Figure 6.

Avidity profile of antibodies from individuals of the “vaccination” and “breakthrough infection” groups against Wuhan-1 antigens. Immunoglobulin (Ig) G, IgM, and IgA avidity against wild-type (WT) spike or WT receptor-binding domain (RBD) antigens is shown for the vaccination (n = 40) (A) and breakthrough infection (n = 25) (B) groups, expressed as the avidity index (AI). WT refers to the sequence of the original Wuhan-Hu-1 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) isolate. Analyses were performed using Mann-Whitney U test for comparisons among different groups (A) and a parametric paired t test for comparing prebreakthrough and postbreakthrough infection responses (B). *P < .03; **P < .002; ***P < .001. The average fold change in AI occurring with breakthrough infection is indicated for each Pre-Post pair, represented by dots. Each symbol represents a single participant; bars, geometric mean; and error bars, geometric standard deviations. Samples with an AI <35, indicated by the dotted line, are considered to have low avidity.