• efforts to improve and sustain high vaccine coverage levels, and

• immunization finance policies and practices.

This chapter examines in turn the scope and evidentiary base of three of these roles: infectious disease prevention and control, surveillance of vaccine coverage and safety, and efforts to improve and sustain high vaccine coverage levels. The final role—immunization finance policies and practices—is reviewed in Chapter 5. The three roles discussed in this chapter complement the vaccine purchase and delivery arrangements discussed in Chapter 3, and are commonly regarded as infrastructure efforts.

Infrastructure is defined as “an underlying base or foundation” and refers to “the basic facilities, equipment, and installations needed for the functioning of a system” (Webster’s Dictionary, 1996:569). In the context of this study, infrastructure encompasses the formal set of arrangements that guide the immunization system in the United States. Although we focus principally on the public infrastructure for immunization services at the federal and state levels, we recognize that these efforts interact with local health agencies, private health care providers, and private insurers in a complex manner. Most important, the presence or absence of private health care services, including insurance coverage and standard benefits that provide immunization services for children, adolescents, and adults at reasonable cost, influences the infrastructure burden that is located within the public health sector. The scope and quality of the assessment, educational, and technical assistance efforts required within the public sector to ensure access to recommended vaccines and monitor the performance of health care providers thus depends on the extent to which the private sector can be relied upon to serve the needs of vulnerable populations.

The importance of infrastructure is not always apparent. It is often difficult to grasp, for example, why high levels of immunization coverage cannot be achieved simply by the purchase and delivery of vaccines. But sustaining high levels of immunization coverage for an increasing number of vaccines for the 11,000 children born each day, as well as a growing immigrant population, requires various forms of data collection, identification and analysis of high-risk and under served populations, and technical assistance to health care providers. Certain roles and responsibilities within the public health sector acquire greater or lesser importance as health conditions shift and private providers acquire new responsibilities for immunization services. As immunization services are integrated into routine primary care, for example, the need for precise measurement and appropriate accountability standards grows, while actual caseloads decline within the public sector. Targeting outreach and reminder services to those most in need requires reliable benchmark, baseline, and