Seasonal Influenza - Surveillance

Many people get sick with influenza (flu) every year in New Jersey (NJ) without ever seeing a doctor or reporting their illness. Therefore, the New Jersey Department of Health and Senior Services (NJDHSS) uses various indicators to determine how widespread the flu is in NJ, rather than tracking individual cases. The NJDHSS Public Health and Environmental Laboratories (NJPHEL) also tests influenza specimens to monitor which flu strains are circulating each season. The NJDHSS utilizes several surveillance systems to monitor influenza activity, which are described below.

Influenza Sentinel Provider Surveillance: NJDHSS, along with local health departments, enrolls physicians throughout the state to participate in this program. Physicians are asked to report on a weekly basis the number of patients seen in their practices and the number of patients that are seen with ILI by age category.

Influenza-like illness ( ILI ) surveillance: NJDHSS collects information once a week throughout the state on ILI from hospital emergency departments and long term care facilities and collects absenteeism information from schools. In addition to ILI data, NJDHSS also receives weekly reports on the number of respiratory syncytial virus (RSV) tests performed and the number that are positive from select hospitals. RSV is a respiratory infection with symptoms similar to influenza. Collecting information on positive RSV samples can help determine if another respiratory illness is influencing ILI reports.

Pediatric Influenza Surveillance: NJDHSS conducts surveillance for severe cases of pediatric influenza and death. This information is captured using a web-based form and analyzed for risk factors and complications related to influenza.

Weekly Reports: All of the above information is analyzed and a weekly ILI report is produced. NJDHSS also sends statewide influenza activity levels to the Centers for Disease Control and Prevention for inclusion in the weekly national influenza report.