This suggests that South Korea missed about 90% of infections despite their extensive testing, which many have argued is responsible for their success at containment. This is so implausible that I’m hesitant to even look at the paper. But I bookmarked it and will report back if I find something interesting!
It’s interesting though that with the swine flu pandemic, experts were initially alarmed about a somewhat high IFR, and later on it turned out that the vast majority of cases were extremely mild. The WHO got accused of “crying wolf” over swine flu even though it ended up infecting more than 11% of the planet, and killing more than a hundred thousand people according to this Wikipedia article. So it was really bad, but initially some experts feared it would be a lot worse.
Might something similar be going on with Covid-19? I’m pretty sure that the answer is no, but I thought it was interesting that there’s a recent precedent for missing large numbers of milder cases.
I don’t think it’s the same with Covid-19 because:
Sneaky features of the disease, such as transmissibility prior to showing symptoms and the long incubation period, can already account for the R0 being high. The vast iceberg of completely asymptomatic cases is not needed to explain why this virus is so hard to contain.
Everything about South Korea’s data points toward a high IFR even in conditions where hospitals still have capacity.
Only 18% of people on the cruise ship were asymptomatic (this is strong evidence against the vast iceberg of asymptomatic cases), and the ship had an IFR of 1%. After adjusting for age, it doesn’t drop enough to go below 0.5%. In fact I’m not sure it drops substantially at all (I’ve seen different takes on this).
This study estimated an IFR of 1.6% for China’s numbers (up to a certain point in February). It has been praised as “looks solid” by some knowledgeable EAs and I’ve yet to see someone criticize it in a direct way.
This is more of a system-1 argument than something I can put numbers to, but from reading all the reports from hospitals in Italy and the Seattle area, I find it really hard to square IFR estimates lower than 0.5% with those reports. Doctors are constantly and desperately trying to communicate that it’s so much worse than everyone else seems to think. This virus really turns a lot of people lung tissue into something called “ground glass.” That sounds like it should be a lot more deadly than Swine flu.
Counterarguments to my view:
There was this tweet two days ago by an Italian doctor who reported that it seems as though 50%+ of the people tested in Veneto (and they went from household to household to test almost everyone, apparently) seemed to be asymptomatic.
I don’t think this counts for too much though, because it could also be that those people are still in the incubation period, or that the test has a somewhat high rate of false positives (I suspect that even 4% false positives would generate this sort of picture, but I’m not sure).
Maybe asymptomatic cases happen mostly in young people and children (there’s some evidence of this in South Korea, though it’s not so clear whether they mean “100% asymptomatic” or “mild symptoms”). There weren’t that many young people or children on the Diamond Cruise, so even though only 18% of people there were truly asymptomatic, this evidence might be consistent with the total rate of asymptomatic infections being at 50% for typical demographics.
That said, 50% of asymptomatic cases is nowhere near enough to get us down to a 0.1% IFR. The main update I could see happening is reducing other estimates by 25% or (maybe, if we stretch it) 50%, rather than by 70-90%.
IFR for the rest of 2020:
Unfortunately, I think we cannot directly rely on IFR estimates based on data from South Korea or the Cruise ship to estimate the IFR for the rest of 2020. I expect the majority of 2020 cases to happen in places where hospitals will be overstrained. I think this is likely to roughly double the IFR compared to more favorable conditions. (Note that this consideration wouldn’t necessarily double the estimated 1.6% by the study on China’s numbers, because those already factor in hospital crowding to a substantial degree. Most diagnosed cases happened in Hubei.)
Ground glass opacity is named after its visual appearance on a CT scan. Information I can find (and I’m not a doctor, don’t trust me at face value!) suggests that it’s generally reversible and doesn’t indicate any more severity than the pneumonia it’s detecting.
The obvious question to reconcile the Diamond Princess and Veneto is: do the tests have subclinical thresholds, and if so are they different? I don’t know where to begin researching that, though. (And as a more general concern, I worry the entire line of questioning might be overfitting, maybe there’s some random reason that has nothing to do with the general pandemic.)
You’re right re the “ground glass”, it’s describing what the lung looks like on imaging and is very non-specific. (Many etiologies and a long list of differential diagnoses).
