Emergence and Persistent Dominance of SARS-CoV-2 Omicron BA.2.3.7 Variant, Taiwan

Abstract

Since April 2022, waves of SARS-CoV-2 Omicron variant cases have surfaced in Taiwan and spread throughout the island. Using high-throughput sequencing of the SARS-CoV-2 genome, we analyzed 2,405 PCR-positive swab samples from 2,339 persons and identified the Omicron BA.2.3.7 variant as a major lineage within recent community outbreaks in Taiwan.

Keywords: COVID-19; Omicron BA.2.3.7; SARS-CoV-2; Taiwan; coronavirus disease; respiratory infections; severe acute respiratory syndrome coronavirus 2; vaccine-preventable diseases; viruses; zoonoses.

Figure 1

Weekly statistics for confirmed COVID-19 cases in Taiwan and sequenced samples, lineage distribution, and mutation prevalence derived from the NTU-HCH surveillance program, January–June 2022. Graph shows the number of COVID-19 confirmed cases in Taiwan and the sequenced samples from NTU-HCH from January (epidemiologic week 1) to early June (epidemiologic week 23). This figure was constructed using the publicly available data of Taiwan Centers for Disease Control (https://nidss.cdc.gov.tw/nndss/disease?id=19CoV). NTU-HCH, National Taiwan University Hospital–Hsinchu Branch.

Figure 2

Phylogenetic analysis of SARS-CoV-2 sequences based on 1,966 sequences from the NTU-HCH surveillance program in Taiwan and 881 sequences from GISAID (https://www.gisaid.org). Lineages of NTU-HCH strains are annotated in different colors; asterisks (*) represent the collection of a specific lineage with its sublineage. The BA.2.3.7 strains were dominantly circulating in Taiwan from March 2022, highlighted by light blue in the tree. NTU-HCH, National Taiwan University Hospital–Hsinchu Branch.