Table 2.

Clinical significance of coronavirus disease-2019

Stage	Symptoms
Mild	Initial symptoms are mild or negligible with no sign of pneumonia on imaging.
Moderate	Cough, moderate fever, myalgia, gastrointestinal symptoms, anosmia and respiratory signs with radiological imaging findings of pneumonia.
Severe	The presence of one of the following: (1) Shortness of breath (RR ≥ 30 breaths/min); (2) Oxygen saturation ≤ 93% at rest; (3) Arterial partial pressure of oxygen/fraction of inspired oxygen ≤ 300 mmHg (l mmHg = 0.133 kPa); and (4) In less than 24-48 h, more than half of patients with radiological imaging show clear lesion progression.
Critical	Any of the following: (1) Lung failure or requiring mechanical ventilation; (2) Septic shock; and (3) Multiple organ failure (other organ failure that requires HDU/ICU critical care.)

RR: Risk ratio; HDU: High dependency unit; ICU: Intensive care unit.