unnecessary as Iceland provides direct graphs on their daily #tests and #positive.
I agree that it’s tricky to do the modelling correctly, but I feel like you’re not engaging with my point properly. I think the following argument I made is watertight:
There was a point when South Korea had several deaths (50ish) and thousands of cases (7,700) and their IFR was at 0.6%.
That’s roughly when they got their outbreak under control. The numbers slowed down tremendously, and 20 days later they are only at 9,500.
So in those 20 days, the reported CFR 2.5xed.
Iceland’s reported CFR never 2.5xed so far.
Therefore, they are way behind South Korea’s timeline even if we grant the point that Iceland has its outbreak contained (you may be completely right about this, because I didn’t follow it EDIT: I don’t think you’re right about it because Iceland’s numbers grew by almost 10% two days ago, which is still a somewhat large portion of new cases!).
The way I see it, this point is only wrong if somehow Iceland going from 1 deaths to 2 deaths is the equivalent stage of the timeline as South Korea’s deaths going from 50 to 144 (or whatever the numbers were). That seems highly improbable to me because it would mean that South Korea’s outbreak was 50 times larger than Iceland’s. That doesn’t seem right to me. (Though I guess if I had a strong belief that the hypothesis you’re defending is consistent with other data points, then this may not be a knockdown argument by itself? Would you expect South Korea’s outbreak to be 50x larger? No need to answer, of course. But if this argument updates you somehow, I’d be curious to hear!)
If you look at my estimate I’m already effectively predicting that their CFR will increase via predicting additional deaths. I think it makes more sense to predict future death outcomes in the current cohort of patients we are computing IFR rather than predicting future CFR changes based on how they changed in other countries and then back computing that into IFR.
The CFR can change over time not only because of delays in deaths vs stage of epidemic but also due to changes in testing strategy and or coverage, or even changes in coroner report standards or case counting standards (as happened at least once with china).
In terms of true number of infected, I’m predicting that SK has on the order of 100K to 200K cases and say 4K in Iceland, and I don’t find this up to ~50x difference very surprising. Firstly, it’s only about an 18 day difference in terms of first seed case at 25% daily growth.
SK’s first recorded case was much earlier in Jan 20 vs Feb 28 for Iceland. SK’s epidemic exploded quickly in a cult, Iceland’s arrived much later when they had the benefit of seeing the pandemic hit other countries—they are just quite different scenarios.
In terms of true number of infected, I’m predicting that SK has on the order of 100K to 200K cases and say 4K in Iceland, and I don’t find this up to ~50x difference very surprising. Firstly, it’s only about an 18 day difference in terms of first seed case at 25% daily growth.
I see. BTW our confidence intervals for the IFR have some overlap: 0.4% is my lower bound and your higher bound. :)
That’s interesting. Over the weekend I wrote a monte carlo simulation for the Iceland data incorporating a bunch of stuff including a lognormal fit to know median and mean time from confirmation to death. Going to write it up, but the TLDR: the posterior assigns most of it’s mass to the 0.2 to 0.4 range for reasonable settings. Want to do something similar for Diamond Princess and other places.
I expect the real IFR will vary of course based on age structure, cofactors (air pollution seems to be important, especially in Italy), and of course the rather larger differences in coroner reporting standards across jurisdictions and over time.
You can avoid alot of that by looking for excess mortality—which right now seems null in europe except for in Italy. But Spain has about the same cases and deaths per capita and no excess mortality.
It skewed the age structure toward a younger demographic. Were you aware of this or did you assume that the religious group is skewed toward old people like typical churches? I didn’t realize this up until like ten days ago, but the Christian cult was predominantly pretty young people!
The reason I don’t consider it at all plausible that South Korea missed 80% or more of its cases is because of how quickly and lastingly they were able to gain control over their outbreak.
And about Iceland: Isn’t it really very clear that Iceland is weeks behind South Korea, and that Iceland’s numbers are therefore unrepresentatively low? For comparison, South Korea’s IFR was 0.6% at a point when they had 7,700 confirmed cases. I think this was roughly 20 days ago. So 20 days for South Korea’s IFR to go from 0.6% to 1.5% is how long it takes a majority of patients to die if the hospital conditions are favorable enough to give everyone good treatment. There weren’t many new confirmed cases in the meantime because the current count is 9,500. So with respect to the IFR Iceland is currently at (0.21%), if Iceland had their outbreak under control, we should expect that IFR to rise by a factor >2.5x. 2.5x is the lower bound because South Korea’s IFR was at 0.6% at a time when they already had dozens of deaths; by contrast, Iceland only has two deaths so they are way behind the timeline. (This comes from the effect that once true cases stop growing, the CFR rises up until all the illnesses take their course.) Expecting anything lower than a 4x increase from time delay is unreasonably low. So to make Iceland’s reported CFR comparable to South Korea’s, we should think of it as 0.84% rather than 0.21%. And then we can think about how many cases went undiagnosed in both countries (but maybe you did factor this in).
