Cellular and Humoral Responses to Recombinant and Inactivated SARS-CoV-2 Vaccines in CKD Patients: An Observational Study.

Background: It remains unclear what B cell and humoral responses are mounted by chronic kidney disease (CKD) patients in response to recombinant and inactivated SARS-CoV-2 vaccines. In this study, we aimed to explore the cellular and humoral responses, and the safety of recombinant and inactivated SARS-CoV-2 vaccines in CKD patients.

Methods: 79 CKD and 420 non-CKD individuals, who completed a full course of vaccination, were enrolled in the study. Adverse events (AEs) were collected via a questionnaire. Cellular and humoral responses were detected at 1, 3, and 6 months, including IgG antibody against the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein (anti-RBD-IgG), neutralizing antibodies (NAbs), the positive rate of NAbs and anti-RBD-IgG, RBD-atypical memory B cells (MBCs) (CD3 - CD19 + RBD + CD21 - CD27-), RBD-activated MBCs (CD3 - CD19 + RBD + CD21 - CD27+), RBD-resting MBCs (CD3 - CD19 + RBD + CD21 + CD27+), and RBD-intermediate MBCs (CD3 - CD19 + RBD + CD21 + CD27-).

Results: We found no differences in the positivity rates of NAbs (70.89% vs. 79.49%, = 0.212) and anti-RBD IgG (72.15% vs. 83.33%, = 0.092) between the CKD and control groups. A total of 22 CKD individuals completed the full follow-up (1, 3, and 6 months). Significant and sustained declines were found at 3 months in anti-RBD IgG (26.64 BAU/mL vs. 9.08 BAU/mL, < 0.001) and NAbs (161.60 IU/mL vs. 68.45 IU/mL < 0.001), and at 6 months in anti-RBD IgG (9.08 BAU/mL vs. 5.40 BAU/mL, = 0.064) and NAbs (68.45 IU/mL vs. 51.03 IU/mL, = 0.001). Significant differences were identified in MBC subgroups between CKD patients and healthy controls, including RBD-specific atypical MBCs (60.5% vs. 17.9%, < 0.001), RBD-specific activated MBCs (36.3% vs. 14.8%, < 0.001), RBD-specific intermediate MBCs (1.24% vs. 42.6%, < 0.001), and resting MBCs (1.34% vs. 22.4%, < 0.001). Most AEs in CKD patients were mild (grade 1 and 2) and self-limiting. One patient with CKD presented with a recurrence of nephrotic syndrome after vaccination.

Conclusions: The recombinant and inactivated SARS-CoV-2 vaccine was well-tolerated and showed a good response in the CKD cohort. Our study also revealed differences in MBC subtypes after SARS-CoV-2 vaccination between CKD patients and healthy controls.