Classification of COVID-19 pneumonia

  • Mild: more black than white
  • Moderate: black = white
  • Severe: more white than black

Classification of severity

Severity of lung shadowing on a chest X-ray can be classified by comparing the area of abnormal lung (white) with the area of normal lung (black). If there is more black than white then shadowing is classified as 'Mild'. If there is approximately equal white and black then shadowing is classified as 'Moderate'. If there is more white than black then shadowing is classified as 'Severe'.

Mild shadowing

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Clinical information

  • 80-year-old male
  • Several days of cough and fever
  • Worsening shortness of breath
  • Family member recently died of COVID-19
  • COVID-19 swab positive 1 day after this chest X-ray

Mild shadowing

  • Shadowing of the mid and lower zones is patchy and partly peripheral
  • The majority of the lungs appear clear (more black than white)
  • Classification: Mild

Moderate shadowing

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Clinical information

  • 70-year-old male
  • 'Flu-like' symptoms for 10 days
  • Short of breath
  • O2 saturation of 85% on air
  • Crackles in left lung
  • COVID-19 swab positive 5 days after this chest X-ray (2 negative swabs)

Moderate shadowing

  • Shadowing is in a typical distribution - bilateral, peripheral, mid and lower zones
  • Approximately 50% of the lungs are affected (equal black and white)
  • Classification: Moderate

Severe shadowing

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Clinical information

  • 90-year-old male
  • History of heart disease with implantable cardioverter defibrillator (ICD)
  • Cough and fever
  • Crackles and reduced air entry
  • COVID-19 swab positive 2 days after this chest X-ray and died that day

Severe shadowing

  • Patchy shadowing is seen throughout both lungs
  • Shadowing is not as dense as in the previous example but there is less normal lung remaining
  • Shadowing is classified as severe - more than 50% of the lungs are affected (more white than black)
  • Classification: Severe

Severity of shadowing v clinical outcome

Although severity of shadowing is likely to be a helpful marker of overall clinical severity, it is not an accurate predictor of clinical outcome. Patients with severe shadowing can make a full clinical and radiological recovery - see patient journey 2. Patients with mild shadowing can die rapidly - see below.

Mild shadowing - poor outcome

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Clinical information

  • 80-year-old male
  • Ex-smoker with COPD
  • Cough worse for last few days
  • Not coping with 'rescue medication'
  • No fever
  • O2 saturation of 89% on air
  • COVID-19 swab positive 2 days after this chest X-ray and died the following day

Mild shadowing - poor outcome

  • Patchy shadowing is only seen in the right lower zone
  • Classification: Mild

Page author: Salisbury NHS Foundation Trust UK (Read bio)

Last reviewed: June 2020