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Flu Surveillance in N.C.

Influenza surveillance in North Carolina is performed by the N.C. Influenza Sentinel Surveillance Program, part of a national network of healthcare providers and public health agencies tracking the rise, fall and virus strains of flu cases each year. By watching for outbreaks of flu and testing for different strains of flu, public health agencies can help prepare for and control outbreaks, determine appropriate treatments, assess the usefulness of antiviral drugs, and evaluate the effectiveness of vaccines.

Each week, sentinel physicians, university health centers, hospitals/medical centers and public health agencies across the state report "influenza-like illness" (ILI) to the national Centers for Disease Control and Prevention (CDC) and collect samples for virus strain identification. The reports include the total number of patient visits to each ILINet provider for that week and the number of those patients with ILI, broken down into five age groups. For purposes of this surveillance program, ILI is defined as fever of 100 degrees Fahrenheit or higher along with a cough or sore throat.

The ILINet program allows for timely identification of circulating influenza virus strains and can help detect new strains with pandemic potential. The emergence of 2009 H1N1 was first detected through this system long before illness was widespread in the U.S., allowing more time for vaccine development and implementation of other pandemic control measures. The samples collected through the ILINet system also help determine whether circulating strains are well-matched to the vaccine and whether they are resistant to any antiviral drugs.

North Carolina's Communicable Disease Control Branch and the State Laboratory of Public Health have continuously participated in the U.S. Influenza Sentinel Physicians Surveillance Network since the 2000-2001 flu season. For comparable national data, see the CDC weekly reports. North Carolina flu and pneumonia mortality data is published in the N.C. Detailed Mortality Statistics annual report (see ICD 10 codes J10-J18) on the State Center for Health Statistics web site.

Facts & Figures - Current Season

The North Carolina Influenza Sentinel Surveillance Program provides weekly updates throughout the influenza season (October-May) for influenza-like illnesses reported by N.C. hospital emergency departments (ED) and outpatient clinics (Sentinel sites) and for influenza virus isolates identified by the State Laboratory of Public Health. The official start of the 2019-20 influenza season was September 29, 2019.

Facts & Figures - Past Seasons

Data on flu-associated deaths (pediatric and adult) is included beginning with 2009-2010.