A disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of individuals.

The study of the evolutionary relationships among biological entities (e.g., populations, species, genes).

SARS coronavirus 2, where SARS refers to severe acute respiratory syndrome.

Single nucleotide variation. A DNA sequence variation that occurs when a single nucleotide (adenine, thymine, cytosine, or guanine) in the genome sequence is altered.

The ability of a virus to productively infect a particular cell (cellular tropism), tissue (tissue tropism) or host species (host tropism).

The study of viruses.