Efficacy and Safety Study of BDB-001 in Severe COVID-19 With ALI/ARDS

Inclusion Criteria:

1. 18 years old ≤ age ≤ 80 years old, both men or women.

2. Confirmed SARS-CoV-2 infection, and meet at least one of the following criteria:

Confirmed severe COVID-19 in no more than 5 days who meets any of the following
criteria:

1. Respiratory distress, RR ≥ 30 times/min

2. Finger oxygen saturation (SpO2) ≤93% in resting state(room air)

3. Arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) ≤
300 mmHg (1 mmHg = 0.133kpa) in supine position

4. Pulmonary imaging shows lesion progression > 50% within 24-48 hours.

Symptoms,signs or chest imaging indicates ALI/ARDS;

3. Requiring a mask oxygen therapy,high-flow nasal cannula oxygen therapy(HFNC).

4. The informed consent form signed.

Exclusion Criteria:

Subject who meets any of the following criteria will be excluded from the trial:

1. Subjects already progressed into critically severe COVID-19 Critical severe standards
refer to FDA guidelines,as shown in Appendix 4 or sepsis and sepsis shock.

2. Concomitant with the following situation:severe lung disease such as chronic
obstructive pulmonary disease (moderate to severe type), lung cancers, active
tuberculosis; severe cardiovascular and cerebrovascular disease: unstable angina
pectoris, myocardial infarction, postcardiac surgery, cardiac function ≥ grade 3 (NYHA
Classification), or had undergone heart surgery within 6 months before randomization;
severe liver diseases (e.g. Child-Pugh score ≥ grade C); severe kidney diseases, such
as renal insufficiency (GFR ≤ 15 mL/min/1.73m^2); immune deficiencies or
immune-related diseases : including organ or bone marrow transplantation, some
autoimmune diseases, IgG4-related diseases, allergic alveolitis, vasculitis;
malignancies.

3. Subjects on current treatment with a complement inhibitor such as eculizumab within 1
month before randomization.

4. Subjects with hypersensitivity history to any ingredient contained in the drug.

5. A subject has used the following drugs within 2 weeks prior to screening procedures:

- Calcineurin inhibitors (e.g., ciclosporin, tacrolimus, etc.)

- Proliferation inhibitors (e.g., everolimus, sirolimus, etc.)

- Anti-metabolic drugs (e.g., mycophenolate mofetil, mycophenolate, purine
sulphate, etc.)

- Recombinant human granulocyte macrophage colony stimulating factor
(rhGM-CSF)/recombinant human granulocyte colony stimulating factor (rhG-CSF)

6. Pregnant or lactating woman.

7. Subjects who have participated in other interventional clinical trials in the last 3
months or during this trial.

8. Any other circumstances that the investigator considers inappropriate for the
participation in this study.