This is a Randomized, double-blind, Placebo-Controlled, Phase II Clinical Study to evaluate SSD8432 in combination with Ritonavir in asymptomatic infections or mild/common safety study of efficacy and safety in adult subjects with COVID-19.

This is a Randomized, double-blind, Placebo-Controlled, Phase II Clinical Study to evaluate SSD8432 in combination with Ritonavir in asymptomatic infections or mild/common safety study of efficacy and safety in adult subjects with COVID-19.

This study planned to enroll 72 subjects, randomly divided into low-dose group, high-dose group and placebo group according to 1:1:1.

Inclusion Criteria:

1. ≥18 and ≤80 years old, male or female.
2. Asymptomatic infection,mild or common type of COVID-19.
3. Initial positive test of SARS-CoV-2 within 5 days of randomization.
4. Initial onset of COVID-19 signs/symptoms within 3 days of randomization.

Exclusion Criteria:

1. Transnasal high-flow oxygen therapy or non-invasive ventilation, invasive mechanical ventilation, or ECMO is required or anticipated to be urgently required.
2. Prior to current disease episode, any confirmed SARS-CoV-2 infection.
3. Known medical history of active liver disease (other than nonalcoholic hepatic steatosis).
4. Receiving dialysis or have known moderate to severe renal impairment.
5. Known human immunodeficiency virus (HIV) infection.
6. Suspected or confirmed concurrent active systemic infection other than COVID-19 that may interfere with the evaluation of response to the study intervention.
7. Oxygen saturation of ≤ 93% on room air obtained at rest within 24 hours prior to randomization..
8. Treatment with antivirals against SARS-CoV-2 within 14 days.
9. Current or expected use of any medications or substances that are highly dependent on CYP3A4 for clearance.
10. Concomitant use of any medications or substances that are strong inducers of CYP3A4 are prohibited within 28 days.
11. Has received or is expected to receive COVID-19 monoclonal antibody, convalescent COVID-19 plasma or other prohibited concomitant medication.
12. Females who are pregnant or breastfeeding.