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COVID-19: Clinical characteristics


The majority of people with COVID-19 have uncomplicated or mild illness (81%), with non-specific symptoms.

A relatively small proportion of people, particularly but by no means exclusively in those aged >70 years, will develop severe illness requiring oxygen therapy (14%) and approximately 5% will require intensive care unit treatment. Time from the onset of the infection to hospitalisation can be up to ~13 days. Of those critically ill, most will require mechanical ventilation. 

The most common diagnosis in severe COVID-19 patients is severe pneumonia; this can progress to acute respiratory distress syndrome, and life-threatening multi-organ dysfunction and death.

Mortality has been estimated at between 1 and 2% of those infected, the higher figure in men.


COVID-19 disease severity
Mild disease: Symptomatic patients meeting the case definition for COVID-19 without evidence of viral pneumonia or hypoxia
Moderate disease: Pneumonia
Severe disease: Severe pneumonia
Critical disease: Acute respiratory distress syndrome (ARDS), sepsis, septic shock

Other complications that have been described in COVID-19 patients include acute, life-threatening conditions such as: acute pulmonary embolism, acute coronary syndrome, acute stroke and delirium.

Of those infected, increased severity of illness can be seen more commonly in people aged 65 years and older, those living in a nursing home or long-term care facility, and in people with underlying medical conditions such as hypertension, chronic lung disease, moderate to severe asthma, cardiac disease, immunocompromised states (i.e., cancer, smoking, HIV or AIDS, steroids), BMI > 40, diabetes, chronic kidney disease, and liver disease.