New Onset Biopsy-Proven Nephropathies after COVID Vaccination.

Introduction: To date, almost 7 billion doses of the different types of vaccine against SARS-CoV-2 have been administered worldwide. Although the severity of new cases of SARS-CoV-2 has progressively decreased, and the pressure on national health systems has declined, the development of de novo glomerular injuries has been suggested.

Methods: This study aimed to examine the patients who were hospitalized in our Unit between April and November 2021 and underwent renal biopsy for new-onset urinary abnormalities (UA) and/or renal impairment within 3 months of SARS-CoV-2 vaccination.

Results: We identified 17 patients who developed UA and/or renal insufficiency within 3 months of vaccination. Minimal change disease was the most common disease in our cohort (5 patients, 29.4%) followed by acute tubulointerstitial nephritis (TIN; 3 patients, 17.6%), membranous nephropathy (3 patients, 17.6%), and rapidly progressive IgA nephropathy (2 patients, 11.8%). The other 4 patients had a diagnosis of membranoproliferative glomerulonephritis (1 patient), systemic lupus erythematosus (1 patient), ANCA-associated vasculitis (1 patient), and tip-variant focal segmental glomerulosclerosis (1 patient), respectively. Eight out of the 17 patients (47.1%) developed acute kidney injury. Two patients with acute TIN had to start hemodialysis that was discontinued after 1 and 2 months, respectively, due to the recovery of renal function. All patients underwent treatment with corticosteroids and/or immunosuppressants.

Discussion: Although it is not possible to conclusively determine whether there is a causal relationship between SARS-CoV-2 vaccination and new-onset nephropathies, based on the appearance of UA and/or renal insufficiency shortly after vaccination, we hypothesize that the immune response to the COVID-19 vaccine may be a trigger of nephropathies. Therefore, our results highlight the need for pharmacovigilance. However, this report should not lead to vaccine hesitation during this pandemic as the benefits of vaccination strongly outweigh the potential risks.