Five-Month Impact of Tozinameran (BNT162b2) Vaccine on Kidney Transplant and Dialysis Patients: Serology and Clinical Outcomes

Background: Dialysis-treated (DT) and kidney transplant (TX) patients face higher morbidly and mortality risks than the general population during COVID-19 pandemic. Determining humoral response and associated COVID-19 morbidity after vaccination will guide risk assessment and changes in vaccination policy in this vulnerable population. Methods: Prospective cohort study up to 5 months follow-up after Tozinameran or SARS-CoV-2 infection. Primary outcomes: qualitative and quantitative anti S1/ S2 antibody (ABs) and disease rates during follow up. Anti-SARS-2 IgG ABs were quantified using LIAISON SARS-CoV-2 S1/S2 IgG (DiaSorin) immunoassay in serum of TX, DT and treating team at our hospital. Demographics and clinical data were collected from participants files. Results: 174 DT patients (40% women, age 65±15 years) 253 TX patients (33%, 53±14 years) and 71 control participants (65%, 44±14 years) were recruited. 3 months or more after vaccination we detected anti S1/S2 ABs in 81% of DT (95%CI, 72-90%), 43% of TX (95%CI, 29-57%) and 100% of controls. After COVID-19 respective rates were 94% (95%CI, 83-100%), 75% (95%CI, 60-90%) and 100%. Quantitative titers were in line with qualitative ones. Predictors of negative serology were older age, diabetes, cancer history, lower lymphocyte count and lower vitamin D. Peritoneal dialysis predicted higher titers compared to hemodialysis. In TX, hypertension and higher levels of immnosupression predicated lower titers. Vaccination was associated with fewer subsequent COVID-19 infections (HR=0.23, 95% CI 0.05-0.99, p<0.05). Higher antibody titers associated with fewer events, HR 0.41/unit increase in log10 titer (p<0.05). Conclusions: Patients with ESRD, particularly TX, mounted delayed and diminished antibody response to vaccination, and lesser response was associated with more infections. Thus, measures to protect non-responsive patients are urgently required.