Fig. 2
Dynamics of pseudovirus neutralization profiles in uninfected older adults six months after booster vaccination. a–c The longitudinal dynamics of 50% pseudovirus neutralization titers (NT50) against SARS-CoV-2 variants—D614G, BA.5, XBB.1.5, JN.1, KP.2, KP.3, KP.3.1.1, and XEC—were assessed in uninfected older adults during a six-month follow-up period after receiving a booster dose of either the Tri‑XBB.1.5 vaccine (a), Bi‑Omi‑XBB vaccine (b), or Tetra‑XBB.1 vaccine (c). d A radar plot was generated to illustrate the tropism and breadth of neutralizing antibody responses induced by the Tri‑XBB.1.5 vaccine, Bi‑Omi‑XBB vaccine, and Tetra‑XBB.1 vaccine across the tested variants during the six-month follow-up. In the boxplots (a–c), horizontal bars and boxes represent the median and interquartile range (IQR) NT50, respectively; whiskers reference 95% confidence intervals (CIs). The gray circles represent individual data points, with connecting lines representing longitudinal samples from the same participants. The dotted line represents the assay detection threshold (NT50 = 30). The fold change in geometric mean titers (GMTs) between time points is indicated in brackets. In the radar plots, the vertical line represents each variant or spoke, and the spokes are evenly distributed around the circle. Each horizontal line along a vertical spoke represents the GMT at a tenfold dilution, with the value closest to the center being 1 (100) and farthest from the center being 100,000 (105). A two-sided Friedman test with false discovery rate (FDR) correction was employed for within-vaccine longitudinal comparisons (three time points per vaccine). A two-tailed Kruskal‒Wallis test with the FDR was used to compare differences in neutralizing antibody titers among vaccines at different time points. A p value less than 0.05 was considered statistically significant. P values for the differences between neutralization titers across different time points for each vaccine are denoted by asterisks (*p < 0.05, **p < 0.01, ***p < 0.001) in (a), (b), and (c), and only significant differences are displayed in the figure. P values for comparisons between vaccines at each time point are color-coded and shown at the top in (a), (b), and (c). NT50 values are derived from a single experiment with two technical replicates
