Comparison of the Immunogenicity of ChAdOx1 nCoV-19 Vaccine against the Wild-Type and Delta Variants in Kidney Transplant Recipients and Healthy Volunteers.

Little is known about immunogenicity after ChAdOx1 nCov-19 vaccination after transplantation. We assessed the vaccine response by antibody testing, surrogate neutralization test (sVNT) against wild-type (WT) and delta variant (DT), and T cell assay in 83 kidney transplant recipients (KTRs) and 52 healthy volunteers (HVs). For KTRs, a positive anti-RBD antibody was seen in 2.8% after one dose and 15.7% after two doses of the vaccine. After two doses, the positivity rate by sVNT was equal (4.9% each, for WT and DT), and was 13.4% by T cell response. Post two doses, KTRs had significantly lower geometric mean titer than HVs [1.93 (95% CI: 1.39-2.69) VS. 248.3 (95% CI: 203.7-302.6) BAU/mL, respectively, p 3 mg of tacrolimus significantly associated with negative seroconversion [RR = 0.38 (95% CI, 0.17-0.85, p=0.018) and RR = 0.16 (95% CI, 0.37-0.73, p=0.018), respectively. The vaccine was safe and well-tolerated but the immune response after the two doses of ChAdOx1 nCov-19 vaccine in KTRs was very low.
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