As mentioned in a comment above, one of the (pretty highly credentialed) authors of this preprint has written two papers on the Diamond Princess, and so, excuse the appeal to authority, but any argument against this paper based on Diamond Princess doesn’t seem likely to invalidate conclusions of this preprint .
Also this squares seemingly squares more with John Ioannidis take on Corona:
“no countries have reliable data on the prevalence of the virus in a representative random sample of the general population.”
And that airborn-ish transmission is highly likely.
Projecting the Diamond Princess mortality rate onto the age structure of the U.S. population, the death rate among people infected with Covid-19 would be 0.125%.
I don’t find a source for this. The adjustments I saw looked different. If he’s right about those 0.125%, that would be an important update!
But it feels more plausible to me that the 0.125% thing went wrong somewhere because it just seems ruled out by South Korea, which unlike European countries has their outbreak contained. I can’t see how South Korea could somehow have missed 700% of their reported cases even though they are conducting 10,000 tests daily, and have fewer than 10,000 confirmed cases.
UPDATE: I took a shot at doing the age adjustment myself here. The summary: I don’t see how one can get anything below 0.3% and, adjusting for selection effects where the least healthy people probably avoid going on cruises, even going below 0.5% seems implausible to me. UPDATE2: I adjusted my estimates after finding more precise data. I still think 0.125% is too low, but I think something like 0.2% is perhaps already defensible. This suggests that the estimate was closer than I thought and I now consider the Diamond Princess not to be evidence in favor of IFR of 0.5% or higher (assuming no hospital overstrain).
As mentioned in a comment above, one of the (pretty highly credentialed) authors of this preprint has written two papers on the Diamond Princess, and so, excuse the appeal to authority, but any argument against this paper based on Diamond Princess doesn’t seem likely to invalidate conclusions of this preprint .
Interesting, I wasn’t aware of that! Makes me upshift that I was wrong, but also upshift that one author is responsible for several studies that I found dubious.
I looked through his list of publications and it seems he finished 2 papers on the prevalence of asymptomatic cases on the Diamond princess already (but not on fatality rates from there!). And the second one reports a point estimate that is outside the 95% confidence interval of the first paper, yet I don’t see any addendum to the first paper. This seems kind of odd?
And that airborn-ish transmission is highly likely.
I don’t have strong views on that. The only thing I feel confident about is that an IFR of below 0.5% seems extremely implausible.
This suggests that South Korea missed about 90% of infections despite their extensive testing, which many have argued is responsible for their success at containment. This is so implausible that I’m hesitant to even look at the paper. But I bookmarked it and will report back if I find something interesting!
It’s interesting though that with the swine flu pandemic, experts were initially alarmed about a somewhat high IFR, and later on it turned out that the vast majority of cases were extremely mild. The WHO got accused of “crying wolf” over swine flu even though it ended up infecting more than 11% of the planet, and killing more than a hundred thousand people according to this Wikipedia article. So it was really bad, but initially some experts feared it would be a lot worse.
Might something similar be going on with Covid-19? I’m pretty sure that the answer is no, but I thought it was interesting that there’s a recent precedent for missing large numbers of milder cases.
I don’t think it’s the same with Covid-19 because:
Sneaky features of the disease, such as transmissibility prior to showing symptoms and the long incubation period, can already account for the R0 being high. The vast iceberg of completely asymptomatic cases is not needed to explain why this virus is so hard to contain.
Everything about South Korea’s data points toward a high IFR even in conditions where hospitals still have capacity.
Only 18% of people on the cruise ship were asymptomatic (this is strong evidence against the vast iceberg of asymptomatic cases), and the ship had an IFR of 1%. After adjusting for age, it doesn’t drop enough to go below 0.5%. In fact I’m not sure it drops substantially at all (I’ve seen different takes on this).
This study estimated an IFR of 1.6% for China’s numbers (up to a certain point in February). It has been praised as “looks solid” by some knowledgeable EAs and I’ve yet to see someone criticize it in a direct way.
This is more of a system-1 argument than something I can put numbers to, but from reading all the reports from hospitals in Italy and the Seattle area, I find it really hard to square IFR estimates lower than 0.5% with those reports. Doctors are constantly and desperately trying to communicate that it’s so much worse than everyone else seems to think. This virus really turns a lot of people lung tissue into something called “ground glass.” That sounds like it should be a lot more deadly than Swine flu.
