Public health surveillance is the ongoing systematic collection, analysis and interpretation of outcome-specific health data, closely integrated with the timely dissemination of those data to those responsible for preventing and controlling disease or injury.

Public health surveillance systems should have the capacity to
- Collect and analyze data
- Disseminate data to public health programs, and
- Regularly evaluate the effectiveness of the use of the disseminated data.

Public health information systems, on the other hand, encompass a variety of data sources essential to public health. They may be used for surveillance, but they lack some critical elements of surveillance systems.