"Together with other Africa-derived BA.1-like sequence entries, the Omicron ancestors clustered in basal sister relationship between the Omicron clade sensu strictu, the BA.1 sublineage and Omicron ancestors belonging to the globally circulating B.1 lineage (Fig. 3, A and B). Phylogeographic analyses supported BA.1 origins in Western Africa preceding spread in Southern Africa (fig. S4), which was consistent with the PCR-based data (table S2)."

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