The epidemiological context of a patient's presentation can provide important information for clinicians to aid in diagnosis and treatment. The investigators previously developed and validated a syndromic surveillance tool for detecting influenza-like illness (ILI) encounters. The investigators then evaluated 40,642 outpatient ILI episodes during 'flu seasons' over 6 years. The investigators found that even after controlling for patient presentation and physician factors, the context in which a patient presented was strongly associated with the likelihood that an antimicrobial agent would be prescribed. Specifically, patients were less likely to be prescribed an antibiotic if they presented with ILI during the pandemic influenza period (when awareness of 'flu season' was very high), or after their physician had personally seen many patients with ILI in the prior week.