Surveillance is not the only process that can provide information to inform public health action. The results of research can also inform public health action. Sometimes the distinction between surveillance, particularly surveillance of (or for) emerging infections, and research can be difficult to define. This can have important implications, particularly where different ethical, legal (usually data protection) and funding rules apply to research compared to surveillance. As a general rule, the key distinction is that surveillance should always be justified by, and seen as an integral component of, ongoing established prevention and control programmes.

 There are a number of other dimensions on which research and surveillance can be compared, as outlined table 1. Although the distinction between research and surveillance is not always clear-cut for some of the criteria proposed in the table, and sometimes research or surveillance will not fit with all of the criteria suggested, this provides a framework for assessing whether a problem should be addressed through surveillance or research. 

Research

Surveillance

Creates new knowledge (about what works and what doesn't)

May contribute to knowledge (understanding) but is primarily about measuring what is already known

Is based on a hypothesis

Not usually based on a specific hypothesis (other than that the frequency or distribution of that which is the subject of surveillance may change)

May involve experiments, new interventions or purposive allocation of subjects to different interventions

Never involves experiments or purposive allocation of subjects to different interventions

Is based on a scientifically valid sample size (although this may not apply to pilot studies)

Rarely based on a scientifically defined sample size

Extensive statistical analysis of data is routine

Statistical analysis usually limited to simple measures of trend or distribution

Results are generalisable and hence publishable

Results may be generalisable

Responsibility to act on findings is not necessarily clear

Responsibility to act should always be clear

Findings may result in the application of new clinical or public health practice

Findings may result in application of established clinical or public health practice