OBJECTIVES: Tixagevimab 150 mg and cilgavimab 150 mg (T + C), a combined monoclonal antibody, help immunocompromised patients reduce the risk of infection COVID-19 through passive immunization. However, the relevant real-world studies on the use of T + C in those patients are still lacking.

METHODS: This was a retrospectively observational, single-center, three-month follow-up study conducted at a medical center (about 3,300 beds) in Taiwan. We included immunocompromised patients with solid organ transplant, blood or bone marrow transplant, CAR-T therapy, or B cell depletion therapy before one year of T + C initiation. Those patients receiving 300 mg of T + C intramuscularly as pre-exposure prophylaxis COVID-19 between October 1, 2022 and January 31, 2023 were included. Those patients were followed up three-month, COVID-19 infection and death, which came first. We used description analyses to explore potential risk factors of those who had COVID-19 after T+C as prophylaxis.

RESULTS: A total of 92 patients (64% male; median age of 60 years) were included in the study. 36 patients had received solid organ transplantation (39%), and 56 patients had B-cell depletion therapy (61%). During the three-month follow-up, 12 patients were infected with COVID-19 and 1 patient died. The incidence of COVID-19 infection was relatively higher in the elderly population (16.1% vs. 13.1%), chronic disease patients (18.3% vs. 9.3%), and cardiovascular disease patients (15.4% vs. 0%). We also found that those vaccinated patients were less likely to have COVID-19 infection than unvaccinated patients (3.8% vs. 44.4%). Moreover, comparing with different vaccines' mechanisms, there was no infection in the group with adenovirus vector vaccine, while one case was administered with the mRNA vaccines.

CONCLUSIONS: For immunocompromised patients with high risk factors (elderly, cardiovascular diseases, chronic diseases), they should still be aware of the risk of infection even with given T + C as a prophylaxis for COVID-19.