Effectiveness of Casirivimab-Imdevimab Monoclonal Antibody Treatment among High-Risk Patients with Severe Acute Respiratory Syndrome Coronavirus 2 B.1.617.2 (Delta Variant) Infection

Background: Real-world data on the effectiveness of neutralizing casirivimab-imdevimab monoclonal antibody (Cas-Imd mAb) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among high-risk patients may inform the response to future SARS-CoV-2 variants. Methods: This study covers an observational retrospective data analysis in Banner Health Care System sites, mainly in Arizona. During the study period, the prevalence of SARS-CoV-2 Delta variant was between 95% and 100%. Of 29 635 patients who tested positive for coronavirus disease 2019 (COVID-19) between 1 August 2021 and 30 October 2021, in the Banner Health Care System, the study cohort was split into 4213 adult patients who received Cas-Imd mAb (1200 mg) treatment compared to a PS-matched 4213 untreated patients. The primary outcomes were the incidence of all-cause hospitalization, intensive care unit (ICU) admission, and mortality within 30 days of Cas-Imd mAb administration or Delta variant infection. Results: Compared to the PS-matched untreated cohort, the Cas-Imd mAb cohort had significantly lower all-cause hospitalization (4.2% vs 17.6%; difference in percentages, -13.4 [95% confidence interval {CI}, -14.7 to -12.0]; P <. 001), ICU admission (0.3% vs 2.8%; difference, -2.4 [95% CI, -3.0 to -1.9]; P <. 001), and mortality (0.2% vs 2.0%; difference, -1.8 [95% CI, -2.3 to -1.3]; P <. 001) within 30 days. The Cas-Imd mAb treatment was associated with lower rate of hospitalization (hazard ratio [HR], 0.22 [95% CI,. 19-.26]; P <. 001) and mortality (HR, 0.11 [95% CI,. 06-.21]; P <. 001). Conclusions: Cas-Imd mAb treatment was associated with a lower hospitalization rate, ICU admission, and mortality within 30 days among patients infected with the SARS-CoV-2 Delta variant. © 2022 The Author(s). Published by Oxford University Press on behalf of Infectious Diseases Society of America.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]