Adverse reactions and effects on renal function of COVID-19 vaccines in patients with IgA nephropathy.

Background: Although vaccination has been reported to reduce the morbidity and severity of COVID-19 infection in patients with kidney disease, gross hematuria is frequently reported following vaccination in patients with IgA nephropathy. We investigated the frequency of gross hematuria following COVID-19 vaccination and its effect on renal function in IgA nephropathy patients.

Methods: Adverse reactions after two or more COVID-19 vaccine doses were investigated in 295 IgA nephropathy patients attending Osaka Cty general hospital from September 2021 to November 2022. We compared differences in background characteristics and other adverse reactions between groups with and without gross hematuria after vaccination, and examined changes in renal function and proteinuria.

Results: Twenty-eight patients (9.5%) had gross hematuria. The median age of patients with and without gross hematuria was 44 (29-48) and 49 (42-61) years, respectively, indicating a significant difference. The percentage of patients with microscopic hematuria before vaccination differed significantly between those with (65.2%) and without (32%) gross hematuria. Adverse reactions, such as fever, chills, headache and arthralgia, were more frequent in patients with gross hematuria. There was no difference in renal functional decline after approximately 1 year between patients with and without gross hematuria. We also found no significant changes in estimated glomerular filtration rate or proteinuria before and after vaccination in the gross hematuria group. However, some patients clearly had worsening of renal function.

Conclusions: While COVID-19 vaccination is beneficial, care is required since it might adversely affect renal function in some patients.