There are four clinical types according to Chinese guideline on COVIF-19 pneumonia:

• Mild type: Clinical symptoms are mild and no signs of pneumonia are seen on imaging
• Common type: Fever, respiratory infections, and other symptoms; pneumonia can be seen on imaging.
• Severe type: Any of the following conditions:

1. Respiratory distress, RR > 30 times/min
2. Resting-state oxygen saturation < 93%
3. Arterial oxygen partial pressure (PaO2)/oxygen concentration (FiO2) < 300 mmHg

• Critical type: Any of the following conditions:

1. Respiratory failure occurs and requires mechanical ventilation
2. Patient suffers from shock
3. Combined with other organ failure requiring ICU monitoring and treatment