All infected cases of SARS-CoV-2 are initially asymptomatic. This means, that the virus is already in the organism, however there’s no way to tell it. There simply are no signs of virus, no symptoms. The time before catching the virus until the onset of symptoms is called incubation period which can last between 2 and 24 days based on the current observations.
However, some people catching the virus never fall sick. There’s an evidence of a woman being disease carrier, but apparently not suffering any symptoms of a disease. Asymptomatic cases, unfortunately, can transfer the disease to others, who will react with symptoms. This means that there’s a threat of healthy people catching the virus from other apparently healthy people.