Their findings firm up estimates of the virus’s incubation period before signs of fever, coughing and respiratory distress appear, offering support for current public-health control measures that recommend a 14-day monitoring and quarantine period for people who have been exposed to infection. Some state health agencies are recommending people isolate themselves for that period after returning from any international travel.

“We have a lot of confidence that the incubation period is around five days,” said Justin Lessler, an epidemiologist at the Johns Hopkins University Bloomberg School of Public Health who led the team that analyzed the progression of the disease in 181 cases…

Isolating people who may have been exposed to an infectious disease can limit an epidemic in the early stages of an outbreak, but only if public-health officials are confident they know how long it takes for people to show symptoms once they have been exposed. People are thought to be most contagious when they become symptomatic because the virus is typically spread when someone coughs or sneezes, according to the U.S. Centers for Disease Control and Prevention.