IgA Nephropathy with Gross Hematuria Following COVID-19 mRNA Vaccination.

A 28-year-old woman experienced gross hematuria after the administration of the second dose of an messenger ribonucleic acid (mRNA) vaccine (BNT162b2). She was diagnosed with Immunogloblin A nephropathy (IgAN) by a renal biopsy two weeks after vaccination, which revealed a mild increase in mesangial cells and a matrix with co-depositions of galactose-deficient IgA1 and C3 in the mesangial region. The gross hematuria and proteinuria gradually improved without any medication, suggesting that immune activation by the mRNA vaccine may not elicit continuous disease progression of IgAN. Thus, further studies investigating the relationship between mRNA vaccines against COVID-19 and the progression of IgAN should be conducted.