This document specifies a reference architecture for event-based syndromic surveillance systems for infectious diseases. The system reference architecture addresses architectural components including concepts, data sources, and outputs of syndromic surveillance system.

From the perspective of the diagnostic process,^[11] this document covers the processes from the symptom-onset stage to the health-behaviour stage, which is prior to the healthcare-encounter stage.

Non-infectious health hazards, such as natural disasters, human-induced emergencies and chronic diseases, and their associated surveillance systems are beyond the scope of this document.