Abstract: ORIGINAL ARTICLE Bamlanivimab for the Prevention of Hospitalizations and Emergency Department Visits in SARS-CoV-2–Positive Patients in a Regional Health Care System David H. Priest, MD, MPH,* Lisa M. Blanchette, PharmD, MHA,† Aliza L. Hekman, MMS, PA-C,* Rahul Maddikunta, MS,* and Paula E. Burleson, BSBA* Introduction: Bamlanivimab (LY-CoV555) was approved by Emergency Use Authorization by the United States Food and Drug Administration in the ambulatory setting to prevent hospitalizations and emergency department visits. We report a retrospective, case-control study of bamlanivimab use in a regional health care system. Methods: A retrospective case-control study for SARS-CoV-2–positive patients receiving bamlanivimab and matched controls between October 2020 and March 2021 was performed. End points included all-cause hospitalization, emergency department visits, and mortality. Results: No statistically significant difference was noted in all-cause hospitalization, emergency department visits, or mortality, including patients 65 years or older, body mass index of 35 or higher, diagnosis of diabetes mellitus, or cancer (high-risk patients). No difference was seen based on timing of bamlanivimab infusion relative to symptom onset or timing of infusion within the study period. Conclusions: Based on the evaluated endpoints, there was no benefit from bamlanivimab, regardless of when it was received in a patient's clinical course or when during the study period it was received. A lack of efficacy of monoclonal antibodies in patients infected with COVID-19 variants has been noted, but the impact of local variants on these results could not be assessed given a lack of available variant diagnostic tools. These findings do not support bamlanivimab for the prevention of hospitalization or emergency department visits for patients with mild to moderate SARS-CoV2 infection. Key Words: SARS-CoV-2, COVID-19, bamlanivimab, monoclonal antibody (Infect Dis Clin Pract 2022;30: e1130) T he COVID-19 pandemic caused by SARS-CoV-2 has had a devastating impact on the health of communities around the world, as well as the global economy.1,2 In response, several therapeutic interventions have been developed and evaluated, including virus neutralizing monoclonal antibodies.3,4 These antibodies are isolated from the blood of recovered patients after infection with SARS-CoV-2 and offer passive immunity to those receiving the antibody therapies. One such agent is bamlanivimab (LYCoV555; Lilly), a recombinant, neutralizing monoclonal antibody developed by the US Vaccine Research Center at the National Institute of Allergy and Infectious Diseases and AbCellera From the *Novant Health Institute of Safety and Quality; †Novant Health Department of Pharmacy, Winston-Salem, NC. Correspondence to: David H. Priest, MD, MPH, Novant Health Institute of Safety and Quality, Suite 600, 101 North Cherry St, Winston-Salem, NC 27101. E‐mail: dhpriest@novanthealth.org. The authors have no funding or conflicts of interest to disclose. Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the..