Figure 2.

Neutralizing activity of sera from triple-vaccinated individuals against ancestral B.1, Delta and Omicron BA.1, BA.2, BA.4 and BA.5. (A) Comparison of NT50 between all strains. The infecting strain is indicated on the x-axis and with color codes: blue open circles = B.1, purple open triangles = Delta, gold open hexagons = Omicron BA.1, pink open hexagons = Omicron BA.2, orange open hexagons = Omicron BA.4 and burgundy open hexagons = Omicron BA.5. The dotted line represents the 1:40 serum dilution cut-off. Sera which did not neutralize SARS-CoV-2 at the 1:40 dilution were considered non-neutralizing. The proportion of non-neutralizing sera is indicated above each data set. (B) Correlation of NT50 between the tested strains. The Spearman correlation coefficient (r) is indicated in each panel. (C) NT50 for a subset of sera assessed using Luciferase-tagged HIV-1-ΔenvΔnef-Spike pseudotypes. All infections were performed in triplicate. (D) Anti-Spike, anti-RBD and anti-NTD antibody levels in vaccinee sera. Antibody levels against Spike (purple), the Receptor Binding Domain (RBD) (pink) or the N-terminal domain (NTD) (blue) of Spike were measured in vaccinee sera using the MSD V-plex platform for SARS-CoV-2. Antibody levels are reported as arbitrary units. (E) Ratios of NT50 to anti-S, (left panel), anti-RBD (middle panel) and anti-NTD (right panel) antibody levels. A Friedman test followed by a Dunn’s multiple comparison post-hoc test was used for comparisons between three or more groups (panels (A,C–E)). p-values < 0.05 were considered significant. *: p < 0.05; **: p < 0.01; ***: p < 0.001.