Effectiveness of Oral Nirmatrelvir/Ritonavir vs. Intravenous Three-Day Remdesivir in Preventing Progression to Severe COVID-19: A Single-Center, Prospective, Comparative, Real-Life Study

Background: Nirmatrelvir/ritonavir (NMV/r) and three-day course remdesivir (3RDV) have been approved as early treatments for COVID-19 outpatients not requiring supplemental oxygen. Real-life data on the efficacy of antivirals among immunocompromised patients or directly comparing their effectiveness in preventing hospitalization and/or death are scarce. Methods: Prospective, observational study conducted in a tertiary care hospital, from 1 January 2022 until 15 March 2023, during the prevalence of the Omicron variant. Inverse probability of treatment weighting (IPTW) was used to account for differences between treatment groups. Results: We included 521, mainly immunocompromised (56%), patients in our analysis; 356 (68.3%) received 3RDV and 165 (31.7%) NMV/r. Overall, 15/521 (2.9%) patients met the primary end-point of hospitalization at 30 days (3RDV arm: 10/356, 2.8% vs. NMV/r arm: 5/165, 3%, p = 1). On IPTW-adjusted univariable analysis, the choice of treatment did not affect outcomes. In multivariable logistic regression analysis, we found that one (OR 0.26, 95%CI 0.07-0.99, p = 0.049) or two (OR 0.06, 95%CI 0.01-0.55, p = 0.014) vaccine booster shots reduced the risk for adverse outcomes. Conclusion: In our patient population of high-risk, mainly immunocompromised, vaccinated patients during the prevalence of the Omicron variant, NMV/r and 3RDV were equally effective early treatments for the prevention of hospitalization and/or death.