Fig. 2: Distributions and change in paired SARS-CoV-2 antibody titres and inhibition capacity pre- and post-vaccination with a two-dose Pfizer-BioNTech BNT162b2 regimen in a population of older adults, London, UK, 2021.

The second dose of vaccine was delivered at 12 weeks and antibodies measured 4 weeks later. Results are stratified according to evidence of prior seroconversion (blue) or evidence of seronegative status at baseline (brown). The y-axis (a, b) follows a logarithmic scale. a n = 148 individual participants. Quantified antibody titres targeting the S1 subunit of the RBD were calculated using the Architect IgG Quant II CMIA. Data were censored at <7.1 BAU/ml (reported as not detected) and >5680 BAU/ml (above the upper limit of assay detection). b n = 140 individual participants, anti-RBD antibody titres calculated by in-house hybrid double antigen-binding assay (DABA). c n = 89 individual participants, change in RBD antibody-binding inhibition for 151/192 patients with sufficient sample for testing.