(03-20-2020, 07:27 AM)burger Wrote: There are a lot of different CFR estimates coming out, almost daily now. Each uses different methods or data from a different country. As an interested person, I'd say the best thing is to just take a meta-analytic approach and average the CFRs instead of worrying about which used the best methodology*. I suspect that would put it in the 1-1.5% range.
*The only exception would be to totally ignore the new preprint, which I won't even link to, claiming a CFR of something like 0.05%. They also claim a staggering number of asymptomatic cases. That beggars the imagination.
I agree. Here are two papers analyzing China's numbers and making various assumptions, and coming to two numbers differing by a factor of 2 to 3 for China's CFR.
For the purposes here, and as used in one of the papers, I will use
Case Fatality Rate for fatality rate/diagnosed cases and
Infection Fatality Rate for fatality rate/infections (which includes some estimate of asymptomatic patients). In both papers, IFR was calculated from CFR based on the percentage of asymptomatic patients on the cruise ship.
Study 1 Study 2
The overall CFR they report are 1: 1.38% 2: 3.3%. IFR: 1: 0.657% 2: 1.6% Big difference.
They each go through a step of trying to deal with the fact that there were active cases in China when they took their numbers and adjusting the raw/crude/naive CFR (fatalities to date / diagnosed cases to date) to account for that. That number for the two studies were 1: 3.67% 2: 6%
As the number of unresolved cases in China decreases, that number can be better estimated to be between 4.0% and 4.4%.
As of March 19, the crude CFR in China is 4.0% (probably an underestimate). fatalities to date / (fatalities + recoveries) is 4.4% (probably an overestimate)
These two studies also gave their numbers for the 10-year age groups.
The overall CFR for a country is dependent on its demographics, as the CFR is much higher for older citizens. I multiplied their CFRs for age groups by the
population percentage in each age group and added those up. This gives a rough estimate for the overall CFR that can be expected. (Note this is mostly independent of how a country fights the pandemic, or how many get sick (modulo overwhelming the health system).)
| Country | Study 1 CFR | Study 2 CFR |
| China | 1.22% | 3.28% |
| India | 0.73% | 1.96% |
| Italy | 2.47% | 6.47% |
| Spain | 2.16% | 5.66% |
| UK | 1.96% | 5.11% |
| US | 1.22% | 3.32% |