Fig. 2. Immune evasion of XBB.1.5.

Neutralization assays were performed with pseudoviruses harboring the S proteins of B.1.1, BA.1, BA.5, XBB.1, and XBB.1.5. The following sera were used: (A) fourth-dose vaccine sera collected one month after the fourth-dose monovalent vaccine (15 donors), (B) BA.1 bivalent vaccine (20 donors), and (C) BA.5 bivalent vaccine (21 donors). Assays for each serum sample were performed in triplicate to determine the 50% neutralization titer (NT₅₀). Each dot represents one NT₅₀ value, and the geometric mean and 95% CI are shown. Statistically significant differences were determined by two-sided Wilcoxon signed-rank tests. The P values versus B.1.1 are indicated in the panels. The horizontal dashed line indicates the detection limit (120-fold). Red numbers indicate decreased and increased NT₅₀s. Information on the convalescent donors is summarized in Supplementary data 2.