contact tracing
A method of keeping tract of the contacts a person with an infectious disease has, to prevent the spread of the disease. Tracing can be used to find the original source of the disease by looking at one's contacts before they were infected, and after they were infected to see who they may have spread the disease to. Once individuals who had contacts with the disease have been identified they are tested for the disease, to stop them from disease spreading behavior till their condition has been identified. If individuals are found to be infected with the disease they continue to stop any disease spreading behavior, (e.g. isolation) and are treated, so they don't spread the disease to others.
People in charge of public health and the spreading of VD, have being using contact tracing long before those fighting the lasted pandemic used it.
Contact tracing
Contact tracing - an extension of big mother's tracking device for kids
Villanelle carried with her a piece of chalk for contact tracing