Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea.
SARS-CoV-2, a member of the subfamily CoronavirinaeĪ virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism.
For a more accessible and less technical introduction to this topic, see Introduction to viruses.
