ABSTRACT
Background: The COVID-19 pandemic has placed substantial strain on hospital resources and has been responsible for more than 733 000 deaths in the United States. The US Food and Drug Administration has granted emergency use authorization (EUA) for monoclonal antibody (mAb) therapy for patients with early-stage high-risk COVID-19. Methods: In this retrospective cohort study, we studied the emergency department (ED) during a massive COVID-19 surge in Orange County, California, from December 4, 2020, to January 29, 2021, as a potential setting for efficient mAb delivery by evaluating the impact of bamlanivimab use in high-risk COVID-19 patients. All patients included in this study had positive results on nucleic acid amplification detection from nasopharyngeal or throat swabs, presented with 1 or more mild or moderate symptoms, and met EUA criteria for mAb treatment. The primary outcome analyzed among this cohort of ED patients was overall improvement, which included subsequent ED/hospital visits, inpatient hospitalization, and death related to COVID-19. Results: We identified 1278 ED patients with COVID-19 not treated with bamlanivimab and 73 patients with COVID-19 treated with bamlanivimab during the treatment period. Of these patients, 239 control patients and 63 treatment patients met EUA criteria. Overall, 7.9% (5/63) of patients receiving bamlanivimab had a subsequent ED/hospital visit, hospitalization, or death compared with 19.2% (46/239) in the control group (P= .03). Conclusion: Targeting ED patients for mAb treatment may be an effective strategy to prevent progression to severe COVID-19 illness and substantially reduce the composite end point of repeat ED visits, hospitalizations, and deaths, especially for individuals of underserved populations who may not have access to ambulatory care.