Right now there is no meaningful Case Fatality Rate (to use the “official terminology”) as there are not enough resolved cases to provide sufficient data.
For example, the Case Fatality Rate in India is 0% as all 3 cases there resolved without any deaths. In the Philippines, however, of the 3 cases, one recovered, one died and one is unresolved, so the Case Fatality Rate is 33% but could jump to 67% without a change in the number of affected. That’s why it isn’t useful to try and calculate that with too little time for cases to resolve in large numbers.
However, we *can* calculate a sort of instantaneous CFR for the Philippines as 50% (1 dead, 1 recovered), South Korea as 31.25% (10 dead, 22 recovered), Iran as 100% (16 deaths, 0 recoveries), Italy 87.5% (7 deaths, 1 recovery). Those numbers look pretty bad, but that is the nature of small data sets. All of those numbers should drop, eventually approaching something like 2% except where the medical infrastructure breaks down (like in Wuhan) where the numbers will be significantly higher. And also, Iran, where we can expect a 600% CFR due to the propensity of the powers that be to multiply things by random numbers for political effect.
As for the Mortality Rate (”official terminology”) right now it is at pretty close to zero. Of 8+ billion people in the world, only some 2700 or so have died from the corona virus (official WHO numbers).
I use the simple method of estimating the CFR based on the reports of numbers of infected vs. numbers of deaths.
I know very well that a real CFR is only determined after the cases have resolved. So it is always a historical number.
At this point, there are many unknowns with this virus. For all I know, it could become less lethal and fade to an ordinary cold virus as it adapts to human hosts. The number of cases strongly suggests that it can maintain sustained human to human transmission, but other than that, it is hard to make any determinations about the behavior of this virus. And doing these analyses is no longer my line of work, so I’m not digging up a lot of information for the time being.