Abstract: (2021) 14:440 Holm et al. BMC Research Notes https://doi.org/10.1186/s13104-021-05847-7 BMC Research Notes Open Access RESEARCH NOTE Convalescence plasma treatment of COVID‑19: results from a prematurely terminated randomized controlled open‑label study in Southern Sweden Karin Holm1*† , Maria N. Lundgren2†, Jens Kjeldsen‑Kragh2, Oskar Ljungquist3, Blenda Böttiger4, Christian Wikén1, Jonas Öberg1, Nils Fernström1, Ebba Rosendal5, Anna K. Överby5, Julia Wigren Byström5, Mattias Forsell5, Mona Landin‑Olsson6† and Magnus Rasmussen1† Abstract Objective: Convalescent plasma has been tried as therapy for various viral infections. Early observational studies of convalescent plasma treatment for hospitalized COVID-19 patients were promising, but randomized controlled studies were lacking at the time. The objective of this study was to investigate if convalescent plasma is beneficial to hospitalized patients with COVID-19. Results: Hospitalized patients with confirmed COVID-19 and an oxygen saturation below 94% were randomized 1:1 to receive convalescent plasma in addition to standard of care or standard of care only. The primary outcome was number of days of oxygen treatment to keep saturation above 93% within 28 days from inclusion. The study was prematurely terminated when thirty-one of 100 intended patients had been included. The median time of oxygen treatment among survivors was 11 days (IQR 6–15) for the convalescent plasma group and 7 days (IQR 5–9) for the standard of care group (p = 0.4, median difference -4). Two patients in the convalescent plasma group and three patients in the standard of care group died (p = 0.64, OR 0.49, 95% CI 0.08–2.79). Thus no significant differences were observed between the groups. Trial registration ClinicalTrials NCT04600440, retrospectively registered Oct 23, 2020. Keywords: SARS-CoV2, COVID-19, Convalescent plasma, Oxygen therapy, Desaturation