Figure 2. Neutralization of XBB.1.16 by bivalent-vaccinated, 3-dose-vaccinated, and BA.4/5 convalescent sera.

Neutralizing antibody titers of three different cohorts of human sera against lentiviral pseudotypes bearing XBB.1.16 or other S proteins of interest were determined.

HCWs receiving 3 doses of monovalent mRNA vaccine plus 1 dose of bivalent mRNA vaccine (n = 14) (A), HCWs receiving 3 doses of monovalent mRNA vaccine (n = 15) (C and D), and first responders and household contacts that tested positive for COVID-19 during the BA.4/5 wave of infection (E and F) are all from Columbus, OH (USA). Bars represent geometric means with 95% confidence intervals. Geometric mean NT₅₀ values are displayed for each subvariant on the top (A, C, and E). Heatmap depictions of neutralizing antibody titers were made for individuals in the (B) bivalent-vaccinated, (D) 3-dose-vaccinated, and (F) BA.4/5-wave-infected cohorts. Statistical significance in (A), (C), and (E) was determined using log₁₀-transformed NT₅₀ values to better approximate normality. Comparisons between multiple groups were made using a one-way ANOVA with Bonferroni post-test, with all compared to BA.4/5 in each panel. Dashed lines represent the assay’s limit of detection, i.e., 40 (the lowest dilution factor of serum samples). Asterisk in (B) indicates the individual infected by SARS-CoV-2 within 6 months before the sera sample collection, and asterisks in (F) indicate the individuals who had received three doses of mRNA vaccine before infection. p values are displayed as “ns” p > 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001.