Figure 6.

Effect of a third dose of an mRNA vaccine on anti‐SARS‐CoV‐2 antibodies and neutralising activity. (a) Titres of IgG antibodies against different full‐length recombinant SARS‐CoV‐2 proteins and their delta variants were measured in 32 SOT recipients using an ELISA before and after a third ‘booster’ dose of a COVID‐19 mRNA vaccine. (b, d) Neutralising activity before and after a third ‘booster’ dose of a COVID‐19 mRNA vaccine in the peripheral blood of the same SOT recipients. Green, orange and red areas indicate different degrees of inhibition (green, > 90%; orange, 30–89%; red, < 30%). (c) Titres of post‐booster IgG antibodies against the original anti‐SARS‐CoV‐2 RBD and S1 proteins vs. their omicron variants. Bars indicate median levels. Differences between groups were analysed for statistical significance (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001) using the Mann–Whitney U‐test.