Abstract: medRxiv preprint doi: https://doi.org/10.1101/2021.11.30.21266756; this version posted December 1, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license . Association of subcutaneous or intravenous route of administration of casirivimab and imdevimab monoclonal antibodies with clinical outcomes in COVID-19 Authors: Erin K. McCreary PharmD1*, J. Ryan Bariola MD1, Richard J. Wadas MD2, Judith A. Shovel BSN3, Mary Kay Wisniewski MA3, Michelle Adam RN2, Debbie Albin BS4, Tami Minnier MS3, Mark Schmidhofer MD5, Russell Meyers MBA2, Oscar C. Marroquin MD6, Kevin Collins MBA6, William Garrard PhD6, Lindsay R. Berry PhD7, Scott Berry PhD7, Amy M. Crawford PhD7, Anna McGlothlin PhD7, Kelsey Linstrum MS8, Anna Nakayama MS8, Stephanie K. Montgomery MS8, Graham M. Snyder MD MS1, Donald M. Yealy MD2, Derek C. Angus MD MPH8,10, Paula L. Kip PhD8, Christopher W. Seymour MD MSc8-10, David T. Huang MD MPH2,8-10, Kevin E. Kip PhD6 1. Division of Infectious Diseases, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA 2. Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA 3. Wolff Center, UPMC, Pittsburgh, PA, USA 4. Supply Chain Management/HC Pharmacy, UPMC, Pittsburgh, PA, USA 5. Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA 6. Clinical Analytics, UPMC, Pittsburgh, PA, USA 7. Berry Consultants, Austin, TX, USA 8. Office of Healthcare Innovation, UPMC, Pittsburgh, PA, USA 9. Clinical Research Investigation and Systems Modeling of Acute Illness (CRISMA) Center, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA 10. Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA *Corresponding Author: Erin K. McCreary, PharmD, BCPS, BCIDP Clinical Assistant Professor of Medicine, University of Pittsburgh Director of Stewardship Innovation, UPMC and Infectious Disease Connect Falk Medical Building, Suite 5B 3601 Fifth Avenue Pittsburgh, PA 15213 C: 484-515-9589 E: mccrearye3@upmc.edu Funding: This work did not receive external funding. The U.S. federal government provided the monoclonal antibody treatment reported in this manuscript. Abstract word count: 347 Manuscript word count: 2,996 Tables: 4 Figures: 1 Conflict of Interest: None of the authors received any payments or influence from a third-party source for the work presented. 1 NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice. medRxiv preprint doi: https://doi.org/10.1101/2021.11.30.21266756; this version posted December 1, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license . Key Points Question: Among outpatients with mild to moderate COVID-19, is subcutaneously administered casirivimab and imdevimab associated with improved risk-adjusted 28-day clinical outcomes compared to non-treatment with monoclonal antibodies, and clinically similar association compared to intravenously administered..