Table 1.

Hospital-Based Clinical Staging System for COVID-19 to Assess Disease Severity

Stage	Clinical Presentation	Characteristic Features
Stage A	Asymptomatic	Patients with no signs or symptoms of infection
Stage B	Mild Infection	Upper respiratory tract infection symptoms and other mild symptoms (including fever and gastrointestinal symptoms) without evidence of pneumonia
Stage C	Moderate Infection	Patients with hypoxia with oxygen saturation less than 93% at rest or presence of pneumonia not requiring ICU admission
Stage D	Severe Infection	Pneumonia requiring ICU admission or any of the following: 1. Respiratory rate of 30 breaths/min 2. Arterial oxygen partial pressure to fractional inspiratory oxygen ratio (PaO2/FiO2) less than 300 3. More than 50% lung involvement on imaging within 24–48 hours 4. Critical respiratory failure requiring mechanical ventilation, septic shock, or multi-organ dysfunction