Humoral Response to BNT162b2 mRNA Covid19 Vaccine in Peritoneal and Hemodialysis Patients: a Comparative Study

Abstract

Introduction Generalized immunization against COVID19 has become the cornerstone in prevention of associated severe acute respiratory syndrome. Maintenance dialysis patients (MDP) are at higher risk of both exposure and mortality from the disease. Efficacy and security of BNT162b2 vaccine is well documented for the general population, but not in MDP, particularly in peritoneal dialysis (PD) patients. This study aims to compare humoral response between HD and PD patients. Materials and Methods Observational prospective study including MDP on HD or PD program from a Portuguese middle-sized Nephrology Center, who received BNT162b2. Specific anti-Spike IgG was measured as arbitrary units per milliliter (AU/mL) on two separate occasions: 3 weeks after the first dose and 3 weeks after the second. The two modality groups were compared both for absolute value and number of non-responders (NR) after both inoculations. Demographic data was also obtained and compared. Results Of 73 patients enrolled, 67 were eligible for the final study: 42 HD and 25 PD patients. PD group developed significantly higher antibody titers both after first (Med 5.44 vs 0.99; p<0.01) and second dose (Med 170.43 vs 65.81; p<0.01). HD status was associated with non-responding after the first dose (Phi=0.383; p<0.01), but not after the second one (p=0.08). Age, Charlson Comorbidity Index and dialysis vintage were lower in the PD group (p<0.01; p=0.02; p<0.01, respectively). Conclusion This study demonstrated a better humoral response to immunization with BNT162b2 in PD patients, when comparing to HD patients, after both inoculations. Both groups showed substantial humoral response after just one dose of the vaccine. Older age and higher comorbidity burden may explain the relative immunogenicity deficit, probably in a superior degree comparing with age matched healthy population.