Table 1.

WHO Clinical Progression Scale

Patient state	Descriptor	Score
Uninfected	Uninfected; no viral RNA detected	0
Ambulatory	Asymptomatic; viral RNA detected	1
	Symptomatic; independent	2
	Symptomatic; assistance needed	3
Hospitalised; mild disease	Hospitalised; no oxygen therapy	4
	Hospitalised; oxygen by mask or nasal prongs	5
Hospitalised; severe disease	Hospitalised; oxygen by NIV or high flow	6
	Intubated and mechanical ventilation, pO2/FiO2>150 or SpO2/FiO2>200	7
	Mechanical ventilation pO2/FiO2<150 (SpO2/FiO2<200) or vasopressors	8
	Mechanical ventilation pO2/FiO2<150 (SpO2/FiO2<200) and vasopressors, dialysis or ECMO	9
Death	Dead	10

Adapted from reference 29.

Footnotes for use in CATALYST. (1) If pO₂ not available then use the SpO₂/FiO₂ ratio instead. (2). For pO₂ measurements in kPa, use an online calculator, for example, https://www.msdmanuals.com/en-gb/medical-calculators/PaO2_FiO2Ratio.htm to calculate a pO₂/FiO₂ ratio equivalent to that obtained with pO₂ measured in mm Hg, or else consider an equivalent ratio to 200, when dividing pO₂ in kPa by FiO₂, is 26.7, and an equivalent to 150 is 20. (3). If medically fit for discharge, record status as for ambulatory patient. (4). Asymptomatic implies a return to baseline symptomatic state that is, no fever, and no cough, shortness of breath, confusion, myalgia, diarrhoea, fatigue or weakness above what the participant would have experienced on a daily basis before their COVID-19 episode. (5). Symptomatic but independent, implies that the participant has some of the additional symptoms as above, but needs no additional help with activities of daily living above what they required prior to their COVID-19 episode. (6). Symptomatic but needs assistance, implies that in addition to having symptoms as above, they require help with activities of daily living that is, bathing/showering, personal hygiene and combing of hair, dressing, toileting, mobility/transferring and self-feeding, above what they required on a daily basis prior to their COVID-19 episode. (7). Score 0 (uninfected: no viral RNA detected) is not being assessed as part of CATALYST.

ECMO, extracorporeal membrane oxygenation; NIV, non-invasive ventilation; pO₂, partial pressure of oxygen; SpO2/FiO2, oxygen saturation to fractional inspired oxygen concentration.