ABSTRACT
Background: Novel messenger RNA (mRNA)-based vaccines play an important role in current vaccination campaigns against SARS-CoV-2. They are highly efficacious and generally well tolerated. Vaccination in patients with immune-mediated kidney diseases is recommended. A number of cases with de novo or relapsing glomerulonephritis shortly after vaccine application have been reported, some of which presented with gross haematuria. Methods: We collected 10 cases of macrohaematuria following mRNA-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination at our tertiary care institution and referring centres. Additionally, we pooled all 25 published cases from the literature with ours to analyse their clinical characteristics. Results: Most macrohaematuria episodes (72.2%) began within 2 days after vaccination, the majority after the second dose. In some individuals, repeated episodes occurred after subsequent doses of the same vaccine. A total of 65.7% of patients never had macrohaematuria before. A total of 45.7% were known to suffer from immunoglobulin A nephropathy (IgAN); the rest had no prior renal diagnosis. IgAN was the most frequent new diagnosis, but anti-neutrophil cytoplasmic antibody-associated vasculitis and anti-glomerular basement membrane disease were also identified. Acute kidney injury (AKI) occurred in 28.6% of patients, with an increase in serum creatinine not meeting Kidney Disease: Improving Global Outcomes AKI criteria in 28.6%. Treatment ranged from conservative management, renin-angiotensin-aldosterone system inhibitors, steroids and cyclophosphamide to plasmapheresis. While renal outcomes were mainly favourable in isolated IgAN, they were poor in patients with additional or isolated small vessel vasculitis. Conclusion: Awareness of gross haematuria after SARS-CoV-2 vaccination is important. Close follow-up and additional work up, particularly in individuals without known underlying kidney disease or worsening renal function, is essential. For patients with vaccine-associated macrohaematuria, an alternative vaccine class might be considered for subsequent vaccinations.