IgA vasculitis following COVID-19 vaccination.

Immunoglobulin A (IgA) vasculitis is generally triggered by infectious causes, but it has also been reported after immunisation with various vaccines. Herein, we report two cases of IgA vasculitis after receiving the first or second dose of the Pfizer-BioNTech BNT16B2b2 mRNA vaccine. Two men, aged 22 and 30 years, developed palpable purpura on the extremities and arthritis. One patient also complained of fever and gastrointestinal symptoms. Laboratory findings revealed mild leucocytosis and slightly elevated C-reactive protein levels, although the platelet count and coagulation profile were within normal levels in both cases. Proteinuria and microhaematuria were seen in one patient. Skin biopsies were performed in both patients and revealed leucocytoclastic vasculitis. The deposits of IgA and C3 were shown in immunofluorescence studies in one patient. Both patients were diagnosed with IgA vasculitis and treated with prednisolone, and their symptoms resolved within 1 week after initiation of treatment. The coronavirus disease 2019 mRNA vaccine could trigger IgA vasculitis; however, a coincidence cannot be ruled out.