Fig. 1: Circulating strains of SARS-CoV-2 are fast-changing.
From: Challenges and developments in universal vaccine design against SARS-CoV-2 variants
a Genetic relationships of global SARS-CoV-2 strains. The unrooted phylogenic tree is constructed by Nextstrain according to the sequences of 3050 SARS-CoV-2 spike glycoproteins from GISAID collected between December 2019 and October 2022 (https://nextstrain.org/ncov/gisaid/global/6m?l=unrooted&m=div). The tree is colored by clade and branch length represents the divergence of each clade. The Omicron variants show the highest antigenic distinction to the ancestral strain. b Time course of prevalent SARS-CoV-2 variants substitutions worldwide. The x-axis represents the date and the y-axis shows the frequencies of viral strains in percentage. Omicron subvariants have rapidly outcompeted previously prevalent Delta variants and become dominant.
