Azvudine and nirmatrelvir-ritonavir in hospitalized patients with moderate-to-severe COVID-19: Emulation of a randomized target trial.

To examine the effectiveness of azvudine and nirmatrelvir-ritonavir in treating hospitalized patients with moderate-to-severe COVID-19. We emulated a target trial with a multicenter retrospective cohort of hospitalized adults with moderate-to-severe COVID-19 without contraindications for azvudine or nirmatrelvir-ritonavir between December 01, 2022 and January 19, 2023 (during the Omicron BA.5.2 variant wave). Exposures included treatment with azvudine or nirmatrelvir-ritonavir for 5 days versus no antiviral treatment during hospitalization. Primary composite outcome (all-cause death and initiation of invasive mechanical ventilation), and their separate events were evaluated. Of the 1154 patients, 27.2% were severe cases. In the intent-to-treat analyses, azvudine reduced all-cause death (Hazard ratio [HR]: 0.31; 95% CI: 0.12-0.78), and its composite with invasive mechanical ventilation (HR: 0.47; 95% CI: 0.24-0.92). Nirmatrelvir-ritonavir reduced invasive mechanical ventilation (HR: 0.42; 95% CI: 0.17-1.05), and its composite with all-cause death (HR: 0.38; 95% CI: 0.18-0.81). The study did not identify credible subgroup effects. The per-protocol analyses and all sensitivity analyses confirmed the robustness of the findings. Both azvudine and nirmatrelvir-ritonavir improved the prognosis of hospitalized adults with moderate-to-severe COVID-19.