Household transmission of SARS-CoV-2 R.1 lineage with spike E484K mutation in Japan

ABSTRACT

We aimed to investigate SARS-CoV-2 emerging lineage harboring variants in receptor binding domain (RBD) of spike protein in Japan. Total nucleic acids were subjected to whole genome sequencing on samples from 133 patients with coronavirus disease (COVID-19). We obtained the SARS-CoV-2 genome sequence from these patients and examined variants in RBD. As a result, three patients were infected with SARS-CoV-2 harboring E484K mutation in January 2021. These three patients were relatives; one was in the 40s, and two were younger than 10 years old. They had no history of staying abroad and were living in Japan. This strains were classified into GR clade (GISAID), 20B clade (Nextstrain) and R.1 lineage (PANGO). As of March 5, 2021, the R.1 lineage have been identified in 305 samples and dominantly observed in the USA (44%, 135 / 305) and Japan (28%, 84 / 305) from the GISAID database. During the period between October 26, 2020 and February 23, 2021, the frequency of the R.1 lineage was 0.97% (84 / 8,629) of the total confirmed data in Japan and 0.15% (135 / 90,450) in the USA. Although SARS-CoV-2 R.1 lineage was not globally predominant as of March 2021, further analysis is needed to determine whether R.1 variant will disappear or expand in the future.