A. Concordance between ELLA and qTACT assays for IFN-γ/IFNG. For n = 91 subjects, IFN-γ secretion was quantified by ELLA (x-axis) and IFNG mRNA by qTACT (y-axis). Colors on their COVID-19 and vaccination statuses (see legend). The dashed lines represent thresholds for each assay. B-C. Quantification CXCL10 mRNA using dqTACT (B) or IFN-γ protein section using ELLA (C) in subjects enrolled in the CombiVacS trial. All subjects received a first dose of ChAdOx1s from AstraZeneca (Dose 1 (AZ)). The patients were then divided into two groups and received either a second placebo dose (Dose 1 (AZ) + Dose 2 (placebo)) or a second dose of BNT162b2 from Pfizer (Dose 1 (AZ) + Dose 2 (Pfizer)). The dqTACT assay was completed as shown in Fig. 1A (bottom). Comparisons show significance for the Wilcoxon rank sum two-sided test. For (B), naive, N = 13; dose 1 (AZ), N = 142, dose 1 (AZ) + dose 2 (placebo), N = 49; dose 1 (AZ) + dose 2 (Pfizer), N = 92 biologically independent samples. For (C), naive, N = 43; dose 1 (AZ), N = 155, dose 1 (AZ) + dose 2 (placebo), N = 52; dose 1 (AZ) + dose 2 (Pfizer), N = 99 biologically independent samples.