The median incubation period for COVID-19 is estimated to be 4-5 days, with an interquartile range of 2-7 days. Based on patients’ viral shedding patterns and on epidemiological modelling, patients appear to be infectious for 2-3 days prior to the onset of symptoms, and the contribution of pre-symptomatic infections to the overall pandemic may be substantial.

Based on early data, the basic reproductive number for the virus was approximately 2.2 (meaning that on average each person spread the infection to two others).

A male preponderance of cases has been noted globally both in terms of absolute case numbers, and in severe disease.

Risk factors for severe disease include older age, cardiopulmonary comorbidities and diabetes mellitus. Very few cases which required hospitalisation have been reported among children under the age of 15 years (~1%). To date there has been little reported on associations between patients with HIV or TB and COVID-19.

According to a study in The Lancet, patients with severe COVID-19 tend to have a high viral load and a long virus shedding period. This finding suggests that the viral load of SARS-CoV-2 might be a useful marker for assessing disease severity and prognosis.

Answers extracted from: Clinical management of suspected or confirmed COVID-19 disease (Version 4, May 2020)

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