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 for non-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 study period and within 4 months following the last dose, and agrees to use appropriate and 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 improved within the first 48 hours prior to the initial dosing (predictable improvement in oxygenation 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 Pneumocystis jirovecii 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 severe underlying 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 3 months prior to screening;
21. Any condition that the investigator believes may increase the risk to the patient or interfere with the execution of the clinical trial;
22. Known allergy to any component of the investigational drug or its excipients, or a history of hypersensitivity (e.g., allergic to two or more drugs);
23. Any other disease or condition that, in the investigator's opinion, makes the patient unsuitable for participation in this study;