Background There is scarce evidence on fourth doses of SARS-CoV-2 vaccines in chronic kidney disease (CKD) patients. We have evaluated the humoral response and effectivity of the fourth dose in the CKD spectrum: non-dialysis CKD (ND-CKD), hemodialysis (HD), peritoneal dialysis (PD) and kidney transplant (KT) recipients. Methods This is a prespecified analysis of the prospective, observational, multicentric SENCOVAC study. In patients with CKD who had received a complete initial vaccination and one or two boosters and had anti-Spike antibody determinations 6 and 12 months after the initial vaccination, we analyzed factors associated to persistent negative humoral response and to higher anti-Spike antibody titers as well as the efficacy of vaccination on COVID-19 severity. Results Of 2186 patients (18% KT, 8% PD, 69% HD and 5% ND-CKD), 30% had received a fourth dose. The fourth dose increased anti-Spike antibody titers in HD (P = 0.001) and ND-CKD (P = 0.014) patients and seroconverted 72% of previously negative patients. Higher anti-Spike antibody titers at 12 months were independently associated to repeated exposure to antigen (fourth dose, previous breakthrough infections), previous anti-Spike antibody titers and not being a KT. Breakthrough COVID-19 was registered in 137 (6%) patients, of whom 5% required admission. Admitted patients had prior titers below 620 UI/ml and median values were lower (P = 0.020) than in non-admitted patients. Conclusions A fourth vaccine dose increased anti-Spike antibody titers or seroconverted many CKD patients, but those with the highest need for a vaccine booster (i.e. those with lower pre-booster antibody titers or KT recipients) derived the least benefit in terms of antibody titers. Admission for breakthrough COVID-19 was associated with low anti-Spike antibody titers.

Introduction Patients on hemodialysis are at high-risk for complications derived from coronavirus disease-19 (COVID-19). The present analysis evaluated the impact of a booster vaccine dose and breakthrough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections on humoral immunity three months after the booster dose. Methods This is a multicentric and prospective study assessing IgG anti-Spike antibodies 6 and 9 months after initial SARS-CoV-2 vaccination in patients on hemodialysis that had also received a booster dose before the 6-month assessment (early booster) or between the 6- and 9-month assessments (late booster). The impact of breakthrough infections, type of vaccine, time from the booster and clinical variables were assessed. Results A total of 711 patients (67% male, 67 [20-89] years) were included. Of which, 545 (77%) received an early booster and the rest a late booster. At 6 months, 64 (9%) patients had negative anti-Spike antibody titers (3% of early booster and 29% of late booster patients, p = 0.001). At 9 months, 91% of patients with 6-month negative response had seroconverted and there were no differences in residual prevalence of negative humoral response between early and late booster patients (0.9% vs 0.6%, p = 0.693). During follow-up, 35 patients (5%) developed breakthrough SARS-CoV-2 infection. Antibody titers at 9 months were independently associated to mRNA-1273 booster (p = 0.001), lower time from booster (p = 0.043) and past breakthrough SARS-CoV-2 infection (p<0.001). Conclusions In hemodialysis patients, higher titers of anti-Spike antibodies at 9 months were associated to mRNA-1273 booster, lower time from booster and past breakthrough SARS-CoV-2 infection.

Background and Aims Delayed graft function (DGF) is a common complication after renal transplant. Definitions of DGF are based on analysis of estimated glomerular filtration rate (eGFR) underlying the plasma creatinine fluctuations after renal transplant. We tried to validate an early parameter of DGF in a renal transplant population based on the kinetic estimation of glomerular filtration rate, since this formula adds a quantitative dimension to the assessment of kidney function, and consequently predicting DGF could get a better post-transplant management. Method This is a longitudinal study of 886 renal transplant recipients from our center during the first post-transplant month. As we are searching for functional biochemical markers in renal transplant from decesased donors, we excluded patients with primary gtaft disfunction.The final simple was composed of 574 adult kidney transplant recipients, 348 renal transplant from donors after circulatory death (DCD) and 226 from donors after brain death (DBD). The following are analyzed 5creatinine concentrations, serum Lactate dehydrogenase (LDH) and urinary creatinine excretion rate (CER). Results In DCD there was a significant correlation between DGF duration and all KeGFR and CER determinations during the first post-transplant week. The parameters that achieved the best correlation to predict DGF were KeGFR (r = 0.515; p<0.001) and CER on the fourth day (r = 0.584; p<0.001) (Figure 1). In the DBD, a weak correlation was observed between DGF duration and KeGFR determinations in the first days, being KeGFR at the fourth day the one that presented the highest correlation (r = 0.59 p<0.001). We observed that serum LDH on the first day in the DBD group is associated with worse renal graft function at first, third month and one year after transplantation (p<.045, p<.05 and p<.067 respectively). Conclusion The determination of KeGFR and CER could predict the duration of DGF, especially in DCD recipients. DCD recipients with DGF have significantly better graft survival at one year than DBD recipients with DGF. (p<.001).