3. Summary of characteristics of ongoing studies.

Study	Country	Design	Primary outcomes	Estimated number of participants	Estimated primary completion date
ACTRN12620000517976	Australia	RCT	Time to separation from invasive ventilation	172	25 July 2021
ChiCTR2000030700	China	RCT	Time to virus eradication	60	30 September 2020
ChiCTR2000030701	China	RCT	Time to virus eradication	60	30 September 2020
ChiCTR2000030946	China	Prospective cohort	Biochemical indicators	120	24 April 2020
Marietta 2020	Italy	RCT	Clinical worsening (includes death and necessity for additional respiratory support)	300	June 2021
NCT04333407	UK	RCT	All‐cause mortality at 30 days after admission	3170	30 March 2021
NCT04344756	France	RCT	Survival without ventilation	808	31 July 2020
NCT04345848	Switzerland	RCT	Composite outcome of arterial or venous thrombosis, disseminated intravascular coagulation and all‐cause mortality	200	30 November 2020
NCT04352400	Italy	RCT	Time to clinical improvement	256	December 2021
NCT04359277	USA	RCT	Composite incidence of: all‐cause mortality, cardiac arrest, symptomatic deep venous thrombosis, PE, arterial thromboembolism, myocardial infarction, stroke, or shock	1000	21 April 2021
NCT04360824	USA	RCT	Risk of all‐cause mortality	170	16 April 2021
NCT04362085	Canada	RCT	Composite outcome of ICU admission (yes/no), non‐invasive positive pressure ventilation (yes/no), invasive mechanical ventilation (yes/no), or all‐cause death (yes/no) up to 28 days	462	November 2020
NCT04366960	Italy	RCT	Incidence of VTE detected by imaging	2712	August 2020
NCT04367831	USA	RCT	Total number of patients with clinically relevant venous or arterial thrombotic events in ICU	100	November 2020
NCT04372589	Canada	RCT	Intubation and mortality	3000	January 2021
NCT04373707	France	RCT	VTE	602	September 2020
NCT04377997	USA	RCT	Risk of composite efficacy endpoint of death, cardiac arrest, symptomatic deep venous thrombosis, PE, arterial thromboembolism, myocardial infarction, or haemodynamic shock Risk of major bleeding event according to the ISTH definition	300	1 January 2021
NCT04393805	Italy	Retrospective cohort	Bleeding Thrombosis Mortality	877	December 2020
NCT04394377	Brazil	RCT	Hierarchical composite endpoint composed of mortality, number of days alive, number of days in the hospital and number of days with oxygen therapy at the end of 30 days	600	December 2020
NCT04397510	USA	RCT	Mean daily PaO2:FiO2	50	31 December 2020
NCT04401293	USA	RCT	Composite outcome of arterial thromboembolic events, venous thromboembolic events and all‐cause mortality at day 30 ± 2 days	308	22 October 2020
NCT04416048	Germany	RCT	Composite endpoint of VTE (DVT and/or fatal or non‐fatal PE), arterial thromboembolism, new myocardial infarction, non‐haemorrhagic stroke, all‐cause mortality or progression to intubation and invasive ventilation	400	30 April 2021
Total number of studies	Australia: 1 Brazil: 1 Canada: 2 China: 3 France: 2 Germany: 1 Italy: 4 Switzerland: 1 UK: 1 USA: 6	Prospective cohort: 1 RCT: 20 Retrospective cohort: 1	12 studies considered mortality Six studies considered additional respiratory support	15,727 participants 997 from NRS 14,730 from RCTs	13 studies to December 2020 8 studies to July 2021 1 study to December 2021
DVT: deep vein thrombosis; FiO2: fraction of inspired oxygen; ISTH: International Society on Thrombosis and Haemostasis; NRS: non‐randomised studies; PaO2: arterial oxygen pressure;PE: pulmonary embolism; RCT: randomised controlled trial; VTE: venous thromboembolism