To Evaluate The Safety and Initial Efficacy of STSA-1002 Injection in Patients With Acute Respiratory Distress Syndrome

Inclusion Criteria:

1. 18 years old≤Age≤85 years old;

2. Pathogen results indicate respiratory viral infection;

3. Acute respiratory distress syndrome (ARDS) caused by viral pneumonia;

4. In 14haode days since the onset of respiratory infective symptoms (in 12 days fornon-invasive mechanical ventilation patients);

5. PaO₂/FiO₂ ≤200 mmHg based on arterial blood gas analysis prior to randomization;

6. Most recent peripheral blood lymphocyte count ≤0.8×10^9/L prior to randomization;

7. Patients (including patients' partners) has no plans for conception during the studyperiod and within 4 months following the last dose, and agrees to use appropriateand effective contraception (e.g., birth control pills, condoms);

8. Willing to participate in the study and signs the informed consent form

Exclusion Criteria:

1. Use of ECMO before the first administration;

2. More than 48 hours of invasive mechanical ventilation prior to the first dose;

3. Based on the researchers' overall assessment, the patient's condition improvedwithin the first 48 hours prior to the initial dosing (predictable improvement inoxygenation indicators observed within the next 48 hours);

4. Expected survival period of less than 24 hours or a history of cardiac arrest within 4 weeks prior to screening;

5. Recent history of stroke or acute coronary syndrome;

6. Diagnosed with fungal pneumonia (Aspergillus, Mucor, Cryptococcus, or Pneumocystisjirovecii pneumonia);

7. Suspected or known cytomegalovirus infection;

8. Suspected or known active tuberculosis;

9. Experienced prolonged fluid resuscitation-resistant septic shock.

10. Severe chronic respiratory failure;

11. Deemed by the investigator as difficult to wean from ventilation due to severeunderlying diseases;

12. Cardiogenic pulmonary edema or congestive heart failure;

13. Liver dysfunction;

14. Severe renal impairment or long-term dialysis;

15. Immunocompromised state;

16. A Absolute neutrophil count is excessively low;

17. Severe anemia or active bleeding;

18. Poor compliance with standard treatment;

19. Pregnant or breastfeeding women;

20. Participated in a clinical trial of a new drug and received treatment within 3months prior to screening;

21. Any condition that the investigator believes may increase the risk to the patient orinterfere with the execution of the clinical trial;

22. Known allergy to any component of the investigational drug or its excipients, or ahistory of hypersensitivity (e.g., allergic to two or more drugs);

23. Any other disease or condition that, in the investigator's opinion, makes thepatient unsuitable for participation in this study;