Safety of intramuscular tixagevimab-cilgavimab (Evusheld®) administration in patients at risk of iatrogenic haematoma due to haematological disorders

Introduction: Traditionally, intramuscular (IM) injections have been avoided in patients with haematological diseases due to the risk of iatrogenic haematoma. Tixagevimab-cilgavimab (Evusheld^®) is a novel monoclonal antibody combination used as preexposure prophylaxis against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), for those at highest risk of severe infections. It is delivered as two separate IM injections (1.5 mL each). Patients with haematological disease are at higher risk for severe SARS-CoV-2 infections, which may be partially abrogated by the prophylactic inoculation of tixagevimab-cilgavimab. Methods: A combined retrospective and prospective study of patients under the haematology service at a large metropolitan hospital receiving tixagevimab-cilgavimab was conducted. Tixagevimab-cilgavimab was administered IM to all patients, with platelet and factor replacement provided according to local protocols. Patients completed a numerical pain score daily for seven days following the injection, with scores ≥4/10 prompting an ultrasound to identify iatrogenic gluteal haematomas. Results: The study recruited 131 patients; 66 patients were thrombocytopenic, including 10 patients with a platelet count <30 × 10⁹/L. Fourteen patients (10.7%) received a single platelet transfusion prior to tixagevimab-cilgavimab administration, while two patients received fresh frozen plasma. No gluteal haematomas were identified, and only two patients reported an initial pain score of ≥4/10. Conclusions: The intramuscular administration of tixagevimab-cilgavimab in patients with haematological diseases was well tolerated and was not associated with iatrogenic haematoma.