Introduction: Maintenance hemodialysis (HD) patients are at higher risk of both infection and mortality associated with the new SARS-CoV-2. Immunization through large-scale vaccination is the cornerstone of infection prevention in this population. This study aims to identify risk factors for low response to the BNT-162b2 (Pfizer BioNTech) vaccine in an HD cohort.
Materials and methods: Observational prospective study of an HD group followed in a Portuguese Public Founded Hemodialysis Center who received BNT-162b2 vaccination. Specific anti-Spike IgG was evaluated as arbitrary units per milliliter (AU/mL) and compared against risk factors.
Results: Humoral response evaluated by IgG anti-Spike levels showed a strong correlation with Charlson comorbidity index (CCI) and intact parathormone (iPTH) after each inoculation (1st dose: rho = -0.64/0.54; 2nd dose: rho = -0.66/0.63, respectively; p < 0.01 throughout). After completing both doses: 1) no response (NR) was associated with female sex (p < 0.01), lower albumin and iPTH (p = 0.01); 2) weak response (WR) showed higher CCI, older age, lower iPTH, and lower albumin (p = < 0.01, p = 0.03, p < 0.01, p = 0.05, respectively). A binary regression model using CCI, sex (male), and central venous catheter (CVC) was statistically significant in prediction of WR after the 2nd dose with OR (95% CI): 1.81 (1.06 - 3.08); 0.05 (0.01 - 0.65); 13.55 (1.06 - 174.18), respectively (p = 0.01).
Conclusion: Older age, higher CCI, lower iPTH and albumin as well as CVC as vascular access were associated with lower response to vaccination in our study. Comorbidity burden is suggested as a preferred indirect method to predict worst response when compared to age alone.