Data collection and definitions
CHRONIC KIDNEY DISEASE
Co-primary outcomes of this study were the humoral and cellular immune responses at four weeks after the second vaccination. At this timepoint, SARS-CoV-2-specific anti-Receptor Binding Domain (RBD) immunoglobulin G (IgG) levels, expressed in international Binding Antibody Units (BAU)/mL, were measured in venous blood. Furthermore, capillary blood was collected with a self-collection finger prick set prior to the first and the second vaccination and four weeks after the third vaccination for additional SARS-CoV-2-specific anti-RBD IgG titer measurements. To assess cellular immunogenicity, peripheral blood mononuclear cells (PBMCs) were isolated from the blood sample that was taken four weeks after the second vaccination.Baseline characteristics were registered and measurements were performed before treatment with FCM or placebo. Body Mass Index (BMI) was calculated as weight in kilograms divided by height in meters squared. Plasma creatinine was measured in venous blood with an enzymatic photometry assay (Roche Diagnostics, Mannheim, Germany). The estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD‐EPI) equation, omitting the black race coefficient (