MO911: Prevalence of SARS-COV-2 Cellular and Humoral Immunity in Dialysis Patients After 8 Months of Vaccination Campaign in Portugal

Abstract

BACKGROUND AND AIMSImmunization of dialysis dependent patients remains the single most important protective approach in prevention of serious COVID-19 infection. This study aims to characterize the prevalence of humoral and cellular immunity in maintenance dialysis patients (MDP) in a Nephrology Centre, 8 months after vaccination onset.METHODA single-center cross-sectional study enrolling patients on peritoneal (PD) and haemodialysis (HD) from a public-funded Portuguese Nephrology Centre. This study evaluated both humoral and cellular immunity to the COVID-19 vaccination. Humoral response was measured as specific IgG (S-RBD IgG), and cellular response as T-cell reactivity through IFN- γ quantification as response to antigen (IGRA). Further demographic and clinical variables were obtained to assess the risk factors of low immunity.RESULTSOf the 86 patients enrolled, 79.4% and 84.1% showed humoral and cellular immunity, respectively. Quantitatively, IgG S-RBD titers correlated with specific T-cell reactivity (ρ = 0.58, P < 0.001). Vaccination before dialysis initiation was associated with an absent cellular response (P = .006). Subgroup analysis associated high comorbidity burden (quantified through the Charlson comorbidity index) and low serum albumin levels as predictors of immunity (P < 0.05, variable). PD patients showed lower cellular response (297.1 mUI/mL versus 695.4 mUI/mL, P = 0.03) at 8 months following BNT162b2.CONCLUSIONThe prevalence of humoral and cellular immunity against SARS-CoV-2 in vaccinated Portuguese MDP is high. Vaccination in imminent pre-dialysis patients, high comorbidity burden and low serum albumin are some of the identified risk factors for absent immunity. PD-associated effector memory T-cell changes are suggested as contributing to the difference verified in cellular response.Table 1.Descriptive group and subgroup analysisComplete samplen = 88Subgroup An = 79Subgroup Bn = 68Age (years), mean (σ)69.9 (12.7)70.4 (12.5)70.2 (13.2)Sex (female/male), n (%)30 (34.1)29 (36.7)23 (33.8)Modality (HD/PD), n (%)67 (76.1)21 (23.9)60 (75.9)19 (24.1)49 (72.1)19 (27.9)Dialysis vintage at vaccination, months, mean (σ)-a-a29.7 (26.7)Diabetes, n (%)38 (43.2)35 (44.3)31 (45.6)Charlson comorbidity index, mean (σ)6.8 (2.5)6.8 (2.5)6.8 (2.5)Nephrosclerosis, n (%)24 (27.3)22 (27.8)18 (26.5)Immune disorders, n (%)7 (8)5 (6.3)2 (2.9)CKD stage at vaccination Maintenance dialysis, n (%) Stage 5 CKD, n (%) 79 (89.8)9 (10.2) 74 (14.8)5 (6.3) 68 (100)0Time from vaccination to immune status evaluation-8 monthsVaccineBNT162b2, n (%)ChAdOx1 nCov-19, n (%)Ad26.COV2.S, n (%)None, n (%) 78622 72520 68000Contact with SARS-CoV-2COVID-19 infection, n (%)Asymptomatic, n (%) 34 00 00Humoral responseIgG-RBD (AU/mL), median (IQR)NR, n (%) 4.6 (14)19 (21.6) 4.7 (12.8)16 (20.3) 4.6 (11.4)14 (20.6)Cellular responseIGRA (mUI/mL), median (IQR)NR, n (%) 574.8 (1376.9)14 (15.9) 571.8 (940.6)11 (13.9) 530 (914.9)10 (14.6)Laboratory variablesALB, mean (σ)iPTH, mean (σ)CRP, mean (σ) 3.5 (0.5)301.1 (317.7)1.1 (1.5) 3.6 (0.4)310.7 (318.2)1 (1.5) 3.6 (0.4)328.6 (331.5)1 (1.6)σ: standard deviation; CKD: chronic kidney disease; IQR: interquartile range; IGRA: interferon-γ release assay; NR: non-responsive; sALB: serum albumin; iPTH: intact parathormone; CRP: C-reactive protein. aBoth groups included patients who were not on dialysis.