Figure 3.

Types of events that a multi-purpose syndromic surveillance service aims to detect.

Purpose	Objective	Event type
Comprehensive population surveillance	provide early-warning of unexpected threats to public health	epidemic of severe respiratory illness, e.g. SARS, COVID-19
		cryptosporidium outbreaks
		norovirus outbreaks
		food poisoning outbreaks
		bioterrorism
	monitor trends to give early warning of atypical activity	seasonal influenza
		seasonal respiratory syncytial virus
		scarlet fever
		“Back to school” asthma [1]
		measles
		mumps
		rubella
		pertussis
		hay fever
		insect bites
Targeted sub-group surveillance surveillance	Monitoring of specific context to provide reassurance or early warning of impact on health	vaccine impact
		volcanic ash cloud
		floods
		large industrial fires
Situational awareness	Measuring impact of known exposure	out of season pandemic influenza
		extreme cold weather
		heat waves
		“thunderstorm asthma” [2]
		impact of air pollution
		impact of water contamination