Fig. 4. Relationship between post-vaccination anti-S IgG/A/M antibody ratio, percent naive CD8+ T cells, and age.

a Correlation between age and post-vaccine anti-Spike IgG/A/M antibody ratio, coloured according to frequency of naive (CD45RA+CD27+) CD8+ T cells present in the peripheral blood of the individuals. b percent of cytokine positive CD4+T after PBMC stimulation with S peptide as determined by intracellular cytokine staining, coloured according to anti-S IgG/A/M antibody ratio normalised to mean 0 and variance ±1. Data presented on y axis is normalised including log₂ transformation and adjustment for baseline and post-vaccination covariates (sex, BMI category, pre-vaccine SARS-CoV-2 serostatus, vaccine type, vitamin D randomisation, inter-vaccine days, and days post second vaccine), p values derived using linear regression for general linear models with adjustments for the same covariates, all q < 0.1. Trend line indicates Pearson correlation (R-statistic).