Anti-S, antibody against the spike protein of SARS-CoV-2; RR: relative risk; CI, confidence interval; ESRD, end-stage renal disease; AVF, arterio-venous fistula; AVG, arterio-venous graft; HD, hemodialysis; PD, peritoneal dialysis; HIV, human immunodeficiency virus; ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin II receptor blocker; nPCR: normalized protein catabolic rate. Here, ACE is linked to stage 5 chronic kidney disease.