COVID-19 (summary)

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 Organization (WHO) declared pandemic. As of January 2021, over 90 million people had been infected globally with over 1.9 million deaths .

Clinical presentation

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

• fever (85-90%)
• cough (65-70%) with sputum in 30-35%
• smell and taste disturbances (50%)
• 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:

• acute respiratory distress syndrome (ARDS)
• coagulopathy: including PE and DIC
• secondary infections, e.g. bacterial pneumonia
• sepsis
• acute kidney injury (AKI)
• multiorgan failure
• secondary hemophagocytic lymphohistiocytosis

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 now primarily interhuman. The closest animal coronavirus by genetic sequence is a bat coronavirus . The cause of death is usually respiratory failure secondary to massive alveolar injury.

Radiographic features

The primary findings of COVID-19 are those of atypical or organizing pneumonia . Up to 18% of cases demonstrate normal chest x-rays or CT when mild/early in the disease course . 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 
• pleural effusion is rare

CT

The primary findings on CT in adults have been reported as :

• ground-glass opacities (GGO)
• crazy paving appearance (GGOs with inter-/intra-lobular septal thickening)
• air space consolidation
• bronchovascular thickening in the lesion
• traction bronchiectasis

Treatment and prognosis

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

An mRNA-based vaccine recently received regulatory approval in several territories .

The mortality rate is estimated to be 3.6% .

Differential diagnoses

• influenza or parainfluenza virus and other causes of atypical pneumonia 
• interstitial lung disease (ILD)
• pulmonary edema