786. Effect of Nirmatrelvir/Ritonavir versus Placebo on COVID-19─Related Hospitalizations and Other Medical Visits

Abstract Background Nirmatrelvir coadministered with ritonavir (nirmatrelvir/r) is a COVID-19 treatment. This study evaluated nirmatrelvir/r in nonhospitalized, symptomatic adults with COVID-19 at high risk of progressing to severe disease. We report secondary efficacy endpoints associated with COVID-19─related medical visits, including hospitalization details and oxygen support, as of the primary completion data cutoff (Dec 11, 2021). Methods In this phase 2/3 double-blind, interventional study, adults with confirmed SARS-CoV-2 and symptom onset ≤ 5 days (d) were randomized 1:1 to receive nirmatrelvir/r 300 mg/100 mg or placebo (PBO) orally every 12 hours for 5 d. COVID-19─related medical visits were collected through Day 28. Oxygen support for COVID-19 and details of COVID-19─related hospitalization, including duration, intensive care unit (ICU) status, and mechanical ventilation, were assessed. Results Of the 2246 patients (pts) enrolled globally from Jul to Dec2021, 2085 (nirmatrelvir/r, n=1039; PBO, n=1046) started treatment and met criteria for the modified intent-to-treat population (mITT1; ≤ 5 d of symptom onset, did not/not expected to receive a mAb). Fewer overall COVID-19-related medical visits were reported with nirmatrelvir/r vs PBO (Table 1). In addition to fewer hospitalizations being reported with nirmatrelvir/r (n=8 [0.8%]) vs PBO (n=65 [6.2%]), pts receiving nirmatrelvir/r had fewer hospitalized d (Table 2), with mean durations of 9.6 (range, 5.0, 16.0) d with nirmatrelvir/r and 11.2 (range, 2.0, 57.0) d with PBO in hospitalized pts. No pts in the nirmatrelvir/r group and 9 pts (0.9%) in PBO group were admitted to the ICU. No pts in the nirmatrelvir/r group received mechanical ventilation vs 3 pts in the PBO group. Fewer other COVID-19─related nonhospital medical visits were reported with nirmatrelvir/r vs PBO (Table 3). In the full analysis set, fewer pts required oxygen therapy for COVID-19 with nirmatrelvir/r (n=9/1120 [0.8%]) vs PBO (n=54/1126 [4.8%]). Conclusion High-risk adults with symptomatic COVID-19 treated with nirmatrelvir/r within 5 d of symptom onset had fewer COVID-19─related medical visits and reduced healthcare utilization (no ICU visits, no mechanical ventilation, fewer days in hospital) vs pts receiving PBO. Clinical Trial: NCT04960202. Disclosures Jennifer Hammond, PhD, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Heidi Leister-Tebbe, BSN, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Annie Gardner, MPH, MSPT, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Paula Abreu, PhD, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Weihang Bao, PhD, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Wayne Wisemandle, MA, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Wajeeha Ansari, MPH, Pfizer Inc.: Stocks/Bonds Rienk Pypstra, MD, MBA, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds James M Rusnak, MD, PhD, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds.