Omicron variant and other major or previous variants of concern of SARS-CoV-2 depicted in a tree scaled radially by genetic distance, derived from Nextstrain on 1 December 2021 (Wikipedia)

Now that the full sequence of Omicron has become known it’s remarkable to see how different Omicron is from all the other SARS-CoV-2 variants. It did not arise as a simple mutation of the others, it’s different in several ways. It has 60 RNA mutations causing 36 amino acid changes, several in the all-important spike protein. In a radial graph of genetic distance Omicron forms its own group way off to the side of the other variants (see diagram).