 Four strategically selected medical centers across the US representing the West Coast, Southwest, Midwest; and East Coast will enroll adult subjects presenting to the ED with an acute respiratory illness who fulfill CDC recommended criteria for receiving antiviral therapy. At each of the 4 sites, dedicated research coordinators will approach all adult age 18 years old ED patients with broadly defined respiratory related complaints and screen for those who meet CDC recommended criteria for antiviral therapy i.e. those at high-risk for complications or those with potential influenza-related complications. 