Fig. 4: Distribution of anti-RBD antibody titres, neutralisation and inhibition capacity results following a two-dose Pfizer-BioNTech BNT162b2 immunisation compared between those with and without evidence of subsequent infection in an older-adult population.

Centre line: median; box limits: first and third quartile; whiskers: 1.5*IQR; points: outliers. SARS-CoV-2 PCR positivity over 6 months post-second dose; no (green), yes (brown) (a) n = 192 individual participants. Higher IgG titres immediately after vaccination are associated with reduced odds of PCR positivity over the following 6 months. (p = 0.002). For each 10-unit increase in Abbott IgG CMIA titre, the odds of PCR positivity decrease by 9% (OR 0.91, 95% CI 0.86–0.97). b n = 182 individual participants. Data from this study do not provide evidence for a linear association between log anti-RBD titres immediately after vaccination and odds of PCR positivity over the following 6 months (p = 0.5). c n = 184 individual participants Data from this study provide, at best, very weak evidence that a higher pseudovirus neutralisation % immediately after vaccination might be associated with slightly lower odds of PCR positivity over the following 6 months (OR per unit change in neutralisation%: 0.993, 95% CI 0.985 to 1) p = 0.07). d n = 183 individual participants. Data from this study do not provide evidence for a linear association between RBD antibody-binding inhibition % immediately after vaccination and odds of PCR positivity over the following 6 months (p = 0.1).