Acute and chronic kidney injury following COVID-19 infection and vaccination: a narrative review.

This narrative review examines acute and chronic kidney injury following COVID-19 infection and vaccination, discussing the mechanism of SARS-CoV-2 entry into host cells through the ACE2 receptor - highly expressed in renal tissues - facilitating the viral invasion. Viral RNA has been detected in the urine of patients infected with SARS-CoV-2, suggesting direct renal involvement. The incidence of Acute Kidney Injuriy (AKI) among hospitalized COVID-19 patients was particularly higher in the early stages of the pandemic and largely varied by 29%-46%, depending on population studied and COVID-19 wave. Pathological findings include Acute Tubular Injury (ATI), collapsing glomerulopathy, and focal segmental glomerulosclerosis. Major risk factors for AKI comprise older age, male sex, diabetes, hypertension, cardiovascular disease, and preexisting Chronic Kidney Disease (CKD). AKI significantly increases mortality of COVID-19 patients, particularly in advanced stages of renal failure. CKD is also associated with severe COVID-19 outcomes, including increased hospitalization, intensive care admission, and mortality. Patients with CKD show a dose-dependent relationship between disease stage and adverse patient outcomes. This review further addresses renal complications following COVID-19 vaccination, which, although rare, encompass various immune-mediated glomerular diseases. Minimal Change Disease (MCD) is most frequently reported after COVID-19 vaccination, followed by IgA nephropathy, membranous nephropathy, anti-glomerular basement membrane (anti-GBM) nephritis, and ANCA-associated vasculitis. These conditions commonly present with hematuria, proteinuria, or nephrotic syndrome, and many respond to corticosteroid or immunosuppressive therapy. Other less frequent renal complications include thrombotic microangiopathy, acute tubulointerstitial nephritis, and IgG4-related nephritis. In conclusion, both COVID-19 infection and vaccination can be associated with a spectrum of renal manifestations ranging from AKI to CKD and immune-mediated glomerulopathies. Awareness, early detection, and multidisciplinary management are essential to reduce renal morbidity and improve patient outcomes.