Background and Importance In the context of pre-exposure prophylaxis of COVID-19 in adults and adolescents aged 12 years and older (> 40 kg), tixagevimab-cilgavimab is currently included in clinical guidelines. The recommended dose is administered as two separate sequential intramuscular injections (150 mg of tixagevimab and 150 mg of cilgavimab), preferably in the gluteal muscles. Due to their recent authorisation, effectiveness and security of this treatment is not well known.
Aim and Objectives The aim of this study was to analyse the effectiveness and security of tixagevimab-cilgavimab in patients with COVID-19 risk after a complete vaccination regimen, collated with the data from PROVENT clinical trial.
Material and Methods Retrospective observational study in a cohort of COVID-19 risk patients. Electronic medical record and prescription application were used to collect the following data: sex, age, comorbidities, anticoagulation, and titles of anti-Spike antibodies, and COVID-19 infections after administration.
Results The study includes 41 patients (52.5% women, median age 64.5 years (SD 13.5)), who were candidates to prophylaxis because of their comorbidities: anti-CD20 active treatment (21), solid organ transplantation (renal (10) and pulmonary (14)), chronic kidney disease (2), immunosuppression (1), cytotoxic chemotherapy (1) or haematopoietic Stem Cell transplant (1). After the last vaccination, 97.5% of the patients had low antibodies (< 260 BAU/mL), which demonstrates an inadequate response to active immunisation. These comorbidities and clinical conditions were similar in PROVENT.
In PROVENT, the duration of protection is estimated to be at least 6 months (0.2% COVID-19 positive cases after administration prior to day 183). In our study population, 3 patients were COVID-19 positive (7.5%) prior to day 90 after administration without severe or critical symptomatic illness.
As with any other intramuscular injections, should be given with caution to patients with thrombocytopenia or coagulation disorders; 5 patients were on anticoagulation therapy and no bleeding events were recorded. Therefore, non-hypersensitivity reactions have been observed.
Conclusion and Relevance Effectiveness and security of the pre-exposure prophylaxis with tixagevimab-cilgavimab was adequate in most of the patients treated, and similar to the data of the clinical trials. Even so, pre-exposure prophylaxis is not a substitute for vaccination. Nevertheless, further studies were necessary to establish the effective and security profile.
Conflict of Interest No conflict of interest
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