Abstract
The emergence of new variants of the SARS-CoV-2 virus during the COVID-19 pandemic has prompted significant developments in the understanding, monitoring, and response to these strains. This comprehensive review focuses on two prominent variants of interest (VoI), XBB. 1.5 (Kraken) and XBB.1.16 (“Arcturus”), along with seven variants under observation (VuM), including EG.5. The World Health Organization (WHO) identified these variants in July 2023, highlighting EG.5's noteworthy rise in prevalence. EG.5, also known as “Eris,” has exhibited an increased effective reproductive rate, prompting concerns about its contagiousness and immune evasion capabilities. With an altered spike protein in the Receptor-Binding Domain (RBD), EG.5 shares similarities with XBB.1.5 but surpasses it in prevalence, constituting 20% of COVID-19 cases in the United States by late August. EG.5's subvariant, EG.5.1, poses challenges with mutations like Q52H and F456L, contributing to its ability to bypass neutralizing antibodies. The global distribution of SARS-CoV-2 variants presents a dynamic landscape, with XBB.1.16 and other strains gaining prominence. The advent of the BA.2.86 variant further complicates the scenario, with its notable spread in regions lacking robust viral surveillance. A thorough analysis of mutations reveals the evolving nature of the Omicron variant, with distinct amino acid changes characterizing XBB.1.5, XBB.1.16, and EG.5. The WHO designates EG.5 as a “variant of interest” due to its increased contagiousness and potential immune evasion, emphasizing the need for vigilant monitoring. The risk assessment of EG.5 underscores its rapid development and growing prevalence globally. While booster vaccines targeting XBB.1.5 are in development, antiviral medications like nirmatrelvir/ritonavir (Paxlovid) continue to exhibit efficacy. In the context of the evolving variants, the FDA has granted emergency use authorization for updated COVID-19 vaccines targeting circulating strains, reflecting the adaptability of vaccination strategies to address emerging challenges. This comprehensive overview provides a nuanced understanding of the diverse Omicron subvariants, their global impact, and the ongoing efforts to combat their spread through vaccination and therapeutic interventions.
Graphical Abstract
