Genomic analysis of three SARS-CoV-2 waves in west Sumatra: Evolutionary dynamics and variant clustering

Background: The Severe Acute Respiratory Syndrome Coronavirus 2 virus (SARS-CoV-2) has been undergoing evolutionary changes to improve its ability to thrive within human hosts, leading to the emergence of specific variants associated with subsequent waves of the coronavirus diseases 2019 (COVID-19) pandemic. Indonesia has grappled with the effects of this pandemic and subsequent waves affecting various regions, including West Sumatra. Although located outside Java island epicenter, West Sumatra experienced significant COVID-19 transmission, especially during the third wave in early 2022. Objective: This study aimed to investigate the genetic evolution and epidemiological dynamics of SARS-CoV-2 variants in West Sumatra throughout the three pandemic waves. Methods: We conducted a genotyping study retrospectively using 278 COVID-19 patient samples from 2020 to 2022. The Real-Time Quantitative Reverse Transcription PCR (RT-qPCR) was used for screening, and whole-genome sequence analysis was conducted through the Illumina MiSeq instrument. Result: The analysis revealed distinct patterns in the prevalence of viral lineages across the waves. The initial wave was predominated by clade 20A (77,4 %) especially lineage B.1.466.2 (50 %). The second wave was marked by a significant emergence of the Delta variant (72,5 %), particularly lineage AY.23 (81,1 %), originating from India, with subsequent local evolution leading to the formation of distinct clusters. We found that about 96,7 % of the third wave variant was dominated by Omicron variants, especially the generation of lineages BA.1 and BA.2, demonstrating widespread global dissemination and local variant development. Phylogenetic analysis indicated a close relatedness of West Sumatra variants to those from Malaysia and other parts of Indonesia, highlighting regional transmission dynamics and potential sources of variant introductions. Conclusion: This study has identified unique variant clusters within each wave, suggesting distinct evolutionary pathways and local adaptations. These findings provide valuable insights into the genomic landscape of SARS-CoV-2 in West Sumatra and emphasize the crucial role of ongoing genomic surveillance in tracking viral changes and guiding public health measures.