EWAR stands for Early Warning, Alert and Response. EWAR is a system that provides an early warning of acute public health events and then connects this function to an immediate public health response. It is one of the most immediate and important functions of a surveillance system.

EWAR encompasses the following components and processes.

Emergencies also produce many risk factors that promote the emergence, transmission and outbreaks of communicable diseases, such as: food insecurity and progressive loss of livelihoods; disruption or breakdown of preventative or curative health and other essential services (e.g., access to safe water, sanitation); mass displacement of people into regimented or camp-like settlements or neighbouring 3Prior to EWAR implementation 1. Introduction to EWAR host communities, increasing the risk of overcrowding; sudden loss of livelihoods; and/or rapid environmental change due to a natural disaster (14–16). At the same time, national surveillance systems may be underperforming, disrupted or nonexistent during emergencies, which may adversely impact and delay the detection of and response to outbreaks (17, 18).

These factors can lead to excess morbidity and mortality due to outbreaks, or result in large-scale increases in disease transmission among emergency-affected populations. One of the most urgent priorities in an emergency is, therefore, to establish a functioning EWAR to rapidly detect and respond to events that may lead to outbreaks and other public health emergencies.