Counterarguments to my view:
There was this tweet two days ago by an Italian doctor who reported that it seems as though 50%+ of the people tested in Veneto (and they went from household to household to test almost everyone, apparently) seemed to be asymptomatic.
I don’t think this counts for too much though, because it could also be that those people are still in the incubation period, or that the test has a somewhat high rate of false positives (I suspect that even 4% false positives would generate this sort of picture, but I’m not sure).
Maybe asymptomatic cases happen mostly in young people and children (there’s some evidence of this in South Korea, though it’s not so clear whether they mean “100% asymptomatic” or “mild symptoms”). There weren’t that many young people or children on the Diamond Cruise, so even though only 18% of people there were truly asymptomatic, this evidence might be consistent with the total rate of asymptomatic infections being at 50% for typical demographics.
That said, 50% of asymptomatic cases is nowhere near enough to get us down to a 0.1% IFR. The main update I could see happening is reducing other estimates by 25% or (maybe, if we stretch it) 50%, rather than by 70-90%.
IFR for the rest of 2020:
Unfortunately, I think we cannot directly rely on IFR estimates based on data from South Korea or the Cruise ship to estimate the IFR for the rest of 2020. I expect the majority of 2020 cases to happen in places where hospitals will be overstrained. I think this is likely to roughly double the IFR compared to more favorable conditions. (Note that this consideration wouldn’t necessarily double the estimated 1.6% by the study on China’s numbers, because those already factor in hospital crowding to a substantial degree. Most diagnosed cases happened in Hubei.)
Ground glass opacity is named after its visual appearance on a CT scan. Information I can find (and I’m not a doctor, don’t trust me at face value!) suggests that it’s generally reversible and doesn’t indicate any more severity than the pneumonia it’s detecting.
The obvious question to reconcile the Diamond Princess and Veneto is: do the tests have subclinical thresholds, and if so are they different? I don’t know where to begin researching that, though. (And as a more general concern, I worry the entire line of questioning might be overfitting, maybe there’s some random reason that has nothing to do with the general pandemic.)
You’re right re the “ground glass”, it’s describing what the lung looks like on imaging and is very non-specific. (Many etiologies and a long list of differential diagnoses).
A good article re ground-glass opacification and what might have caused it.
As mentioned in a comment above, one of the (pretty highly credentialed) authors of this preprint has written two papers on the Diamond Princess, and so, excuse the appeal to authority, but any argument against this paper based on Diamond Princess doesn’t seem likely to invalidate conclusions of this preprint .
Also this squares seemingly squares more with John Ioannidis take on Corona:
“no countries have reliable data on the prevalence of the virus in a representative random sample of the general population.”
And that airborn-ish transmission is highly likely.
Ioannidis makes this claim:
I don’t find a source for this. The adjustments I saw looked different. If he’s right about those 0.125%, that would be an important update!
But it feels more plausible to me that the 0.125% thing went wrong somewhere because it just seems ruled out by South Korea, which unlike European countries has their outbreak contained. I can’t see how South Korea could somehow have missed 700% of their reported cases even though they are conducting 10,000 tests daily, and have fewer than 10,000 confirmed cases.
UPDATE: I took a shot at doing the age adjustment myself here. The summary: I don’t see how one can get anything below 0.3% and, adjusting for selection effects where the least healthy people probably avoid going on cruises, even going below 0.5% seems implausible to me. UPDATE2: I adjusted my estimates after finding more precise data. I still think 0.125% is too low, but I think something like 0.2% is perhaps already defensible. This suggests that the estimate was closer than I thought and I now consider the Diamond Princess not to be evidence in favor of IFR of 0.5% or higher (assuming no hospital overstrain).
Interesting, I wasn’t aware of that! Makes me upshift that I was wrong, but also upshift that one author is responsible for several studies that I found dubious.
I looked through his list of publications and it seems he finished 2 papers on the prevalence of asymptomatic cases on the Diamond princess already (but not on fatality rates from there!). And the second one reports a point estimate that is outside the 95% confidence interval of the first paper, yet I don’t see any addendum to the first paper. This seems kind of odd?
I don’t have strong views on that. The only thing I feel confident about is that an IFR of below 0.5% seems extremely implausible.