Figure 1. Anti-Spike IgG Responses against Omicron BA.4 and BA.5 Subvariants before and after Bivalent mRNA Booster in Patients Undergoing Hemodialysis.

Anti-spike IgG concentrations 6 and 2 weeks before, as well as 2 and 4 weeks after, fifth messenger RNA (mRNA) vaccination in patients with previous B.1.1.529 (omicron) breakthrough infection (open circles) and those with no previous omicron breakthrough infection (triangles) are shown (Panel A). Connecting lines between the time points indicate matched serum samples. The dashed horizontal line indicates the lower limit of detection (31 binding antibody units [BAU] per milliliter) in the detection system. Neutralizing activities are presented as serum dilutions for half-maximal infection-neutralization capacities normalized to 10⁷ viral RNA copies (50% inhibitory concentration [IC₅₀]) for omicron BA.4 (Panel B) and BA.5 (Panel C). The anti-spike IgG antibody avidities are shown as relative percentages for three time points (Panel D). The median value (horizontal line) and interquartile range (whiskers) are shown. P values are given for comparison of the dependent variables between different time points for each group. For comparison between patients with previous omicron breakthrough infection and those with no previous omicron breakthrough infection at each time point, one asterisk denotes P<0.05, two asterisks P<0.01, and three asterisks P<0.001.