Clinical Research Directory

Inclusion Criteria: As long as the patient meets all of the following conditions, adult patients aged 18 and above are eligible for admission: ► COVID-19 patients, defined as: positive RT-PCR (upper respiratory tract or lower respiratory tract) for SARS-CoV-2. Mild COVID-19 patients are defined as: Symptomatic patients meeting the case definition for COVID-19 without evidence of hypoxia or pneumonia. Common symptoms include fever, cough, fatigue, anorexia, dyspnea, and myalgia. Other nonspecific symptoms include sore throat, nasal congestion, headache, diarrhea, nausea/vomiting, and loss of smell/taste. Severe COVID-19 patients are defined as: Adolescents or adults with clinical signs of pneumonia (i.e., fever, cough, dyspnea, tachypnea) plus one of the following: 1. Respiratory rate ≥30 breaths/min 2. Severe respiratory distress 3. Oxygen saturation (SpO₂) ≤90% in room air 4. Progressive deterioration of clinical symptoms with lung imaging showing significant progression of lesions (\>50%) within 24 to 48 hours. * Written informed consent provided according to Chinese law (by the patient, legal guardian, or deferred consent in emergencies). Exclusion Criteria: Patients with any of the following conditions will be excluded from the study: * Pregnant or lactating women. * Postpartum (within 6 weeks). * Extreme weight (100 kilograms). * Clinical need for heparin therapy. * Bleeding related to coagulation disorders, acute clinically significant bleeding, active gastrointestinal ulcers, or any organic lesions with high bleeding risk. * Platelet count \<50 x 10\^9/L. * Surgery within the last 15 days, or within 24 hours after spinal or epidural anesthesia. * History of intracranial hemorrhage, large ischemic stroke, known intracranial malformation or tumor, acute infective endocarditis. * Severe renal impairment (creatinine clearance \<30 mL/min). * Iodine allergy. * Long-term use of oxygen supplementation. * Moribund patients or those expected to die during the current hospitalization due to underlying disease. * Patients deprived of freedom and those undergoing institutional psychiatric care. * Ward of the state or under guardianship. * Participation in other anticoagulant intervention studies.