Less neutralization evasion of SARS-CoV-2 BA.2.86 than XBB sublineages and CH.1.1

The highly mutated BA.2.86, with over 30 spike protein mutations in comparison to Omicron BA.2 and XBB.1.5 variants, has raised concerns about its potential to evade COVID-19 vaccination or prior SARS-CoV-2 infection-elicited immunity. In this study, we employ a live SARS-CoV-2 neutralization assay to compare the neutralization evasion ability of BA.2.86 with other emerged SARS-CoV-2 subvariants, including BA.2-derived CH.1.1, Delta-Omicron recombinant XBC.1.6, and XBB descendants XBB.1.5, XBB.1.16, XBB.2.3, EG.5.1 and FL.1.5.1. Our results show that BA.2.86 is less neutralization evasive than XBB sublineages. Among all the tested variants, CH.1.1 exhibits the greatest neutralization evasion. In comparison to XBB.1.5, the more recent XBB descendants, particularly EG.5.1 and FL.1.5.1, display increased resistance to neutralization induced by parental COVID-19 mRNA vaccine and a BA.5-Bivalent-booster. In contrast, XBC.1.6 shows a slight reduction but remains comparable sensitivity to neutralization when compared to BA.5. Furthermore, a recent XBB.1.5-breakthrough infection significantly enhances the breadth and potency of cross-neutralization. These findings reinforce the expectation that the upcoming XBB.1.5 mRNA vaccine would likely boost the neutralization of currently circulating variants, while also underscoring the critical importance of ongoing surveillance to monitor the evolution and immune evasion potential of SARS-CoV-2 variants.