These figures vary by region and over time, and are influenced by the volume of tests, the quality of the health system, the treatment options, the time elapsed since the start of the epidemic, as well as demographic characteristics such as age, gender, and especially health. The case-death ratio represents the number of deaths divided by the number of cases diagnosed over a given period.
Nambari hizi hutofautiana na eneo na wakati unapozidi, huathiriwa na kiwango cha kupima, ubora wa mfumo wa utunzaji wa afya, aina ya matibabu, wakati wa kutokea kwa kwanza, na hali ya idadi ya watu kama umri, jinsia, na hali ya afya kwa ujumla.Kiwango cha kifo hadi kisa huonyesha nambari ya vifo ikigawanywa na nambari ya visa vilivyotambuliwa katika muda fulani.