Comparison of immunogenicity between BNT162b2 and ChAdOx1 SARS-CoV-2 vaccines in a large haemodialysis population

Background

Limited data exists on the immunogenicity of vector-based SARS-CoV-2 vaccines in patients with kidney disease. Given their use in over 180 countries, such data is of upmost importance to inform policy on optimal vaccination strategies. This study compares the immunogenicity of BNT162b2 with ChAdOx1 in patients receiving haemodialysis.

Methods

1021 patients were screened for spike protein antibodies (anti-S) following 2 doses of either BNT162b2 (n=523) or ChAdOx1 (n=498). 191 patients underwent assessment with T-cell ELISpot assays. 65 health care workers were used as a control group.

Results

Anti-S was detected in 936 (91.2%) of patients post-vaccination. There was no difference in seroconversion rates between infection-naïve patients who received BNT162b2, 248/281 (88.3%), compared with ChAdOx1, 227/272 (83.5%), p=0.11. Anti-S concentrations were higher following BNT162b, 462(152-1171) BAU/ml, compared with ChAdOx-1 79(20-213) BAU/ml, p<0.0001. Immunosuppression was associated with failure to seroconvert (p<0.0001); whilst being active on the transplant wait list was a predictor for seroconversion (p=0.02).

Only 73 (38.2%) of patients had detectable T-cell responses post-vaccination, with no proportional difference between infection-naïve patients who received BNT162b2, 2/19 (10.5%), versus ChAdOx1, 15/75 (20.0%), p=0.34. There were no quantitative differences in T-cell responses in infection-naïve patients, with a median 2(0-16) SFU/10⁶PBMCs and 10(4-28) SFU/10⁶PBMCs in those receiving BNT162b2 and ChAdOx1 respectively, p=0.35. These responses were significantly weaker compared with healthy controls.

Conclusions

Enhanced immunogenicity was seen with BNT162b2 compared with ChAdOx1, driven by superior humoral responses, with attenuated T-cell responses to both vaccines. Comparative data on clinical efficacy is now required.

Significance Statement

Limited data exist on the immunogenicity of vector-based SARS-CoV-2 vaccines in patients with kidney disease. Given their use in over 180 countries worldwide, such data are of upmost importance to inform policy on optimal vaccination strategies. This study compares the immunogenicity of BNT162b2 (n=523) against the adenovirus vector vaccine, ChAdOx1 (n=498), in 1021 haemodialysis patients. In infection-naïve patients, overall seroconversion rates were comparable, however, spike protein antibody concentrations were significantly higher following BNT162b2. No difference in T-cell responses was seen, however, all naïve patients had weaker responses compared with healthy controls. Equivalent attenuated cellular responses to both vaccines, with greater humoral responses to BNT162b2, suggests BNT162b2 has superior immunogenicity in this patient population, with data on clinical efficacy required.