Table 7.

Uses of public health surveillance.

Categories (adapted from the World Bank) [98]	Examples of uses
(1) Early warning: serves as an early warning system to identify new emerging health problems	(i) Recognize cases or clusters of cases to trigger interventions to prevent transmission or reduce morbidity and mortality [98]. (ii) Serve as an early warning system to identify public health emergencies [79]. (iii) Detect epidemics [36, 99].
(2) Impact assessment: assesses public health impacts and trends of new emerging health problems	(i) Assess the public health impact of health events or determine and measure trends [98]. (ii) Estimate magnitude of a health problem [36, 99]. (iii) Document the distribution and spread of a health event [36, 99]. (iv) Portray the natural history of a disease [36, 99]. (v) Understand the economic and health impacts of a public health issue, and the nature and extent to which it disrupts communities [77].
(3) Intervention development and implementation: develops public health interventions and strategies and allocates public health resources	(i) Demonstrate the need for public health intervention programs and resources, and allocate resources during public health planning [98]. (ii) Lead to immediate public health action [75]. (iii) Set priorities and guide public health policy and strategies [79]. (iv) Rapidly communicate information among public health officials and health care workers so they can take appropriate actions to resolve problems [77]. (v) Appropriate and allocate prevention and care resources [36]. (vi) Make informed decisions related to resource allocation [77].
(4) Intervention evaluation: evaluates public health interventions and strategies	(i) Monitor effectiveness of prevention and control measures and intervention strategies [98]. (ii) Evaluate control and prevention measures [36, 99]. (iii) Evaluate programs, policies, and control measures [77]. (iv) Monitor isolation activities [36, 99]. (v) Detect changes in health practice [36]. (vi) Document impact of an intervention or progress towards specified public health targets/goals [79].
(5) Risk assessment: identifies risk factors and high risk populations	(i) Identify high-risk population groups or geographic areas to target interventions and guide analytic studies [98]. (ii) Monitor changes in infectious agents [36, 99]. (iii) Understand the factors that cause health events, both at the individual and community level [77]. (iv) Monitor and clarify the epidemiology of health problems [80]. (v) Reduce the risk of the occurrence of public health crises [77].
(6) Research: supports public health research	(i) Develop hypotheses that lead to analytic studies about risk factors for disease causation, propagation, or progression [98]. (ii) Formulating research hypotheses [75]. (iii) Generate and test hypotheses [36, 99]. (iv) Identify priorities and hypotheses for research [77]. (v) Facilitate epidemiologic and laboratory research [36].