I’ve seen these reports but I don’t understand the math. The true simple CFR meeting actual deaths as reported over actual cases as reported should be adjusted for the course of disease which would make it in places like Italy well over 10% and in other places perhaps 4-6. % or more and we know China’s data, the only place with a major outbreak where it’s really run its course, is bullshit. How do you get to 0.1%? Maybe I’m missing something here but you’d have to believe there were probably 50-100 times the Number of reported cases that were actual cases which would mean the US would have to have had 50-100 million people already have contracted the disease but 98-99 pct of them had no idea. I’m not seeing that as a passes the smell test possibility. But again maybe I missing something here.
I think there are also several issues that are causing the reported CFR to be understated, that counteract to some degree the “denominator problem” from undiagnosed mild cases. The one that I think is the most important is the simple understanding of cohort analysis which I just don’t ever see explained or included any calculations. The number of cases is rising exponentially, and there’s a six week course roughly to the disease, so the number of deaths at any point in time is six weeks behind the number of diagnosed cases at any point in time and the number of cases is increasing exponentially, so this seems like a big error. I have to say I’m truly surprised by how we are this far into this thing and it doesn’t seem like anybody has even done some of the basic mathematical maneuvering you would need to do to understand this or at least they haven’t done that and explained it very publicly.
I hear a lot about how we may be seriously underestimating the CFR denominator, due to undiagnosed mild cases. Ok I get that.
What I don’t hear much about is that the numerator is also probably understated at any point in time for several reasons.
First I don’t trust the China data I think it’s understated and that’s the oldest, most mature data we have.
Second, in an exponentially growing disease with something like a 6 week course from infection through to mortality/recovery, we will always have diagnosed cases that are 6 weeks, or whatever the true course is, ahead of the final death tally and as the diagnosed cases are rising so rapidly, including those weeks and weeks worth of diagnosed but unresolved cases could add up to a huge amount of error to a simple deaths/cases CFR analysis that would significantly understate what the final CFR will look like. Cohort analysis does not appear to have caught on in the CFR calculation world from what I’ve been reading.
Third, I’ve read that there are likely a significant number deaths that are probably attributable to COVID-19 that are not being counted as Covid-19. The death rate in northern Italy over the last month, even when all the COVID-19 attributed deaths are removed, is significantly higher than it has been in similar periods in the past I have read. I believe the same is true in New York City. So if these stories are correct, there are likely more COVID-19 deaths than are being counted.
So while it is probably true that the denominator is understated, it seems to me that it’s also very likely true that the numerator is also understated making it very difficult for me to believe any of these estimates are very accurate until both these issues are addressed.
Has anyone seen anything that explains some of these issues and calculates a cohort-based death rate, which somehow estimates or adjusts were incorrect, time shifted or under counted Fatality data?
