Safety and Efficacy of Intramuscular Tixagevimab-Cilgavimab in Prevention of COVID-19 in Immunocompromised Patients

Background: Vaccine efficacy for COVID-19 was reported to be lower in immunocompromised patients, however they have increased risk of severe COVID-19 infection, compared to immunocompetent patients. Tixagevimab-Cilgavimab are monoclonal antibodies to help build immune defense against COVID-19, but its safety and efficacy specifically in immunocompromised patients are unknown. Our objective was to investigate safety and efficacy of Tixagevimab-Cilgavimab in immunocompromised patients.Methods: Retrospective case study of immunocompromised patients who received Tixagevimab-Cilgavimab between January 3, 2022 to July 31, 2022 in Kaiser Permanente Southern California, an integrated healthcare setting that includes 15 medical centers within Southern California. All patients were followed for 180 days after their Tixagevimab-Cilgavimab administration. Immunocompromised patients, defined as patients with solid tumor and hematologic malignancies, primary immunodeficiencies, recipients of solid organ or hematopoietic stem cell transplants, and patients who received treatment with immunosuppressive medications (such as chemotherapy, high-dose corticosteroids, tumor necrosis factor blockers, and certain biologic agents), were included in the study.Findings: 2,352 immunocompromised patients were identified in the study. 101 patients (4.3%) had incidence of COVID-19 and 13 patients (0.6%) had COVID-19 related hospital admissions, with no mortality, within 180 days of Tixagevimab-Cilgavimab. Four patients (0.17%) received same-day medical care after Tixagevimab-Cilgavimab administration. There were 39 non-COVID-19 related hospital admissions (1.7%) within 30 days and 11 hospital admissions (0.5%) within 7 days of Tixagevimab-Cilgavimab.Interpretation: Tixagevimab-Cilgavimab is effective in preventing severe COVID-19 with minimal adverse effects in immunocompromised patients.Funding: This study was non-funded.Declaration of Interest: All authors declare that they have no conflicts of interest.Ethical Approval: This study has been approved by KPSC’s Institutional Review Board.