Virus stock image. 3d illustration of a group of microscopic virus on a black background. A virus is made up of a core of genetic material (DNA or RNA), and surrounded by a protective coat called a capsid which is made up of protein. These microscopic parasites that lack the capacity to thrive and reproduce outside of a host body. Viruses are the most common biological entities on Earth. Viruses are the cause of contagion and widespread events of disease and death. In recent times there was the 2009 swine flu pandemic and in 2014 the outbreak of Ebola in West Africa. The 2019 Coronavirus pandemic has caused the most disruption accross the world.