Fig. 1

SARS-CoV-2 genomic surveillance. a Phylogenetic tree of 19,438 SARS-CoV-2 genomes. Up to December 31, 2020, more than 295,000 complete genomes were submitted to the GISAID database. Each circle in this tree represents a genome that was sequenced over time, since the beginning of the pandemic. As SARS-CoV-2 establishes new infections, its descendants form lineages of genetically related viruses, which can circulate more locally, as shown in lineages represented by threads of circles with similar colors (as shown in red, at the top of panel a), or may have more heterogeneous distributions, as depicted in lineages with multiple colors, highlighting the exchange of viruses between geographic regions (as shown at the bottom of panel a). b State level distribution of SARS-CoV-2 genomes shown in panel a (see acknowledgement Table S1). All regions of the world were impacted by the pandemic, some more than others. As a result, an imbalance in the distribution of genomes worldwide (depicted in panel b as bubbles of distinct sizes) is evident. The differences in genome sampling across continents and countries may not only be the result of epidemic control via distinct public health strategies (as observed in New Zealand and Australia, for example) but may also result from socioeconomic disparities at national and international scales, where some regions (e.g., South and Central America, most regions in Africa), despite being hard hit by the pandemic, are unable to conduct genomic surveillance at a scale comparable to that of rich countries in North America and Europe. Analyses and illustrations were respectively generated using augur and auspice (by nextstrain.org) [11]