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Immunocompromised patients, such as those with a haematological malignancy, are at higher risk of SARS-CoV-2 infection, severe outcomes and mortality. Tixagevimab/cilgavimab is a monoclonal antibody combination which binds to the SARS-CoV-2 spike protein. The PROVENT phase III clinical trial reported that tixagevimab/cilgavimab prophylaxis significantly reduced the risk of COVID-19 infection in immunocompromised participants. However, the trial was conducted before the Omicron variant became prevalent. This systematic review and meta-analysis provide an up-to-date summary of the real-world effectiveness of tixagevimab/cilgavimab in immunocompromised patients, including patients with haematological malignancies. Clinical studies from 1 January 2021 to 1 October 2022, which reported breakthrough COVID-19 infections after tixagevimab/cilgavimab, were included. COVID-19-related hospitalisations, intensive care admissions and mortality were also assessed. A meta-analysis was performed to ascertain overall clinical effectiveness. Eighteen studies, with 25 345 immunocompromised participants, including 5438 patients with haematological pathologies, were included in the review. The overall clinical effectiveness of tixagevimab/cilgavimab against COVID-19 breakthrough infection, hospitalisation, intensive care admission and COVID-19-specific mortality was 40.54%, 66.19%, 82.13% and 92.39%, respectively. This review highlights the clinical effectiveness of tixagevimab/cilgavimab at reducing COVID-19 infection and severe outcomes for immunosuppressed individuals, including patients with a haematological malignancy, during the Omicron-predominant era. Real-world studies are important to provide ongoing certainty of the clinical benefit for immunocompromised patients against new SARS-CoV-2 variants.

Original publication




Journal article


Br J Haematol

Publication Date



COVID-19, SARS-CoV-2, efficacy, immunocompromised, tixagevimab/cilgavimab