Rabies stands out as the most lethal virus for humans, resulting in nearly 100% mortality in infected individuals. Approximately 59,000 people succumb to rabies annually, with the highest fatality rates recorded in the least developed regions of Africa and Southeast Asia, where vaccination coverage is limited.

A list of rare viruses follows, characterized by exceptionally high mortality rates. Notable among these are Ebola (with a 50% mortality rate and approximately 15,000 fatalities throughout history), Avian influenza (also at 50% with 477 historical deaths, sparking significant concern in the past), and MERS (36% fatality rate, leading to 959 deaths).