Effectiveness of oseltamivir in reducing COVID-19-related in-hospital deaths: A pharmacoepidemiological study

Background: Oseltamivir is a low-cost antiviral agent that could support or complement treatment of COVID-19. This study assessed whether oseltamivir is effective in reducing COVID-19-related mortality. Methods: This retrospective cohort study evaluated real-world data from a nationwide database of hospitalisation due to severe acute respiratory syndrome in Brazil. Propensity score matching was used to mimic a randomised controlled trial with 'oseltamivir' and 'no antivirals at all' as the intervention and control groups, respectively. Results: A total of 21 480 and 268 486 patients admitted between February 2020 and January 2023 were included in the intervention and control groups, respectively. After matching, the odds ratio (OR) for death was 0.901 (95% confidence interval [CI] 0.873-0.930). The OR (95% CI) for death in patients who were admitted to the ICU, and on non-invasive or invasive ventilation was 0.868 (0.821-0.917), 0.935 (0.893-0.980), and 0.883 (0.814-0.958), respectively. Conclusions: Overall, the use of oseltamivir was associated with an attributable risk reduction of 2.50% (95% CI 1.77-3.29). Similar results were observed in patients who were admitted to the ICU, and on noninvasive or invasive ventilation. Oseltamivir is a low-cost potential antiviral treatment for COVID-19. (c) 2024 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )