Influenza is not a reportable disease in New Hampshire, but surveillance systems are in place to help determine the extent of illness and current circulating virus types. During the traditional influenza season (beginning of October through mid-May), weekly flu reports are published. Data from heath care providers and laboratories, as well as data from other surveillance systems, are analyzed, and NH flu activity is reported weekly to the Centers for Disease Control and Prevention (CDC). New Hampshire participates in the US Influenza Sentinel Provider Surveillance System, a collaborative effort between the CDC, the NH Department of Health and Human Services, and health care providers throughout the State.