inclusion criteria * patient/legally authorized representative has completed the informed consent form * age ≥18 years * ability to comply with the study protocol, in the investigator's judgment * respiratory failure secondary to covid-19 requiring mechanical ventilation for no greater than 24 hours, or high-flow nasal cannula (hfnc),non-rebreather (nrb) mask or non-invasive positive pressure ventilation (nippv) for no greater than 48 hours * confirmed infection with sars-cov-2 virus (pcr positive within 14 days) * elevated d-dimer (\>6 times upper limit of normal within past 72 hours) * for patient who are intubated \>12 hours prior to randomization or with any evidence of neurologic deficit a head ct within 12 hours demonstrating no evidence of acute or subacute infarct or hemorrhage exclusion criteria * current participation in another investigational drug study within the prior 7 days * known hypersensitivity or allergy to any ingredients of tenecteplase * active internal bleeding * known bleeding diathesis * use of one of the new oral anticoagulants within the last 48 hours (dabigatran, rivaroxaban, apixaban, edoxaban) * treatment with a thrombolytic within the last 3 months prior to randomization (exception for the use of cathflo alteplase for occlusions of central venous catheters) * baseline platelet count \<80,000/l (results must be available prior to treatment) * baseline blood glucose \>400 mg/dl (22.20 mmol/l) * baseline blood glucose \<50 mg/dl needs to be normalized prior to randomization * intracranial or intraspinal surgery or trauma within 2 months * other, non-covid-19 related, serious, advanced, or terminal illness (investigator judgment) or life expectancy is less than 6 months * history of acute ischemic stroke in the last 90 days * history of intracranial bleeding, including hemorrhagic stroke * presumed septic embolus; suspicion of bacterial endocarditis * mechanical ventilation \> 24 hours, hfnc, nrb, nippv, or any combination, for greater than 48 hours * mechanical ventilation, hfnc, nrb, or nipvv (for reasons other than obstructive sleep apnea) within the prior 30 days (excluding 48 hours prior to randomization) * moribund status suggesting imminent vascular collapse and inability to survive \> 72 hours (investigator determination) * uncontrolled hypertension defined as systolic bp \> 180 mm hg and/or diastolic bp \> 110 mm hgb * age \> 75 years * history of traumatic brain injury within 2 months * recent head trauma with fracture or brain injury * history of heparin induced thrombocytopenia (hit) and/or other hereditary or acquired hemorrhagic diathesis or coagulation factor deficiency * inr \> 2 or recent oral anticoagulant therapy with inr \>1.7 * pregnancy or lactation within the prior 30 days; women of childbearing age (\<55 years old) should have documentation of a negative pregnancy test * chronic liver disease defined as \> childs-pugh class b * atrial fibrillation, mitral stenosis, or known left heart thrombosis * any other condition that, in the opinion of the investigator, precludes administration of tenecteplase or poses a significant hazard to the patient receives tenecteplase

inclusion criteria * patient/legally authorized representative has completed the informed consent form * age ≥18 years * ability to comply with the study protocol, in the investigator's judgment * respiratory failure secondary to covid-19 requiring mechanical ventilation for no greater than 24 hours, or high-flow nasal cannula (hfnc),non-rebreather (nrb) mask or non-invasive positive pressure ventilation (nippv) for no greater than 48 hours * confirmed infection with sars-cov-2 virus (pcr positive within 14 days) * elevated d-dimer (\>6 times upper limit of normal within past 72 hours) * for patient who are intubated \>12 hours prior to randomization or with any evidence of neurologic deficit a head ct within 12 hours demonstrating no evidence of acute or subacute infarct or hemorrhage exclusion criteria * current participation in another investigational drug study within the prior 7 days * known hypersensitivity or allergy to any ingredients of tenecteplase * active internal bleeding * known bleeding diathesis * use of one of the new oral anticoagulants within the last 48 hours (dabigatran, rivaroxaban, apixaban, edoxaban) * treatment with a thrombolytic within the last 3 months prior to randomization (exception for the use of cathflo alteplase for occlusions of central venous catheters) * baseline platelet count \<80,000/l (results must be available prior to treatment) * baseline blood glucose \>400 mg/dl (22.20 mmol/l) * baseline blood glucose \<50 mg/dl needs to be normalized prior to randomization * intracranial or intraspinal surgery or trauma within 2 months * other, non-covid-19 related, serious, advanced, or terminal illness (investigator judgment) or life expectancy is less than 6 months * history of acute ischemic stroke in the last 90 days * history of intracranial bleeding, including hemorrhagic stroke * presumed septic embolus; suspicion of bacterial endocarditis * mechanical ventilation \> 24 hours, hfnc, nrb, nippv, or any combination, for greater than 48 hours * mechanical ventilation, hfnc, nrb, or nipvv (for reasons other than obstructive sleep apnea) within the prior 30 days (excluding 48 hours prior to randomization) * moribund status suggesting imminent vascular collapse and inability to survive \> 72 hours (investigator determination) * uncontrolled hypertension defined as systolic bp \> 180 mm hg and/or diastolic bp \> 110 mm hgb * age \> 75 years * history of traumatic brain injury within 2 months * recent head trauma with fracture or brain injury * history of heparin induced thrombocytopenia (hit) and/or other hereditary or acquired hemorrhagic diathesis or coagulation factor deficiency * inr \> 2 or recent oral anticoagulant therapy with inr \>1.7 * pregnancy or lactation within the prior 30 days; women of childbearing age (\<55 years old) should have documentation of a negative pregnancy test * chronic liver disease defined as \> childs-pugh class b * atrial fibrillation, mitral stenosis, or known left heart thrombosis * any other condition that, in the opinion of the investigator, precludes administration of tenecteplase or poses a significant hazard to the patient receives tenecteplase

