COVID-19 (summary)

Last revised by Dr Daniel J Bell on 04 Oct 2021

This summary article is intended to be used as a quick reference guide. Please see our complete COVID-19 article for more detail. 

COVID-19 (coronavirus disease 2019) is a viral infectious disease caused by SARS-CoV-2 and is currently a World Health Organizatiοn (WHO) declared pandemic. As of October 2021, over 200 million people had been infected globally with over 4.5 million deaths 13.

Many people with SARS-CoV-2 infection are asymptomatic 9. Symptoms and signs of COVID-19 are non-specific 1 but in symptomatic individuals most commonly include:

  • fever (85-90%)
  • cough (65-70%) with sputum (30-35%)
  • smell and taste disturbances (50%) 12
  • fatigue (35-40%)
  • shortness of breath (15-20%)

The likelihood of severe illness requiring hospitalization correlates closely with male sex, advanced age and presence of comorbidities. 

  • ~5% admitted patients require ICU admission

Multiple serious sequelae have been reported including:

SARS-CoV-2 is a member of the Betacoronavirus genus, one of the genera of the Coronaviridae family of viruses. SARS-CoV-2 is indirectly zoonotic, but transmission is now primarily interhuman. The closest animal coronavirus by genetic sequence is a bat coronavirus 5. The cause of death is usually respiratory failure secondary to massive alveolar injury.

The primary findings of COVID-19 are those of an atypical or organizing pneumonia 2,3. Up to 18% of cases demonstrate normal chest x-rays or CT when mild/early in the disease course 10. Bilateral and/or multilobar involvement is common, more often with a lower zone distribution.

The primary findings on CT chest in adults are 2,3,16:

There are several therapeutic approaches: some of them inhibit the replication of the virus, others reduce the inflammatory response, whilst others inhibit coagulation 17,18.

Treatment is primarily supportive including mechanical ventilation for some patients. Dexamethasone has been shown to reduce mortality in ventilated patients or those on oxygen therapy 14.

Several highly-effective vaccines have now received regulatory approval in multiple territories: some of them use mRNA technology; others the technology of the adenoviral vector 15,20

The mortality rate is estimated to be 3.6% 10.

The persistence of disabling symptoms long after the acute illness has resolved has become known as long COVID 19.

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Cases and figures

  • Figure 1: SARS-CoV-2 (photo)
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  • Case 1
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  • Case 2
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  • Case 3
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  • Case 4: with rapidly progressive ARDS
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  • Case 5: COVID-19 pneumonia - pediatric
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  • Case 6
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  • Case 7
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  • Case 8
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  • Case 9
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  • Case 10
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  • Case 11
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  • Case 12
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  • Case 13
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  • Case 14
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  • Case 15
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  • Case 16
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  • Case 17
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  • Case 18
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  • Case 19
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