Effectiveness of REGEN-COV Antibody Combination in Preventing Severe COVID-19 Outcomes – A Retrospective Cohort Study ​

Background: REGEN-COV has been approved as a treatment for high-risk patients infected with SARS-CoV-2 within 5 days of their diagnosis. We aim to determine the real-world effectiveness of REGEN-COV treatment against COVID-19-related hospitalization, severe illness and death.Methods: A cohort study was performed using the data repositories of Israel’s largest healthcare organization. Patients diagnosed with COVID-19 between September 19, 2021 and December 8, 2021 who were treated with REGEN-COV were matched to patients diagnosed with COVID-19 between July 1, 2021 and December 8, 2021 who were not treated with REGEN-COV. Patients were followed until the occurrence of the outcome (i.e. severe COVID-19 illness, hospitalization, and death due to COVID-19) or until 28-days from the index date. Analysis was performed using Cox regression, with estimated treatment effectiveness defined as one minus the hazard ratio.Findings: 289 patients treated with REGEN-COV were matched with 1,294 untreated patients. The estimated effectiveness of REGEN-COV in the first 28- days after treatment was 55.2% (95% CI: 21.5-74.5%) in preventing COVID-19-related hospitalization, 59.4% (95% CI: 20.2-79.4%) in preventing severe COVID-19 illness, and 93.8% (95% CI: 54.4-99.2%) in preventing COVID-19-related death. A secondary analysis indicated that REGEN-COV was more effective in preventing COVID-19-related hospitalization among individuals younger than 60 compared to individuals aged 60 years or older.Interpretation: REGEN-COV was effective in reducing the risk of deterioration in high-risk COVID-19 patients. With many individuals remaining unvaccinated, and breakthrough infections occurring among the vaccinated, effective treatment for COVID-19 remains vital.Funding Information: None. Declaration of Interests: The authors has no conflict of interest to declare.Ethics Approval Statement: This study was approved by the CHS Institutional Review Board.