Figure 1.

Immune response of kidney transplant recipients (KTRs; n = 46) and close household contacts (CHCs; n = 46) to 2 doses of coronavirus disease 2019 (COVID-19) vaccine. KTR and CHC were concurrently vaccinated with the BNT162b2 or ChAdOx1 vaccine. Blood samples collected at baseline, 3 weeks after dose 1, and 3 weeks after dose 2. (a) Log-scale longitudinal comparison of serum spike-specific antibody titers, reported as area under the curve (AUC) units. Circles represent AUC individual participant values, with mean value denoted by black bars. (b) Log-scale comparison of serum anti–severe acute respiratory syndrome coronavirus 2 (αSARS-CoV-2) receptor-binding domain (RBD) IgG titers 3 weeks after dose 2 in KTRs and CHCs. Results below the detection threshold are plotted as 0.4 U/ml and marked with a dashed line. The percentage of individuals above the detection limit is indicated. (c) Serological neutralization end point cutoff titers in KTRs and CHCs. Data points represent the highest serum dilution factor that yielded 50% inhibition of live virus (Wuhan) infection. Twenty was the minimum dilution tested for all samples, and the percentage of individuals achieving a neutralization titer of ≥20 is indicated. Individuals who did not achieve neutralization at a dilution factor of ≥20 were considered negative and ascribed a value of zero, marked with a dashed line. (d) Vaccine-induced interferon-γ (IFN-γ)–secreting T-cell response. Isolated peripheral blood mononuclear cells (PBMCs) were stimulated for 18 hours with spike glycoprotein-derived peptides and the frequency of IFN-γ–secreting cells measured as spot-forming units (SFUs) by enzyme-linked immunoabsorbent spot assay. SFUs at baseline were subtracted from SFUs 3 weeks after dose 2 to determine the change in spike-reactive, IFN-γ–secreting T-cell frequencies in response to vaccination. Differences between groups tested using the 2-tailed Mann-Whitney test. NS, not significant. ∗∗∗∗P < 0.0001. ΔIFN-γ, change in interferon-γ.