Anti-Neutrophil Cytoplasmic Antibodies Vasculitis; myalgia; fever; pauciimmune vasculitis with crescentic Glomerulonephritis; acute kidney injury following Anti-Neutrophil Cytoplasmic Antibodies Vasculitis; microscopic hematuria; hyperkalemia; pauciimmune vasculitis with crescentic Glomerulonephritis; Initial information received via other healthcare professional on 08-May-2023 regarding an unsolicited valid serious case issued from a literature abstract.  This case involves a 67 years old male patient who experienced anti-neutrophil cytoplasmic antibodies vasculitis and acute kidney injury following anti-neutrophil cytoplasmic antibodies vasculitis while receiving vaccine influenza vaccine (latency: 3 weeks).  The patient's past medical treatment(s), vaccination(s) and family history were not provided. His medical history included diabetes, hypertension and congestive heart failure.   On an unknown date, the patient received a dose of suspect influenza vaccine produced by unknown manufacturer lot number not reported via unknown route in unknown administration site.  The patient presented to emergency room with complaints of fever (pyrexia) and myalgia for 3 weeks. Admission vitals and clinical examination were normal. He denied any systemic symptoms. Initial investigations revealed acute kidney injury with serum creatinine of 4.5, hyperkalemia of 6.1 (Hyperkalaemia) and elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) with microscopic hematuria (Haematuria). Autoimmune work up was significant for elevated myeloperoxidase-antineutrophil cytoplasmic antibodies (MPO-ANCA) titers. Kidney histopathology showed pauciimmune vasculitis with crescentic Glomerulonephritis (Glomerulonephritis rapidly progressive; vasculitis). He had received flu vaccine 3 weeks prior to onset of symptoms. During hospitalization he was treated with steroids, cyclophosphamide and plasmapheresis that resulted in improvement in renal function.   Action taken: Not applicable Corrective treatment: steroids, cyclophosphamide and plasmapheresis for acute kidney injury; steroids for anti-neutrophil cytoplasmic antibodies vasculitis  Outcome: Recovering for acute kidney injury and unknown for anti-neutrophil cytoplasmic antibodies vasculitis  Seriousness criteria: Medically significant and hospitalization for anti-neutrophil cytoplasmic antibodies vasculitis and acute kidney injury following anti-neutrophil cytoplasmic antibodies vasculitis  Reporter causality: Related for anti-neutrophil cytoplasmic antibodies vasculitis and acute kidney injury following anti-neutrophil cytoplasmic antibodies vasculitis; Sender's Comments: Sanofi Company Comment on 12-MAY-2023: This case involves a 67 years old male patient who experienced anti-neutrophil cytoplasmic antibodies vasculitis and acute kidney injury following anti-neutrophil cytoplasmic antibodies vasculitis while receiving vaccine influenza vaccine. Based on the limited information provided regarding this case, causal role of the company suspect product cannot be excluded. Case will be re-evaluated post further update on the patient's underlying disease conditions, past drug history, concurrent illnesses and concomitant medications.