These are two ways of measuring the fatality rate (or risk or ratio) of a particular disease. The case fatality rate refers to the percentage of people who died from a specific disease compared to how many total people were officially diagnosed with the disease in a particular period of time. The infection fatality rate is very similar, but the denominator includes asymptomatic and undiagnosed—but estimated—infections rather than just confirmed cases. The IFR will always be lower than the CFR because the denominator is bigger, but the numerator is the same number. The IFR attempts to account for all sick and healthy infected persons and must sometimes rely on estimates if testing and other surveillance methods are not comprehensive.
