Why is surveillance data important and how can it help us? Surveillance data which is analyzed and disseminated on a regular and ongoing basis helps us know when and how to take public health action in a number of ways:

- first, it helps us detect and control outbreaks of disease. For example, each year, surveillance data concerning influenza activity is disseminated to health care providers and used to determine when intensified vaccination efforts and chemo-prophylaxis should be directed to persons within the population at high risk for complications.

- Analysis of surveillance data also helps us determine the etiology and natural epidemiological history of diseases, environmental and occupational exposures, and health behaviors, and increases and decreases in their occurrence over time.

- Surveillance data is useful for monitoring changes in health practices and behaviors. Information concerning life-style habits is especially important for chronic diseases where trends in risk behavior(s) often precede changes in health outcomes. This type of information is necessary for helping us determine how to change the provision of health care services as life-style habits change over time.

- Surveillance data also helps us evaluate the effectiveness of disease prevention, control, and treatment programs and policies at reaching at-risk populations, and informs individuals and organizations responsible for the development of these programs of the need for changes and refinements. For example, during the mid-1980’s, the incidence of measles within the United States began to increase as a result of outbreaks occurring within school-aged and inner-city preschool populations. These findings lead to the adoption of a policy to require two, rather than just one, dose of measles, mumps, and rubella vaccine for all children prior to school entry, and to targeted efforts to have private and public vaccination providers improve on-time vaccination rates among pre-school children.

And it’s important to remember that surveillance data can help us determine the most appropriate and efficient allocation of resources and personnel, which in turn, helps us establish good public health policies.