Figure 2.

Dendrogram displaying the SNP differences between SARS-CoV-2 viral sequences that were related (<2 SNP differences) or possibly related (3–5 SNP differences) in the 5 transmission clusters and in 3 employee controls with COVID-19 infection. Clades were determined based on the Nextstrain classification system. The Wuhan-Hu-1 reference genome is shown for comparison. Dates indicate the date of specimen collection. Abbreviations: COVID-19, coronavirus disease 2019; Emp, employee; Pat, patient; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SNP, single nucleotide polymorphism.