The current evidence seems to support the fact that most people in the population who come into contact with the virus will have mild disease or will be asymptomatic especially if there are no underlying conditions. There have been cases of people testing positive for the virus without exactly having

1. A history of travel to an area with COVID-19 cases

2. Come into contact with someone having signs of the disease etc.

It is possible that community level infection will account for this. But is it also possible that the virus has been present all this while but had remained undetected because we did not know about them and hence had no test available to detect them?