The case fatality rate is the number of deaths related to a given disease out of the total number of cases of the same disease. It is expressed as a percentage.
It allows to express the seriousness of a disease and the effectiveness of a treatment. To calculate this rate, it is important to know the number of deaths due to the disease, but also the total number of people who contracted the disease.
Not to be confused
The case fatality rate should not be confused with the death rate ( http://success.openhealth.fr/fr/articles/3947946-taux-de-mortalite ) which expresses the total number of deaths, whatever the cause , in a population and a period defined on the average total population over the same period.
1,000 people have a disease, 15 people die from the disease. Then the case fatality rate will be: