child could enter school, which every state did. Federal authorities supported the new requirements with increases in state resources through CDC's Immunization Program, Medicaid, Maternal and Child Health funds, and community health centers to ensure the availability of providers who were willing to complete each child's immunizations prior to school entry.

Strategies for comprehensive immunization coverage for preschool children have proved more elusive. Among these children, there is no universal experience equivalent to school entry, and the United States lacks the centrally managed health care system that allows the United Kingdom to exert a strong influence over local providers. Nevertheless, the committee sees ensuring the proper immunization of preschool children as an explicit public health responsibility.

In principle, the public health system in the United States—constituted of the many separate federal, state, and local public health authorities—should protect everyone. As the immunization problem demonstrates, this system has gaps that need to be closed. Clear and effective leadership is required to find and close those gaps and to recognize and respond to those that may develop in the future. Private providers must play a greater role in meeting the need for immunization services in all settings, including low-income urban areas. Enhanced cooperation between the public health system and private providers will be needed to achieve this important shift in provider roles.

The Constitutional authority to act to protect the public's health and safety rests with the states (Freeman et al., 1993). ¹ The IOM (1988) has described the mission of public health as assuring conditions in which people can be healthy. Many states delegate some of their authority to local health departments. This does not mean that either state or local public health authorities must provide all services. Depending on the nature and extent of the available private resources, public resources may be needed only to guide public health planning, fill gaps in service, and ensure accountability.

The committee believes that it is essential that states understand their unique legal and organizational roles in public health in general and immunization in particular. Given the current level of attention and federal support, the committee feels that this may be a defining moment for immunization and child health, and states need to be prepared to lead effective programs. When the