The study is a multicenter, adaptive, randomized, double-blinded and placebo-controlled Phase II/III clinical trial. It will be conducted at selected investigational sites globally. The study is comprised of 2 parts.

The study is a multicenter, adaptive, randomized, double-blinded, and placebocontrolled Phase II/III trial. It will be conducted globally. The study will evaluate the efficacy and safety of SCTA01 in high-risk outpatients with COVID-19.The primary objective of the study is to evaluate the clinical efficacy rate among study group [SCTA01+ standard of care (SOC)] and control group (placebo + SOC) up to Day 29.

Inclusion Criteria:

• Male or non-pregnant female adults, ≥18 years old of age at the time of randomization;
• Participants should have at least one of COVID-19 risk factor;
• Participants should have at least 2 COVID-19 related symptoms;
• Has symptoms consistent with COVID-19 as determined by the investigator with onset ≤7 days before randomization;
• First positive SARS-CoV-2 viral infection tested (PCR or antigen-based diagnostic tests) in samples collected ≤3 days prior to start of the infusion;
• Participants are currently not hospitalized;
• Participant (or legal authorized representative) has signed the ICF before any clinical activity related to SCTA01 trial;
• Women with childbearing potential must agree to use effective contraceptive methods during the study period;
• Patient should not participate in other clinical studies related to COVID-19 or SARS-CoV-2 infection.

Exclusion Criteria:

• Have known allergies to any of the components used in the formulation of the SCTA01/placebo;
• Participants with a history of severe anaphylaxis, such as severe anaphylactic reaction, urticaria, and angioedema;
• Have SpO2 ≤ 93% on room air at sea level or PaO2/FiO2 < 300, respiratory rate ≥30 per minute, heart rate ≥125 per minute (FDA);
• Require mechanical ventilation or anticipated impending need for mechanical ventilation;
• Suspected or proven serious bacterial, fungal, viral, or other infection (besides COVID-19) that in the opinion of the investigator could constitute a risk when taking part in this study;
• Have any serious concomitant systemic disease, condition or disorder that, in the opinion of the investigator, should preclude participation in this study;
• Have any co-morbidity requiring surgery within <29 days, or that is considered life threatening within 29 days;
• Have a history of previous SARS-CoV-2 infection;
• Received convalescent plasma, COVID-19 vaccine, or anti-SARS-CoV-2 spike(S) protein targeted therapy;
• Have participated in a clinical study involving an investigational intervention within past 30 days or 5-half lives of investigational product, whichever is longer;
• Have received an investigational intervention for SARS-CoV-2 prophylaxis within 30 days before dosing;
• Pregnant or lactating women;
• Anticipated hospitalization or transfer to another medical site which is not a study site within 72 hours;
• Participants unable to follow the protocol during the study;
• Participants deemed inappropriate for enrollment by the investigator due to other factors.