Epidemics and pandemics are long-term phenomena which date back to the distant past and are caused by both human and natural factors. People have always faced various epidemics and pandemics that not only killed a huge percentage of the population, but also destroyed entire economies and countries. Some researchers claim that throughout history, nothing has killed as many people as viruses, bacteria and parasites, causing more death than all wars or natural disasters like earthquakes or volcanoes, combined. Over the centuries, epidemics and pandemics have changed not only the course of history, but also to a large extent the whole of humanity in almost every way.