Are people contagious earlier than they develop signs?

There is evidence that the novel coronavirus can be spread before an individual develops symptoms. This poses a problem because people who do not know they are infected may continue to go to work, school, and other public places. People who are sick and have symptoms are more likely to stay home, which means fewer opportunities for the virus to spread from one person to another. When asymptomatic transmission occurs, infection control experts and public health officials may need to take additional measures, such as social distancing, isolating patients, or using quarantines.