tracer

noun
trac*er \ ˈtrā-sər \
14th century{ds||1||}
  • one that traces, tracks down, or searches out: such as
  • a person who traces missing persons or property and especially goods lost in transit
  • an inquiry sent out in tracing a shipment lost in transit

contact tracing

noun
contact tracing \
1910
  • the practice of identifying, notifying, and monitoring individuals who may have had close contact with a person having a confirmed or probable case of an infectious disease as a means of controlling the spread of infection
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