Table 2. Definitions of all independent variables and covariates. All variables were categorical and retrieved from University of California, Los Angeles's Clarity database with the exception of influenza incidence, which is continuous and retrieved from the Los Angeles County Department of Public Health.

Independent variables	Details
Intervention period	Preintervention (2013–2016), reflex testing (2016–2017), and noninterruptive CDS (2017–2019)
Covariates	Details
Provider	Provider ID number
Time	Month to year of the ordering date
Season	Month of the ordering date
Clinical setting	Inpatient, ED, and ambulatory
Severe illness or cardiorespiratory compromise	Binary; at least 1 ICD-10 code among a list of various child concepts of parents R57 (shock), R65 (SIRS/sepsis), I46 (cardiac arrest), I50 (heart failure), J96 (respiratory failure), P27–29 (respiratory/cardiovascular conditions of the newborn)
Immunocompromised state	Binary; at least 1 ICD-10 code among: B20 (HIV), D80–84 (immunodeficiency), Z94 (transplant organ status)
Influenza-like illness or viral upper respiratory infection	Binary; at least 1 ICD-10 code among: J06.9 (acute upper respiratory infection), J9–11 (influenza), J20–22 (bronchiolitis/unspecified acute lower respiratory infection)
Influenza incidence	Percent of positive influenza PCR tests at sentinel laboratories that report to Los Angeles County

Abbreviations: CDS, clinical decision support; ED, emergency department; ICD, international Classification of Disease; PCR, polymerase chain reaction.