Identification of B.1.346 Lineage of SARS-CoV-2 in Japan: Genomic Evidence of Re-entry of Clade 20C.

SARS-CoV-2 whole-genome sequencing of samples from COVID-19 patients is useful for informing infection control. Datasets of these genomes assembled from multiple hospitals can give critical clues to regional or national trends in infection. Herein, we report a lineage summary based on data collected from hospitals located in the Tokyo metropolitan area. We performed SARS-CoV-2 whole-genome sequencing of specimens from 198 patients with COVID-19 at 13 collaborating hospitals located in the Kanto region. Phylogenetic analysis and fingerprinting of the nucleotide substitutions were performed to differentiate and classify the viral lineages. More than 90% of the identified strains belonged to Clade 20B, which has been prevalent in European countries since March 2020. Only two lineages (B.1.1.284 and B.1.1.214) were found to be predominant in Japan. However, one sample from a COVID-19 patient admitted to a hospital in the Kanto region in November 2020 belonged to the B.1.346 lineage of Clade 20C, which has been prevalent in the western United States since November 2020. The patient had no history of overseas travel or any known contact with anyone who had travelled abroad. Consequently, the Clade 20C strain belonging to the B.1.346 lineage appeared likely to have been imported from the western United States to Japan across the strict quarantine barrier. B.1.1.284 and B.1.1.214 lineages were found to be predominant in the Kanto region, but a single case of the B.1.346 lineage of clade 20C, probably imported from the western United States, was also identified. These results illustrate that a decentralized network of hospitals offers significant advantages as a highly responsive system for monitoring regional molecular epidemiologic trends.

Very late stent thrombosis occurring simultaneously in sirolimus-eluting stents and bare-metal stent in three different coronary vessels.

A 36-year-old male was diagnosed with acute inferior myocardial infarction (MI). Emergent coronary angiography (CAG) revealed an occlusive lesion in the distal segment of the right coronary artery (RCA). The proximal and distal sites of the lesion were treated with a bare-metal stent (BMS) and a sirolimus-eluting stent (SES), respectively. Nine days later, he underwent elective percutaneous coronary intervention (PCI). Two SESs were implanted for the stenotic lesion in the left anterior descending artery (LAD), in addition to one SES for the mid-stenotic lesion in the left circumflex artery (LCX). Nine months after PCI, follow-up CAG revealed no restenosis at any stent-implanted site. Two years and 4 months after PCI, he was admitted to our hospital because of acute anterior MI. Emergent CAG revealed total thrombotic occlusion in the in-stent proximal site of LAD. Moreover, thrombotic lesions were also observed in in-stent sites: in both BMS of RCA and SES of LCX. He underwent intracoronary aspiration thrombectomy and plain old balloon angioplasty for LAD using intra-aortic balloon pumping. PCI for the thrombotic lesions in RCA and LCX was not performed. Seventeen days after the stent thrombosis, CAG revealed the complete disappearance of thrombi in LAD, LCX, and RCA.