Like all viruses, the coronavirus mutates. Above: In this depiction of the the South African coronavirus variant B.1.531, the thin yellow band around the rim of indicates a mutation site. The virus spike (red) is attaching to a human cell receptor (blue).

In the main mutation site (yellow) of the South African coronavirus variant B.1.531, a glutamic acid amino acid is replace by a lysine one at the position 484. A spike protein (red) is bound to an angiotensin converting enzyme 2 (blue), which is embedded in a human cell membrane.