Prophylaxis with tixagevimab/cilgavimab is associated with lower COVID-19 incidence and severity in patients with autoimmune diseases

Objective: To describe the clinical efficacy of tixagevimab/cilgavimab in pre-exposure prophylaxis in patients at risk of severe coronavirus disease 2019 (COVID-19) and unresponsive to vaccination (anti-severe acute respiratory syndrome coronavirus 2 antibodies <260 binding antibody units/ml) in rheumatology.Methods: In this multicentre observational study we included patients with autoimmune or inflammatory diseases who received pre-exposure prophylaxis with tixagevimab/cilgavimab between December 2021 and August 2022. The endpoint was incidence of COVID-19 and its severity.Results: Tixagevimab/cilgavimab was administered to 115 patients with a median age of 62 years [interquartile range (IQR) 52-71], chronic arthritis (n = 53), connective tissue disease (n = 38) or vasculitis (n = 11). The main background immunosuppressants were rituximab (n = 98), corticosteroids [n = 62; median dose 5 mg (95% CI 5-8)] and methotrexate (n = 48). During a median follow-up of 128 days (IQR 93-173), COVID-19 occurred in 23/115 patients (20%) and the omicron variant was identified for the eight genotyped patients. During the study period, the average weekly incidence was 1071/100 000 inhabitants in ile-de-France vs 588/100 000 in our patients. Patients who received a two-injection regimen had a lower risk of infection than those with a single injection [16/49 (33%) vs 5/64 (8%), P = 0.0012]. The COVID-19-positive patients did not differ from uninfected patients concerning age, comorbidities, underlying rheumatic disease and immunosuppressants. All COVID-19 cases were non-severe. The tolerance of injections was excellent.Conclusion: In a population with autoimmune or inflammatory diseases at risk of severe COVID-19 unresponsive to vaccination, pre-exposure prophylaxis withy tixagevimab/cilgavimab was associated with a lower incidence of COVID-19 and no severe infections.