Inclusion criteria  Hospitalized for COVID-19 ≥18 years of age  SARS-CoV-2 infection, documented by:  a nucleic acid test (NAT) or equivalent testing within 3 days prior to randomization OR documented by NAT or equivalent testing more than 3 days prior to randomization AND progressive disease suggestive of ongoing SARS-CoV-2 infection per the responsible investigator (For non-NAT tests, only those deemed with equivalent specificity to NAT by the protocol team will be allowed. A central list of allowed non- NAT tests is maintained in in the study protocol) Hypoxemia, defined as SpO2 <92% on room air, new receipt of supplemental oxygen to maintain SpO2 ≥92%, or increased supplemental oxygen to maintain SpO2 ≥92% for a patient on chronic oxygen therapy  Symptoms or signs of acute COVID-19, defined as one or more of the following:  cough reported or documented body temperature of 100.4 degrees Fahrenheit or greater shortness of breath chest painTXA127-specific exclusion criter infiltrates on chest imaging (x-ray, CT scan, lung ultrasound)  Exclusion criteria  COVID-19 symptom onset >14 days prior to randomization Hospitalized for >72 hours prior to randomization Pregnancy Breastfeeding Prisoners End-stage renal disease (ESRD) on dialysis Patient and/or clinical team is not pursuing full medical management (if a patient has a Do Not Resuscitate order that precludes chest compressions in the event of a cardiac arrest but is otherwise pursuing full medical management, he/she is eligible for this trial). The treating clinician expects inability to participate in study procedures or participation would not be in the best interests of the patient  The following exclusion criteria differ from the master protocol criteria:  TXA127-specific exclusion criteria:  Patient unable to participate or declines participation in the TXA127/Ang(1-7) arm. History of sensitivity (including angioedema) or allergic reaction to medication targeting the RAAS system including study medications or other allergy in the opinion of the investigator that contraindicates participation (not applicable to fostamatinib arm) Hemodynamic instability - defined as MAP < 65 mmHg at time of randomization confirmed on two measurements 5 minutes apart OR vasopressors at or above norepinephrine equivalent of 0.1 mcg/kg/min in prior 4 hours to maintain MAP > 65 mmHg. Known severe renal artery stenosis. Known significant left ventricular outflow obstruction, such as obstructive hypertrophic cardiomyopathy or severe aortic or mitral stenosis. Randomized in another trial evaluating RAAS modulation in the prior 30 days  TRV027-specific exclusion criteria:  Participants on ARBs will be excluded from this study arm. Patient unable to participate or declines participation in the TRV027 arm. History of sensitivity (including angioedema) or allergic reaction to medication targeting the RAAS system including study medications or other allergy in the opinion of the investigator that contraindicates participation (not applicable to fostamatinib arm) Hemodynamic instability - defined as MAP < 65 mmHg at time of randomization confirmed on two measurements 5 minutes apart OR vasopressors at or above norepinephrine equivalent of 0.1 mcg/kg/min in prior 4 hours to maintain MAP > 65 mmHg. Known severe renal artery stenosis. Known significant left ventricular outflow obstruction, such as obstructive hypertrophic cardiomyopathy or severe aortic or mitral stenosis. Randomized in another trial evaluating RAAS modulation in the prior 30 days  Fostamatinib specific exclusion criteria:  AST or ALT ≥ 5 × upper limit of normal (ULN) or ALT or AST ≥ 3 × ULN and total bilirubin ≥ 2 × ULN SBP > 160 mmHg or DBP > 100 mmHg at the time of screening and randomization ANC < 1000/mL Patient requires use of strong CYP3A modulators from Table above (Clarithromycin, Indinavir, Itraconazole, Ketoconazole, Nefazodone, Nelfinavir, Ritonavir, Saquinavir, Telithromycin, Troleandomycin, Carbamazepine, Efavirenz, Enzalutamide, Modafinil, Nevirapine, Oxcarbazepine, Phenobarbital, Phenytoin, Rifabutin, Rifampin, St. John's Wort, or Troglitazone). Patient unable to participate or declines participation in the fostamatinib arm.