Fig. 5: Determination of the increase in antibody breadth.

a, b, Heat maps showing the IC₅₀ values of clonal pairs of antibodies obtained from persisting clones at 5 months after the second vaccine dose and 1 month after the third dose (a) and clones and singlets found 1.3 months after the second dose⁶ and newly detected (either as a unique clone or singlet) 1 month after the third vaccine dose (b) against the indicated mutant and variant SARS-CoV-2 pseudoviruses. Beta-RBD and Delta-RBD indicate K417N/E484K/N501Y and L452R/T478K SARS-CoV-2 spike proteins, respectively. The heat map range from 0.1 to 1,000 ng ml⁻¹ is represented by white to red. The antibody classes in a and b were determined by competition BLI. c, Graphs showing the neutralization activity of the antibodies shown in a and b against WT, Beta-RBD (L452R/T478K) and Omicron BA.1, comparing n = 38 monoclonal antibodies isolated at 1.3 months after the second vaccine dose and n = 36 monoclonal antibodies isolated 1 month after the third vaccine dose. Red bars and numbers indicate geometric mean values. Statistical significance was determined using the two-tailed Mann–Whitney test. P values are as indicated. d, Ring plots showing the fraction of neutralizing (IC₅₀ < 1,000 ng ml⁻¹) and non-neutralizing (IC₅₀ > 1,000 ng ml⁻¹) antibodies (represented by light grey and dark grey, respectively) for the indicated SARS-CoV-2 pseudoviruses. The numbers in the inner circles correspond to the numbers of antibodies tested.