CFR vs IFR

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   The latest Situation Report from WHO [Report # 30] contains two terms that initially seem to mean the same thing.

As with many discussions that end at cross purposes one should look carefully at the definitions of words.

 WHO wrote:

case fatality ratio (CFR, the proportion of cases who die), 
infection fatality ratio (IFR, the portion of all of those infected who die),

In my understanding if you are infected with SARS-Cov2 then you have a case of Corvid-19, so the two terms should mean the same thing.

Later on in the report there is further clarification,  in that for WHO whenever you read CFR you should automatically translated it to CCFR (Confirmed CFR).  The following also implies to me  (but it is not clearly stated) that a "case" might only be counted if symptoms show.

 The confirmed case fatality ratio, or CFR, is the total number of deaths divided by the total number of confirmed cases at one point in time. Within China, the confirmed CFR, as reported by the Chinese Center for Disease Control and Prevention,9 is 2.3%. This is based on 1023 deaths amongst 44 415 laboratory-confirmed cases as of 11 February. This CFR does not include the number of more mild infections that may be missed from current surveillance, which has largely focused on patients with pneumonia requiring hospitalization; nor does it account for the fact that recently confirmed cases may yet develop severe disease, and some may die. As the outbreak continues, the confirmed CFR may change. Outside of China, CFR estimates among confirmed cases reported is lower than reported from within China. However, it is too early to draw conclusions as to whether there are real differences in the CFR inside and outside of China, as final outcome data (that is, who will recover and who will die) for the majority of cases reported from outside China are not yet known.
Modeling is a helpful tool to try to account for missed cases, such as those that are mild cases potentially missed in current surveillance activities, and the time lag between onset and death. Using an estimated number of total infections, the Infection Fatality Ratio can be calculated. This represents the fraction of all infections (both diagnosed and undiagnosed) that result in death. Based on these available analyses, current IFR estimates10,11,12 range from 0.3% to 1%. Without population-based serologic studies, it is not yet possible to know what proportion of the population has been infected with COVID-19.

Lesson: While I consider WHO to be accurate in the figures that they give, they are based on a very narrow definition, and so give an inaccurate over all position.  It is a clever political move that plays into the hands of those governments who what to suppress some of the data.  

Note: from the differences between the CCFR and the IFR quoted above, WHO is saying that the estimated actual rate of infection is between 3 and 10 times larger than the information published by China.   