Figure. Phylogenetic tree of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viruses isolated from passengers and airline crew members who traveled on the same flight from Boston, Massachusetts, USA, to Hong Kong, China. Human SARS-CoV-2 WIV04 is selected to be the root of this phylogenetic tree. The tree was constructed by using the neighbor-joining method. Only bootstrap values >80 are shown. Representative viruses from clades L, S, V, G, GH, GR, and O (others) are included in the analysis. Virus sequences from patients A–D reported in this study are grouped to clade G (GISAID [http://platform.gisaid.org] accession nos. EPI_ISL_476801 to EPI_ISL_476804). EPI ISL accession nos. for sequences retrieved in GISAID (http://platform.gisaid.org) are provided. Scale bar indicates estimated genetic distance.