Fig. 1: Pango lineage dynamics.

a Global variant dynamics between Jan. 1, 2022 and Jan. 18, 2023. Omicron variants have been through waves of global dominance since Omicron began to spread in late 2021. BA.1 and BA.1.1 very rapidly replaced Delta globally. BA.2 then replaced BA.1 as the globally dominant form. Within the BA.2 lineage, BA.2.12.1 began to expand in North America, but BA.2, including the BA.2.12.1 sublineage, was soon replaced by BA.5 in a nearly global selective sweep. Currently, BA.5 is being replaced by a very complex array of distinct lineages that have evolved from either BA.2, BA.5, BA.2.75, or expanding recombinant lineages. (Pango lineage designations indicate recombinant lineages by starting their designation with an X.) Distinct common contemporary BA.2.75 sublineages (with associated forms of Spike defined in Supplementary Fig. 1) are considered individually. All BA.2.75-related sublineages are labeled in shades of green and arranged at the top of the graphs. b Examples of countries illustrating the increase in prevalence of BA.2.75-related lineages. India and Singapore are shown because they were among the first countries to transition to a highly prevalence of BA.2.75 in the summer of 2022; in both cases, the XBB recombinant lineage soon transitioned to the most prevalent form, by October of 2022, but currently BA.2.75 sublineages with additional mutations are once again beginning to expand in these countries. Vietnam and South Korea are displayed because they have a high prevalence of the BA.2.75 sublineage BN.1. Australia and New Zealand each have an array of BA.2.75 lineages that in combination dominate recent sampling. The UK and Sweden are both examples of countries were BA.2.75 sublineages are increasingly sampled. Supplementary Figs. 2 and 3 show that the two most common sublineages of BA.2.75, CH.1 and BN.1, are increasingly sampled in most countries once they are established, and illustrate the analysis used to identify the countries of interest for display here. All data are from GISAID; the illustrations were created by using the “Embers” web-based tool at cov.lanl.gov²⁶.