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 2024, ~775 million people had been infected globally with over 7 million deaths 13.
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Clinical presentation
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%)
fatigue (35-40%)
shortness of breath (15-20%)
Complications
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:
secondary infections, e.g. bacterial pneumonia
myocardial injury
Pathology
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 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.
Radiographic features
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.
Plain radiograph
patchy or diffuse airspace opacities, whether consolidation or ground-glass opacity 10,11
pleural effusion is rare 11
CT
The primary findings on CT chest in adults are 2,3,16:
crazy paving appearance (GGOs with septal thickening)
bronchovascular thickening in the lesion
Treatment and prognosis
There are several therapeutic approaches: some of them inhibit the replication of the virus, others reduce the inflammatory response (e.g. interleukin inhibitors), whilst others inhibit coagulation 17,18,22.
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.
The use of acetaminophen - evaluated in 28 studies conducted in 13 different countries for a total of almost 550,000 patients treated - seems to correlate with a greater risk of serious consequences (28%) and a greater risk of death (24%) 23-25.
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 15,20,21.
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.
Differential diagnoses
influenza or parainfluenza virus and other causes of atypical pneumonia 7,8
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