The epidemiology and phylogenetic trends of Omicron subvariants from BA.5 to XBB.1 in Taiwan

Background: Omicron, a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, entered Taiwan at the end of 2021. The Taiwanese government ended its ''zero-COVID'' policy in March 2022. Multiple coronavirus disease 2019 (COVID-19) outbreaks began in April 2022. We m...

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Main Authors: Jih-Jin Tsai, Shyh-Shin Chiou, Po-Chih Chen, Chun-Hong Chen, Ping-Chang Lin, Ching-Yi Tsai, Wan-Long Chuang, Shang-Jyh Hwang, Inn-Wen Chong, Li-Teh Liu
Format: Article
Language:English
Published: Elsevier 2024-11-01
Series:Journal of Infection and Public Health
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Online Access:http://www.sciencedirect.com/science/article/pii/S1876034124002909
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Summary:Background: Omicron, a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, entered Taiwan at the end of 2021. The Taiwanese government ended its ''zero-COVID'' policy in March 2022. Multiple coronavirus disease 2019 (COVID-19) outbreaks began in April 2022. We monitored the replacement of Omicron subvariants after BA.1/BA.2 and analyzed their correlation with COVID-19 outbreaks. Methods: We collected SARS-CoV-2 real-time qRTPCR-positive nasopharyngeal swabs from Kaohsiung Medical University Hospital (KMUH), Kaohsiung City, Taiwan, and performed sequencing for specimens exhibiting a cytopathic effect in Vero E6 cells to determine their clades and lineages. We analyzed the medical records of COVID-19 patients and identified hospitalization risk factor(s). We retrieved SARS-CoV-2 sequences identified in Taiwan from GISAID and analyzed their correlation with COVID-19 data from the Taiwan Centers for Disease Control. Results: We analyzed the phylogenesis of KMUH-47 to KMUH-104 (SARS-CoV-2 isolates identified herein) and all of the Omicron subvariants from BA.5 to XBB.1 (n = 1930). Age and comorbidities were hospitalization risk factors. Men generally exhibited a greater fatality rate than women. COVID-19-related deaths predominantly occurred in individuals over 70 years old. The COVID-19-related case fatality rate increased as nucleotide (NT) and amino acid (AA) substitutions increased. The number of COVID-19-related cases and deaths progressively decreased with each outbreak between August 2022 and October 2023. Conclusion: Hospitalization was associated with age and the presence of comorbidities. COVID-19-related fatality was linked to sex, age, and the accumulation of NT and AA substitutions in emerging Omicron subvariants.
ISSN:1876-0341