Vaccine-Associated Proteinase 3 Anti-neutrophil Cytoplasmic Antibodies (PR3-ANCA) Vasculitis: A Case Report and Review of Emerging Evidence.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a rare autoimmune condition characterized by necrotizing inflammation of small- to medium-sized vessels. While various environmental triggers have been implicated, the role of the COVID-19 vaccine as a possible trigger is still being studied. We describe the case of a 21-year-old female patient who developed systemic inflammatory symptoms within 24 hours of receiving her second dose of the Covishield (ChAdOx1 nCoV-19) COVID-19 vaccine. Initial manifestations included acute-onset polyarthralgia with tenderness and fatigue, followed by multiple episodes of vomiting, nausea, and diffuse abdominal discomfort. The physical examination revealed a diffuse, non-blanching purpuric rash over the lower extremities. Laboratory evaluation revealed severe anemia, raised inflammatory markers, and impaired renal and hepatic function. Further tests revealed the rheumatoid (RA) factor being positive, followed by cytoplasmic ANCA (c-ANCA) proteinase 3 (PR3), strongly positive. Based on clinical and serological findings, a diagnosis of PR3-AAV was established. The patient received packed red blood cell transfusions, was initiated on high-dose corticosteroids, and was subsequently treated with rituximab. Clinical improvement was observed alongside normalization of inflammatory and renal parameters. This case highlights a potential temporal association between COVID-19 vaccination and the onset of AAV. Although a direct cause cannot be established, awareness of this possible complication is essential for the timely recognition and management of post-vaccination autoimmune phenomena.