PRELIMINARY ANALYSIS ON EFFICACY OF RITONAVIR-BOOSTED NIRMATRELVIR ON DISEASE PROGRESSION AMONG HIGH-RISK HOSPITALISED COVID-19 PATIENTS: A RETROSPECTIVE CASE-CONTROL STUDY

INTRO: Ritonavir-boosted nirmatrelvir has shown efficacy in reducing the rate of hospitalisation and 28-day mortality among unvaccinated populations with COVID-19. The role of Ritonavir-boosted nirmatrelvir among high risk hospitalised COVID-19 patients remained uncertain. Our study aimed to assess the efficacy of Ritonavir-boosted nirmatrelvir in reducing disease progression among high-risk hospitalised COVID-19 patients. METHODS: This is a retrospective case-control study (ratio 1:1) among hospitalised COVID-19 patients with mild-moderate severity, within 5 days of illness, and had at least one risk factor for severe disease. Treatment group (case) received Nirmatrelvir and Ritonavir twice daily for 5 days. Historical controls before the introduction of Ritonavir-boosted nirmatrelvir were obtained in the same hospital. Both groups received standard of care. The primary outcome was rate of clinical progression from non-hypoxia to hypoxia. FINDINGS: 200 patients from January to July 2022 were included in the analysis, where 108 (54%) were male, mean age of 63.7 (SD 17.1), 95% completed primary COVID-19 vaccination and 91 (45.5%) had evidence of pneumonia (moderate severity). Most common comorbids were hypertension(65%), diabetes mellitus(40%) and overweight(36%). Clinical progression to hypoxia was significantly lower in the treatment group (4%) compared to the control group (18%) (OR=0.190, 95% CI: 0.0618 - 0.583). Comparing case to control, the rates of ICU admission were 1% vs 3%, mechanical ventilation 0% vs 2% and inpatient mortality 2% vs 2%. 97% patients completed Ritonavir-boosted nirmatrelvir in the treatment group. CONCLUSION: Among high-risk hospitalised COVID-19 patients who received ritonavir-boosted nirmatrevir, they were 81% less likely to experience desaturation. Ritonavir-boosted Nirmatrelvir remains beneficial among highly vaccinated populations during the Omicron wave in COVID-19 pandemic.