Abstract
BACKGROUND AND AIMS
Immunization 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.
METHOD
A 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.
RESULTS
Of 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.
CONCLUSION
The 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 analysis
| Complete samplen = 88 | Subgroup An = 79 | Subgroup Bn = 68 | |
|---|---|---|---|
| Age (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 | -a | 29.7 (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) 0 |
| Time from vaccination to immune status evaluation | - | 8 months | |
| Vaccine BNT162b2, n (%) ChAdOx1 nCov-19, n (%) Ad26.COV2.S, n (%) None, n (%) |
78 6 2 2 |
72 5 2 0 |
68 0 0 0 |
| Contact with SARS-CoV-2 COVID-19 infection, n (%) Asymptomatic, n (%) |
3 4 |
0 0 |
0 0 |
| Humoral response IgG-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 response IGRA (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 variable sALB, 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.