Clinical presentation

Clinical presentation 

The incubation period of COVID-19 infection has been estimated to have a median of 5.1 days those who will develop symptoms doing so within 11 days of exposure.  This has informed the time interval of 14 days for quarantining of potentially exposed individuals (1).

 The ratio of asymptomatic to symptomatic infection is currently unknown, and there may be differences in the rates in children compared to adults.

Symptomatic COVID-19 infection usually presents as a respiratory syndrome, most commonly with fever and cough (2, 3).

Fever has been reported in up to 99% of people at some time during the course of their illness, but importantly has been reported to be present at the time of hospital presentation in only 44% of patients, and at some time during the hospital admission in 89% (4).

Other common symptoms are cough, dyspnoea, fatigue, anorexia, anosmia, myalgia and confusion.  Symptoms reported much less frequently (<5% of cases) include sore throat, rhinorrhoea, headache, chest pain, dizziness, abdominal pain, diarrhoea and nausea (2, 3).

Around 80% of COVID-19 infections present as a mild respiratory illness in a patient who is ambulatory and can generally be managed outside the hospital. Around 15% typically need hospital care (usually for moderate to severe pneumonia), and another 5% have critical illness requiring more intensive supports (5).

Of those who require hospitalization,  the median time to hospital admission is 7 days.

The median time to acute respiratory distress syndrome (ARDS) is 8 days (IQR 6-12) (2).

Approximately one quarter of patients who are hospitalized generally need transfer to the intensive care unit for the management of complications such as hypoxaemic (abnormally low concentration of oxygen in blood) respiratory failure or hypo-tension requiring vaso-pressor support (6).

Clinical features that have been identified more often in  COVID-infected patients who have had a fatal outcome compared to those who survive are: reports of difficulty in breathing, higher white blood cell count at presentation with a lower lymphocyte count (Lymphocytes include natural killer cells).

Low lymphocyte counts can occur after a cold or infection. 

High lymphocytes are an indicator that your body is deal