Main clusters are highlighted in different colours. The Wuhan reference genome is in larger font (GenBank accession number: NC_045512.2). The filled circles represent the main supported clusters (bootstrap support values are indicated at the level of the nodes). The scale bar at the bottom of the tree represents 0.000050 nt substitutions per site. The cluster containing the viral sequence of the Chinese tourist who had visited Rome, Italy (GISAID accession ID: EPI_ISL_412974) is in dark red. This cluster includes viral sequences derived from two samples (sputum and nasopharyngeal swabs) of another Chinese tourist visiting Rome (GISAID accession IDs: EPI_ISL_410545 and EPI_ISL_410546). The viral genome sequence (GISAID accession ID: EPI_ISL_412973) derived from a patient from Lombardy, Italy, is in a cluster highlighted in green, which is different from that containing the Chinese tourist’s sequence.