Incubation period

Christian Hoffmann Bernd Sebastian Kamps Published 20 January 2021

After an average incubation time of around 5 days (range: 2-14 days), a typical COVID-19 infection begins with dry cough and low-grade fever (38,1–39°C or 100,5–102,1°F), often accompanied by diminishment of smell and taste. In most patients, COVID-19 remains mild or moderate and symptoms resolve within a week and patients typically recover at home. Around 10% of patients remain symptomatic through the second week. The longer the symptoms persist, the higher the risk of developing more severe COVID-19, requiring hospitalization, intensive care and invasive ventilation. The outcome of COVID-19 is often unpredictable, especially in older patients with comorbidities. The clinical picture ranges from completely asymptomatic to rapidly devastating courses. In this chapter we discuss the clinical presentation, including • The incubation period • Asymptomatic patients • Frequent and rare symptoms • Laboratory findings • Outcome: Risk factors for severe disease

• Reactivations and reinfections

• Long-term sequelae The radiological findings are described in the diagnostic chapter, page 303.

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A pooled analysis of 181 confirmed COVID-19 cases with identifiable exposure and symptom onset windows estimated the median incubation period to be 5,1 days with a 95% CI of 4.5 to 5.8 days (Lauer 2020). The authors estimated that 97.5% of those who develop symptoms will do so within 11,5 days (8,2 to 15,6 days) of infection. Fewer than 2,5% of infected persons will show symptoms within 2,2 days, whereas symptom onset will occur within 11,5 days in 97,5%. However, these estimates imply that, under conservative assumptions, 101 out of every 10.000 cases will develop symptoms after 14 days of active