1.4 Important concepts in surveillance
In addition to the above terms, public health surveillance includes a series of concepts. It is important to understand how these concepts are interpreted when talking about surveillance.
Capture and reporting frequency of event data
Surveillance captures data on an ‘ongoing’ basis. In doing so, surveillance doesn’t always intend to capture all such events of the disease of interest. Rather, surveillance attempts to consistently capture a similar proportion of events over time and to report these data in a regular way. The frequency of reporting of these data is linked to the public health question being asked. Rapid reporting of surveillance data is crucial in high-hazard situations, for example, when dealing with a highly infectious and rapidly spreading
Source of health information
The sources of health information that surveillance can use are varied. Surveillance systems can collect data directly from persons (or animals) in a population, from laboratory samples, clinical diagnosis of a disease based on symptomology made by clinicians in a hospital or veterinarians in a veterinary clinic, or from a population census – making use of data captured for a non-public health purpose. The type of data collected depends on the purpose of surveillance.
Link to prevention and control of infection
Carrying out public health surveillance is justified by the link between the gathering of information and the performance of interventions that prevent and/or control a health event, such as disease. Good surveillance activities are linked to effective response interventions. Surveillance data are also important in guiding research activities, which might guide new public health interventions in the future.
1.3 Key surveillance terms
