Tixagevimab-Cilgavimab Decreases the Rate of SARS-CoV-2 Infection Among Solid Organ Transplant Recipients

Background. SARS-CoV-2 infection in solid organ transplant (SOT) recipients is associated with high morbidity and mortality. Tixagevimab/cilgavimab monoclonal antibodies were previ-ously authorized for pre-exposure prophylaxis for immunocompromised individuals. We aimed to determine if tixagevimab/cilgavimab could prevent breakthrough SARS-CoV-2 infection in SOT recipients.Material and Methods. We conducted a prospective single-center study of SOT recipients who received tixagevimab/cilgavimab compared with those who did not. Demographics, type of transplant, immunosuppression regimen, COVID-19 vaccination status, and tixagevimab/cilgavi-mab administration data were collected. Participants were interviewed for 6 months or until they tested positive for SARS-CoV-2, whichever came first. Kaplan-Meier SARS-CoV-2-free survival curves were created based on the tixagevimab/cilgavimab administration date and SARS-CoV-2 infection. The log-rank test was used for comparison. Univariate and multivariate Cox regression models were constructed. Results. The study cohort included 323 patients. Two hundred forty-eight received tixagevi-mab/cilgavimab, and 75 did not (control). COVID-19 vaccination rate was higher among tixage-vimab/cilgavimab recipients than nontixagevimab/cilgavimab recipients (99.6% vs 92.0%; P < .001). Twenty-six patients in the tixagevimab/cilgavimab group (10.5%) and 23 in the con-trol group (30.7%) tested positive for SARS-CoV-2 infection (P < .001). In a multivariate analy-sis, receipt of tixagevimab/cilgavimab and duration from transplant were both associated with reduced risk of SARS-CoV-2 infection (hazard ratio 0.431; 95% CI 0.224-0.828 and hazard ratio 0.917; 95% CI 0.861-0.978, respectively).Conclusion. During the study period, SOT recipients who received tixagevimab/cilgavimab had a significantly lower rate of SARS-CoV-2 infection. There were no differences in symptom frequency, illness severity, hospitalization rate, or treatment of SARS-CoV-2 infection.