Qualified reads were mapped to NC_045512, a SARS-CoV-2 genome reference using Burrows-Wheeler Aligner (v0.7.12-r1039), and a bam file was produced.11 In this bam file, the variation was confirmed by comparing with genome using SAMtools (v1.3.1).12 For genome-base phylogeny analysis, 37 strains including BetaCoV/Korea/KCDC03/2020 were used in combination with BetaCoV/Korea/SNU01/2020.