A large number of commentators, including mainstream media, report this as a 2% CFR, calculated as 639/31586 = 2%. While this is worse than the seasonal flu, it is much less than SARS (10%) and MERS (30%), so no need to worry, they say.
Of the 31586 confirmed cases, about 85% have been diagnosed in the last 10 days. Many are in worsening condition and we do not know if they will die or recover. Therefore, to estimate the CFR, we can do one of two things: - We can consider only the cases for which an outcome is known: dead or recovered. This would lead us to estimate the CFR as 639/(639+1777) = 26%. - We can assume that after a certain time period, e.g. 1 week, the patient has either died or recovered. A week ago, there were 9803 confirmed cases. This would lead us to estimate the CFR as 639/9803 = 6%. Obviously, we do not know the right lag, but something between 1 and 2 weeks seems plausible given what we know about the disease. And it is certainly not zero.
