Long Term Humoral Immunity Decline in Hemodialysis Patients Following SARS-CoV-2 Vaccination

Dialysis patients are extremely vulnerable to SARS-CoV-2 infection with high rates of hospitalization and mortality rates estimated at 20-30%. In January of 2021, the University of Virginia Dialysis Program initiated a program wide vaccination campaign administering Pfizer BioNTech mRNA SARS-CoV-2 (BNT162b2) vaccine. To characterize the time-dependent decline in humoral immunity, we performed a prospective cohort study measuring serial monthly semi quantitative IgG antibody levels to the SARS-CoV-2 spike protein receptor binding domain in fully vaccinated in-center hemodialysis patients. Measurements were taken beginning at 2 months post full vaccination through 6 months after full vaccination. Early results showed similar seroconversion rates as prior studies with 88% obtaining positive antibody levels. Those with prior infection obtained the highest antibody levels. Over the ensuing months, patient antibody levels declined at an adjusted average rate of 31% per month. At the conclusion of the study, 40% of patients remaining in the cohort possessed either negative or borderline IgG antibody levels. Projecting future antibody levels based on the slopes of antibody level decay suggests 65% of the cohort will progress to borderline or negative antibody levels at 10 months post full vaccination. In summary, we studied long term vaccine response following vaccination with the BNT162b2 mRNA vaccine in hemodialysis patients. Our data adds to the limited pool of data in this patient population and will help to inform the discussion about vaccine booster needs and frequency.