In this JACC review article, researchers provide a comprehensive summary of all anticoagulant studies involving COVID-19 patients to date. It also details a large-scale, international, clinical trial led by Mount Sinai Health System in NYC called “FREEDOM COVID-19 Anticoagulation Trial.” Investigators are enrolling up to 3,600 hospitalized COVID-19 patients not requiring care in the intensive care unit, to find out which anticoagulation regimen is most effective in preventing clotting that may lead to heart attack and stroke. Clinical, laboratory and autopsy findings support an association between COVID-19 and thromboembolic events. In this unique trial, patients are being randomized to a blood thinner regimen of prophylactic-dose enoxaparin vs. therapeutic-dose enoxaparin vs. therapeutic-dose apixaban. The primary outcome is the composite of all-cause mortality, requirement for ICU level of care, or thromboembolic events.