The infection fatality rate is closely related to the case fertility rate as it applies to infectious outbreaks. But, it also calculates death proportions among all the affected people which includes all the undiagnosed and asymptomatic subjects. The main job of IFR is that it looks out for infections among healthy men. IFR looks for the Fatality rate of not only the sick but also those who are healthily infected. Those who have the disease detected as well as those who have the disease undetected or non-tested. There may be individuals who are affected but are not showing any symptoms. These people are known as inappropriate or subclinical. But, they can easily infect others. It is said that theoretically, IFR can never exceed the value of CFR.