In addition, we have to factor in that Iceland doesn’t have their outbreak under control. Or do they? I didn’t check up on this, but I’d be surprised if they had the outbreak contained. My guess is they caught fewer cases than South Korea! Yes, Iceland did more testing per capita. But South Korea knew where to look! They really managed to get their outbreak under control. It’s very impressive and I feel like they’re not getting the credit they deserve.
Anyway, assuming Iceland still has community transmission, this would mean that through new testing, new confirmed cases will be added constantly to the total. Those cases will predominantly be recently confirmed cases where not enough time had passed for people to die. This will keep Iceland’s reported CFR at a low level for quite a while to come, but this provides basically zero evidence for the actual IFR being low.
UPDATE: I ended up looking up Iceland’s numbers, and it seems like they had almost 10% of their total cases confirmed only yesterday. So whether the growth regime is “linear” or not, I think this is definitely not comparable to South Korea’s numbers where the growth has been around 1% or 1.5% for several weeks.
Yes, I should have made this more clear—but it skewed it younger. Or at least that’s my explanation for their much higher than expected # cases in younger cohorts vs elsewhere. That should lower their CFR of course.
No this isn’t clear. Iceland’s case count entered a linear regime roughly 2 weeks ago—ie they do seem to have it under control (at least for now). Modeling one country as “X weeks behind” some other country is hazardous at best and also unnecessary as Iceland provides direct graphs on their daily #tests and #positive.
Edit: changed some numbers slightly after looking things up, to make them more accurate.
I agree that it’s tricky to do the modelling correctly, but I feel like you’re not engaging with my point properly. I think the following argument I made is watertight:
There was a point when South Korea had several deaths (50ish) and thousands of cases (7,700) and their IFR was at 0.6%.
That’s roughly when they got their outbreak under control. The numbers slowed down tremendously, and 20 days later they are only at 9,500.
So in those 20 days, the reported CFR 2.5xed.
Iceland’s reported CFR never 2.5xed so far.
Therefore, they are way behind South Korea’s timeline even if we grant the point that Iceland has its outbreak contained (you may be completely right about this, because I didn’t follow it EDIT: I don’t think you’re right about it because Iceland’s numbers grew by almost 10% two days ago, which is still a somewhat large portion of new cases!).
The way I see it, this point is only wrong if somehow Iceland going from 1 deaths to 2 deaths is the equivalent stage of the timeline as South Korea’s deaths going from 50 to 144 (or whatever the numbers were). That seems highly improbable to me because it would mean that South Korea’s outbreak was 50 times larger than Iceland’s. That doesn’t seem right to me. (Though I guess if I had a strong belief that the hypothesis you’re defending is consistent with other data points, then this may not be a knockdown argument by itself? Would you expect South Korea’s outbreak to be 50x larger? No need to answer, of course. But if this argument updates you somehow, I’d be curious to hear!)
If you look at my estimate I’m already effectively predicting that their CFR will increase via predicting additional deaths. I think it makes more sense to predict future death outcomes in the current cohort of patients we are computing IFR rather than predicting future CFR changes based on how they changed in other countries and then back computing that into IFR.
The CFR can change over time not only because of delays in deaths vs stage of epidemic but also due to changes in testing strategy and or coverage, or even changes in coroner report standards or case counting standards (as happened at least once with china).
In terms of true number of infected, I’m predicting that SK has on the order of 100K to 200K cases and say 4K in Iceland, and I don’t find this up to ~50x difference very surprising. Firstly, it’s only about an 18 day difference in terms of first seed case at 25% daily growth.
SK’s first recorded case was much earlier in Jan 20 vs Feb 28 for Iceland. SK’s epidemic exploded quickly in a cult, Iceland’s arrived much later when they had the benefit of seeing the pandemic hit other countries—they are just quite different scenarios.
I see. BTW our confidence intervals for the IFR have some overlap: 0.4% is my lower bound and your higher bound. :)
Of note:
https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30243-7/fulltext
The latest professionals are suspecting a total infection-to-death rate of a normal population (not a cruise ship) of ~0.6%.
That’s interesting. Over the weekend I wrote a monte carlo simulation for the Iceland data incorporating a bunch of stuff including a lognormal fit to know median and mean time from confirmation to death. Going to write it up, but the TLDR: the posterior assigns most of it’s mass to the 0.2 to 0.4 range for reasonable settings. Want to do something similar for Diamond Princess and other places.
I expect the real IFR will vary of course based on age structure, cofactors (air pollution seems to be important, especially in Italy), and of course the rather larger differences in coroner reporting standards across jurisdictions and over time.
You can avoid alot of that by looking for excess mortality—which right now seems null in europe except for in Italy. But Spain has about the same cases and deaths per capita and no excess mortality.