Table 1.

Influenza surveillance variables and the corresponding data definitions.

Surveillance variable (abbreviation)	Description	Definition
ILIa diagnosis codes [32] (TMUHcSb-ILI)	Patients who were diagnosed with ILI-related symptoms	ILI diagnosis codes: (1) ICD-9-CMc codes: 480.xx~487.xx.; (2) ICD-10-CM codesd: J09-~J18-, A22-, A37-, B25-, and B44-
Rapid influenza laboratory tests with positive results (TMUHcS-RITPe)	Patients who had positive results on rapid influenza tests based on ILI diagnosis codes	Rapid Influenza laboratory tests: positive, + And ILI diagnosis codes: (1) ICD-9-CM codes: 480.xx~487.xx (2) ICD-10-CM codesd: J09-~J18-, A22-, A37-, B25-, and B44-
Influenza medication use (TMUHcS-IMUf)	Patients who were prescribed with antiviral drugs against influenza based on ILI diagnosis codes	Medications: Tamiflu, Relenza, Rapiacta, and Avigan And ILI diagnosis codes: (1) ICD-9-CM codes: 480.xx-487.xx (2) ICD-10-CM codesd: J09- to J18-, A22-, A37-, B25-, and B44-

^aILI: influenza-like illness.

^bTMUHcS: Taipei Medical University Health Care System.

^cICD-9-CM: International Classification of Disease, Ninth Revision, Clinical Modification.

^dImplemented in Taiwan in January 2016.

^eRITP: rapid influenza laboratory tests with positive results.

^fIMU: influenza medication use.