Inclusion Criteria:

A potential participant must have met all the following criteria to be included in the
study:

1. Was hospitalized for laboratory-documented Coronavirus Disease 2019 (COVID-19) (e.g.,
positive for severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] via
nasopharyngeal swab real time polymerase chain reaction [RT-PCR; or other commercial
or public health assay]).

2. Was aged ≥18 years and ≤85 years.

3. Had a resting oxygen saturation (SaO2) of <94% while breathing ambient air.

4. Had a score of 3 or 4 on the National Institute of Allergy and Infectious Diseases
(NIAID) ordinal scale (required supplemental oxygen or non-invasive ventilation).

5. Had provided informed consent to participate in the study (by participant or
legally-acceptable representative).

Exclusion Criteria:

A potential participant who met any of the following criteria was not eligible to
participate in the study:

1. Was currently receiving invasive mechanical ventilation (e.g., via an endotracheal
tube) (score of 2 on NIAID ordinal scale).

2. Had severe chronic respiratory disease, defined by any oxygen requirement prior to
incident COVID-19.

3. Had active or uncontrolled bleeding at the time of randomization; a bleeding disorder,
either inherited or caused by disease; history of known arterial-venous malformation,
intracranial hemorrhage, or suspected or known cerebral aneurysm; or clinically
significant (in the judgment of the Investigator) gastrointestinal bleeding within the
3 weeks prior to randomization.

4. Was receiving any other investigational (non-approved) therapy for the treatment of
COVID-19 or participating in the treatment period of any other therapeutic
intervention clinical study. Participating in the follow-up period of an
interventional study may be permitted with prior medical monitor approval;
participation in an observational study is permitted.

5. Was receiving systemic corticosteroids for a chronic condition.

6. Was receiving chronic anticoagulation with warfarin or direct oral anticoagulants
(e.g., rivaroxaban, dabigatran, apixaban, edoxaban).

7. Was receiving or anticipated to require other systemic anticoagulation dosing at a
therapeutic intensity. Prophylaxis of venous thromboembolism (VTE) using subcutaneous
(SC) unfractionated heparin or enoxaparin was permitted with appropriate monitoring of
coagulation status and within the guidelines described in the protocol.

8. Was receiving antiplatelet therapy, alone or in combination, including aspirin and
other antiplatelet agents (e.g., clopidogrel, ticagrelor, and prasugrel), unless able
to discontinue these agents at the time of randomization and was able to remain off
these agents throughout the duration of the study intervention infusion period.

9. Had treatment with systemic (non-steroid) immunomodulators or immunosuppressant
medications, including but not limited to tumor necrosis factor (TNF) inhibitors,
anti-interleukin-1 agents and Janus kinase (JAK) inhibitors within 5 half-lives or 30
days (whichever was longer) prior to randomization.

10. Had a history of congestive heart failure requiring hospitalization.

11. Had active pericarditis (based on clinical assessment).

12. Had malignancy or other irreversible disease or condition for which 6-month mortality
was estimated ≥50%.

13. Had a corrected QT interval (QTc) >500 msec (or >530-550 msec in participants with QRS
greater than >120 msec).

14. Had a Tisdale risk score ≥11 without the ability to monitor with serial
electrocardiograms (ECGs) or telemetry.

15. Had severe renal impairment, as determined by calculated creatinine clearance <30
mL/min or estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m2.

16. Had alanine aminotransferase (ALT) or aspartate aminotransferase (AST) values >5x
upper limit of normal (ULN).

17. Had activated partial thromboplastin time (aPTT) >42 seconds.

18. Had thrombocytopenia with a platelet count <80,000/mm3.

19. Had severe chronic liver disease (Child-Pugh Score of 10 to 15).

20. Had received dociparstat in a different clinical study.

21. Woman of childbearing potential who was pregnant, breastfeeding, and/or not using a
highly-effective method of contraception (consistent with local regulations regarding
the methods of contraception for those participating in clinical studies).

22. Had evidence of clinical improvement in COVID-19 status including, but not limited to,
a sustained reduction in oxygen requirements over the previous 48 hours, or extubated
and/or no longer requiring mechanical ventilation following intubation for COVID-19.

23. Had any other condition, including abnormal laboratory values, that, in the judgment
of the Investigator, could have put the participant at increased risk, or would have
interfered with the conduct or planned analysis of the study.