Study to Assess the Efficacy and Safety of STI-1558 in Adult Subjects With Mild or Moderate (COVID-19)

STI-1558 will be orally administered under fasting condition twice daily (BID) for 5 days (10 doses in total) at a dose of 600 mg, respectively; the two doses administered will be at a minimum interval of 8 hours (≥8 h). Efficacy and safety will be assessed until D29 after the first dose.

STI-1558 placebo will be orally administered under fasting condition twice daily (BID) for 5 days (10 doses in total) at a dose of 0 mg, respectively; the two doses administered will be at a minimum interval of 8 hours (≥8 h). Efficacy and safety will be assessed until D29 after the first dose.