If you have the coronavirus, how long before symptoms show up?

By Stephanie Pappas - Live Science Contributor 3 days ago

When would you know you have the virus?

The incubation period for a virus is the time between catching the virus and showing symptoms of disease. For the novel coronavirus SARS-CoV-2, health officials estimate an incubation period of between one and 14 days.Most people start showing symptoms about five days after becoming infected, according to the World Health Organization (WHO).

These estimates are based on what was observed in the early days of the virus outbreak in Wuhan, China, the Centers for Disease Control and Prevention (CDC) reported. The estimates are also informed by what is known about the better-studied and related viruses MERS-CoV and SARS-CoV. SARS-CoV caused an outbreak of severe respiratory disease in 2002, and MERS-CoV emerged in 2012. 

Still, this estimate may change as more information becomes available. Some reports suggest that the incubation period may be as long as 24 days, according to a recent review paper published in the journal JAMA.

It's not yet clear whether people infected with the new coronavirus are very contagious during the incubation period, though there have been reports of people transmitting the virus without showing symptoms. It is also unclear what proportion of people catch the virus but never develop any symptoms. Based on data from China, the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19) suggests that asymptomatic cases are rare. On the cruise ship the Diamond Princess, however, 392 of 705 cases were reported to be asymptomatic, the CDC reported. People who are reported as asymptomatic may later go on to develop symptoms, however.

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