Credit card transaction logs were used to assess the consistency in the route of the patient identified through interview, and the scope of contacts was assessed by specifying the locations visited. However, if the patient did not use a credit card under their name or if another person used the patient’s card, the information may be misinterpreted. Thus, rechecking the contents of the credit card log was necessary, and instances of not being able to use the information at the appropriate time may occur.