inclusion criteria - patient/legally authorized representative has completed the informed consent form - age ≥18 years - ability to comply with the study protocol, in the investigator's judgment - respiratory failure secondary to covid-19 requiring mechanical ventilation for no greater than 24 hours, or high-flow nasal cannula (hfnc),non-rebreather (nrb) mask or non-invasive positive pressure ventilation (nippv) for no greater than 48 hours - confirmed infection with sars-cov-2 virus (pcr positive within 14 days) - elevated d-dimer (>6 times upper limit of normal within past 72 hours) - for patient who are intubated >12 hours prior to randomization or with any evidence of neurologic deficit a head ct within 12 hours demonstrating no evidence of acute or subacute infarct or hemorrhage exclusion criteria - current participation in another investigational drug study within the prior 7 days - known hypersensitivity or allergy to any ingredients of tenecteplase - active internal bleeding - known bleeding diathesis - use of one of the new oral anticoagulants within the last 48 hours (dabigatran, rivaroxaban, apixaban, edoxaban) - treatment with a thrombolytic within the last 3 months prior to randomization (exception for the use of cathflo alteplase for occlusions of central venous catheters) - baseline platelet count <80,000/l (results must be available prior to treatment) - baseline blood glucose >400 mg/dl (22.20 mmol/l) - baseline blood glucose <50 mg/dl needs to be normalized prior to randomization - intracranial or intraspinal surgery or trauma within 2 months - other, non-covid-19 related, serious, advanced, or terminal illness (investigator judgment) or life expectancy is less than 6 months - history of acute ischemic stroke in the last 90 days - history of intracranial bleeding, including hemorrhagic stroke - presumed septic embolus; suspicion of bacterial endocarditis - mechanical ventilation > 24 hours, hfnc, nrb, nippv, or any combination, for greater than 48 hours - mechanical ventilation, hfnc, nrb, or nipvv (for reasons other than obstructive sleep apnea) within the prior 30 days (excluding 48 hours prior to randomization) - moribund status suggesting imminent vascular collapse and inability to survive > 72 hours (investigator determination) - uncontrolled hypertension defined as systolic bp > 180 mm hg and/or diastolic bp > 110 mm hgb - age > 75 years - history of traumatic brain injury within 2 months - recent head trauma with fracture or brain injury - history of heparin induced thrombocytopenia (hit) and/or other hereditary or acquired hemorrhagic diathesis or coagulation factor deficiency - inr > 2 or recent oral anticoagulant therapy with inr >1.7 - pregnancy or lactation within the prior 30 days; women of childbearing age (<55 years old) should have documentation of a negative pregnancy test - chronic liver disease defined as > childs-pugh class b - atrial fibrillation, mitral stenosis, or known left heart thrombosis - any other condition that, in the opinion of the investigator, precludes administration of tenecteplase or poses a significant hazard to the patient receives tenecteplase

inclusion criteria - patient/legally authorized representative has completed the informed consent form - age ≥18 years - ability to comply with the study protocol, in the investigator's judgment - respiratory failure secondary to covid-19 requiring mechanical ventilation for no greater than 24 hours, or high-flow nasal cannula (hfnc),non-rebreather (nrb) mask or non-invasive positive pressure ventilation (nippv) for no greater than 48 hours - confirmed infection with sars-cov-2 virus (pcr positive within 14 days) - elevated d-dimer (>6 times upper limit of normal within past 72 hours) - for patient who are intubated >12 hours prior to randomization or with any evidence of neurologic deficit a head ct within 12 hours demonstrating no evidence of acute or subacute infarct or hemorrhage exclusion criteria - current participation in another investigational drug study within the prior 7 days - known hypersensitivity or allergy to any ingredients of tenecteplase - active internal bleeding - known bleeding diathesis - use of one of the new oral anticoagulants within the last 48 hours (dabigatran, rivaroxaban, apixaban, edoxaban) - treatment with a thrombolytic within the last 3 months prior to randomization (exception for the use of cathflo alteplase for occlusions of central venous catheters) - baseline platelet count <80,000/l (results must be available prior to treatment) - baseline blood glucose >400 mg/dl (22.20 mmol/l) - baseline blood glucose <50 mg/dl needs to be normalized prior to randomization - intracranial or intraspinal surgery or trauma within 2 months - other, non-covid-19 related, serious, advanced, or terminal illness (investigator judgment) or life expectancy is less than 6 months - history of acute ischemic stroke in the last 90 days - history of intracranial bleeding, including hemorrhagic stroke - presumed septic embolus; suspicion of bacterial endocarditis - mechanical ventilation > 24 hours, hfnc, nrb, nippv, or any combination, for greater than 48 hours - mechanical ventilation, hfnc, nrb, or nipvv (for reasons other than obstructive sleep apnea) within the prior 30 days (excluding 48 hours prior to randomization) - moribund status suggesting imminent vascular collapse and inability to survive > 72 hours (investigator determination) - uncontrolled hypertension defined as systolic bp > 180 mm hg and/or diastolic bp > 110 mm hgb - age > 75 years - history of traumatic brain injury within 2 months - recent head trauma with fracture or brain injury - history of heparin induced thrombocytopenia (hit) and/or other hereditary or acquired hemorrhagic diathesis or coagulation factor deficiency - inr > 2 or recent oral anticoagulant therapy with inr >1.7 - pregnancy or lactation within the prior 30 days; women of childbearing age (<55 years old) should have documentation of a negative pregnancy test - chronic liver disease defined as > childs-pugh class b - atrial fibrillation, mitral stenosis, or known left heart thrombosis - any other condition that, in the opinion of the investigator, precludes administration of tenecteplase or poses a significant hazard to the patient receives tenecteplase