Surveillance. Information for action.

Success in immunization requires success in developing an adequate information base. While special studies are important, there is no substitute for surveillance systems. Such systems help evaluate health impact, monitor trends in reported disease and adverse events, and identify areas for more intense investigation. Surveillance data alone have played major roles in immunization strategy changes. Successful surveillance relies on cooperation by health care providers and health departments. While filling out forms and reporting cases may be viewed as a burden by some, such information in the aggregate becomes an important part of the knowledge base used to refocus implementation efforts and potentially to change strategies. Reporting by all physicians is particularly important when reported cases lead to aggressive control actions such as outbreak control. Rapid reporting even when cases are not confirmed can help health departments ensure that needed laboratory specimens are collected and allow control measures to be undertaken before disease containment becomes difficult. In conclusion, any immunization program worth instituting is worth monitoring. Surveillance represents constant vigilance to ensure effective control or elimination of disease.