Abstract

The SARS-CoV-2 Omicron variant and its subvariants have posed significant challenges to global public health since their emergence in late 2021. This comprehensive review examines the epidemiological trends, clinical impacts, and public health challenges associated with Omicron subvariants, with a focus on high-density populations such as Bangladesh. The review highlights the evolution of Omicron subvariants, including BA.1, BA.2, BA.4/BA.5, XBB, BQ.1, EG.5, and JN.1, emphasizing their increased transmissibility, immune evasion, and varying severity. Despite lower intrinsic severity compared to Delta, Omicron's rapid spread has strained healthcare systems, particularly in regions with limited resources. In Bangladesh, Omicron subvariants such as XFG, XFC, and NB.1.8.1 have driven recent surges, with test positivity rates peaking at 20% in June 2025. The review underscores the persistent threat of these subvariants, especially among vulnerable populations like the elderly, and the critical need for enhanced genomic surveillance, vaccination campaigns, and adaptive public health strategies. Some of the key challenges include vaccine hesitancy, healthcare infrastructure limitations, and socioeconomic barriers. The findings advocate for robust global cooperation, updated vaccines, and targeted interventions to mitigate the ongoing impact of Omicron subvariants in high-risk settings.

Key words: SARS-CoV-2 subvariants, Omicron, Epidemiology, XBB, XFG, Health risk,