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Time-resolved maximum clade credibility phylogeny of the Omicron BA.1 and BA.2 sub-lineages (n = 161, sampled between November 2021 and January 2022). Mutations that characterize Omicron sub-lineages are indicated on the respective branches. The posterior distribution of the tMRCA for each sub-lineage is also shown. The countries as a trait for each sample are denoted by distinct colours.
