What do you mean by untraceable coincidence?

I have never been to a place where a confirmed case of COVID-19 epidemic or an asymptomatic infected person has been.

The coincidence of epidemic activities refers to the places where confirmed cases or asymptomatic infected people have been in COVID-19, and the non-coincidence means that they have never been to these places.

People who have been exposed to the environment and articles contaminated by the case or asymptomatic infected people are close contacts. Not being in close contact with a confirmed case or asymptomatic infected person at the same place at different times is not considered.