Figure 1: Phylogenetic analysis of SARS-CoV-2 from early COVID-19 cases and virus sequences obtained from the Huanan market.
(A) Phylogenetic tree of SARS-CoV-2 viral genomes collected before Jan 20, 2020. Tip colors correspond to different samples (red: market environmental samples and directly linked cases; yellow: Wuhan cases, with those indirectly linked to the Huanan market labeled; blue: all global cases). Symptom onset dates for cases are shown when known. The branch leading to A20 is slightly longer than other sequences with two substitutions from the root due to its slightly greater proportion (2.2%) of undetermined nucleotides. (B) tMRCA estimates for SARS-CoV-2 viral sequences from samples collected by February 14th 2020, obtained from globally collected viral samples (blue), samples obtained from Wuhan (yellow), and samples from the Huanan market or cases with direct market contact (red). The 95% highest posterior density (HPD) interval of each distribution is highlighted and the dashed line denotes the sampling date of the earliest genome (December 24th 2019).