Abstract: Mediterranean Journal of Hematology and Infectious Diseases Original Article Early Treatment with Bamlanivimab Alone does not Prevent COVID-19 Hospitalization and Its Post-Acute Sequelae. A Real Experience in Umbria, Italy. Elisabetta Schiaroli1, Giuseppe Vittorio De Socio1, Laura Martinelli2, Lisa Malincarne1, Martina Savoia3, Anna Laura Spinelli4 and Daniela Francisci1. 1 Unit of Infectious Diseases, Department of Medicine and Surgery, University of Perugia, Perugia, Italy. Internal Medicine of Città di Castello Hospital, USL Umbria 1, Italy. 3 Hospital Pharmacy of Foligno Hospital, USL Umbria 2, Italy. 4 Internal Medicine of Spoleto Hospital, USL Umbria 2, Italy. 2 Competing interests: The authors declare no conflict of Interest. Abstract. Background and Objective: The use of monoclonal antibodies to the SARS-Cov-2 spike protein for early treatment of COVID-19 disease is being evaluated, with only phase 2 studies available to date. The emergency authorization of bamlanivimab monotherapy was obtained in November 2020 by the FDA and in March 2021 by Italian agency AIFA. Its use was then revoked in April 2021 by both. This study reports the results of bamlanivimab utilization in monotherapy in Umbria (Italian region) to verify whether, in a population with multiple risk factors, comparable results to the phase 2 BLAZE1 trial had been obtained. Methods: Between March and April 2021, a retrospective observational study was performed on patients treated with bamlanivimab. Demographic and clinical characteristics before and after infusion were evaluated. Moreover, a telephone interview was conducted about 30 days after the infusion to evaluate the overall course. Results: All patients had an early infection (mean 4±1.73 days), almost all by alpha variant (97%). No adverse events to treatment were observed. Altogether within 30 days, the hospitalization rate was 20%, 15% for COVID-19 related pathologies, versus 4% at 11 days in the BLAZE1 phase 2 study. In addition, worsening of some symptoms observed at baseline such as asthenia (77 vs. 51.3%), shortness of breath (38 vs. 23%) was registered, as well as the onset of non-restorative sleep (41%). Conclusion: The clinical outcome after bamlanivimab monotherapy was far below the expectation despite the patients had been infected by a theoretically sensitive viral variant. Keywords: Bamlanivimab; COVID-19 hospitalization; real experience; Umbria. Citation: Schiaroli E., De Socio G.V., Martinelli L., Malincarne L., Savoia M., Spinelli A.L., Francisci D. Early treatment with Bamlanivimab Alone does not prevent COVID-19 hospitalization and its post-acute sequelae. a real experience in Umbria, Italy. Mediterr J Hematol Infect Dis 2021, 13(1): e2021061, DOI: http://dx.doi.org/10.4084/MJHID.2021.061 Published: November 1, 2021 Received: July 1, 2021 Accepted: October 10, 2021 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by-nc/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Correspondence to: Elisabetta Schiaroli, MD. Unit of Infectious Diseases, Department of Medicine, University of Perugia, Perugia, Italy. Hospital "Santa Maria della Misericordia", Piazzale Menghini, 1 – 06156, Perugia, Italy. Tel: +39-075-5784375 Fax: +39-075-5784346. E-mail: elisabetta.schiaroli@unipg.it Introduction. Bamlanivimab binds to SARS..