Preventing COVID-19 Complications With Low- and High-dose Anticoagulation

Inclusion Criteria: adult patient with COVID-19 infections, admitted to: * an acute non-critical medical ward with admission D-dimer levels \>1,000ng/mL, or * an acute critical ward (ICU, intermediate care unit) Exclusion Criteria: * ongoing or planned therapeutic anticoagulation for any other indication * contra-indication to therapeutic anticoagulation * hypersensitivity to heparin * personal history of heparin-induced thrombocytopenia * suspected or confirmed bacterial endocarditis * bleeding events or tendency due to a suspected or confirmed hemostatic bleeding disorder * organic lesion prone to bleeding * platelet count \<50G/L, Hb level \<80g/L * ongoing or recent (\<30 days) major bleeding, ischemic stroke, trauma, surgery * use of dual antiplatelet therapy * pregnancy * bodyweight \<40kg or \>150kg. * end of life care setting * unwillingness to consent * ongoing participation in a COVID-19 randomized clinical trial testing another therapeutic intervention