ABSTRACT
Background Patients on maintenance hemodialysis (MHD) are at high risk of infection with SARS-Cov-2 and death due to COVID-19. This vulnerable population has been prioritized for vaccination, but the level of protection achieved in these immunocompromised patients is unclear. Objectives To evaluate the protection of MHD patients against COVID-19 after 2 doses (2D) of BNT162b2, and the safety and impact on immune responses of a 3 rd dose (3D). Design Prospective observational. Setting, Patients, intervention and measurements REIN national registry was used to compare the severity of 1474 cases of COVID-19 diagnosed in MHD patients after 0, 1 or 2 doses of mRNA vaccine. Anti-spike receptor binding domain (RBD) IgG and interferon gamma-producing CD4+ and CD8+ specific-T cells were measured after 2D and 3D of BNT162b2 in a monocentric cohort of 75 MHD patients. Results Vaccination reduced disease severity but 11% of MHD patients infected after 2D still died. Tolerance to 3D of BNT162b2 was excellent. MHD patients with humoral response similar to healthy volunteers after 2D did not generate more immune effectors after 3D and had more side effects. In contrast, 2/3 of MHD patients with suboptimal response after 2D reached optimal titer of anti-RBD IgG and/or developed spike-specific CD8+ T cells after 3D. Presence of spike-specific CD4+ T cells after 2D was associated with response to 3D in multivariate analysis (OR=4.80 [1.23−21.54]; p=0.029). Limitations Limited number of patients injected with 3D. Conclusion Standard scheme of vaccination provides insufficient protection to some MHD patients. Anti-RBD IgG and specific CD4+ T cells should be measured after 2D. Among patients with suboptimal humoral response, those with specific CD4+ T cells could benefit of a 3 rd dose of vaccine. Registration NCT04881396 Funding Source None