Fig. 2: Binding assays.

IgG antibodies specific to; a–c SARS-CoV-2 (spike [S], receptor-binding domain [RBD], nucleocapsid [N]), d, e SARS-CoV-1 S, MERS-CoV S, f–i HCoV-OC43 S, HCoV-HKU1 S, HCoV-229E S, HCoV-NL63 S, were measured using an MSD technology platform customised array. Sera analysed were from vaccinees (post-prime and post-boost), asymptomatic (mean 27 days post-PCR positive test, range 22–33 days) and mild COVID-19 convalescent sera (mean 29 days post-symptom onset, range 18–40 days) and a cohort of prepandemic sera collected between 2014 and 2018 negative for SARS-CoV-2 (negatives). Data are displayed as calculated concentrations which use an MSD standard reference curve to interpret arbitrary units (AU). Statistical difference between the groups was performed using a two-tailed Kruskal–Wallis one-way ANOVA with Dunn’s post-test for multiple comparisons made to compare all groups (significant adjusted P values are displayed). Vaccinees post-prime n = 11; vaccinees post-boost n = 25; negatives n = 103; asymptomatic COVID-19 convalescents n = 11; mild COVID-19 convalescents n = 62. The dashed lines in a–c show the cut-offs determined as the mean of negatives +3 SD. Samples were run in monoplicate (convalescent samples) or duplicates (vaccine samples). j Inhibition analysis between ACE2 and recombinant spike from the designated homotypic and heterotypic lineages. Sera derived from individuals receiving prime or boost vaccination: post-prime n = 11, post-boost n = 18–25 dependent on spike variant. Differences between B and other variants in post-prime and post samples were tested using a Friedman statistical test with Dunn’s multiple comparison test (significant P values are displayed on lines linking B to variant). A two-tailed Mann–Whitney U test was used to compare post-prime and post boost groups for each variant. P values are displayed on the boost panel, immediately above each variant and are italicized. Plots show median with error bars indicating ± intraquartile range) (IQR). ACE2 inhibition assay samples were run in monoplicate.