Utility of the ESSENCE Surveillance System in Monitoring the H1N1 Outbreak

Area of Science:

• Public Health
• Epidemiology
• Health Informatics

Background:

• The Electronic Surveillance System for the Early Notification of Community-Based Epidemics (ESSENCE) is utilized by public health departments in the National Capital Region (NCR).
• A cross-jurisdictional data sharing agreement has facilitated cooperative health information exchange in the NCR since 2004.
• ESSENCE enables the detection and monitoring of public health indicators.

Purpose of the Study:

• To compare emergency department visits for influenza-like illness (ILI) in the NCR between 2008 and 2009.
• To evaluate the utility of ESSENCE in monitoring community-based outbreaks and informing public health responses.
• To assess the impact of ESSENCE on understanding the magnitude and characteristics of ILI outbreaks.

Main Methods:

• Comparison of emergency department visit data for ILI in the NCR from 2008 and 2009.
• Analysis of rates, timing, and demographic composition of ILI visits.
• Utilizing syndrome-based surveillance data from ESSENCE.

Main Results:

• Significant differences were observed in the rates, timing, and demographic composition of ILI visits between 2008 and 2009.
• Monitoring through the regional ESSENCE system enhanced the understanding of ILI outbreak characteristics.
• The system provided critical community-level information for managing the 2009 H1N1 influenza outbreak.

Conclusions:

• Automated surveillance systems like ESSENCE are valuable for monitoring community-based outbreaks.
• ESSENCE improved the ability of public health practitioners to respond to public health emergencies.
• Syndrome-based surveillance has limitations, including reliance on chief complaints and potential influence of public behavior.