Achieving optimal immunization levels in school-age children.

In a school-based immunization program in four states, 70% of the students were fully immunized by the end of the first year and 85% by the end of the second year. Because of student turnover, 20% of the immunization levels achieved by the end of a school year were not sustained into the subsequent year. Levels reported by the state immunization officers were higher than those recorded by school personnel. Completed immunization series for students requiring immunizations were 33% to 40% higher for students enrolled at the start of the year than for students who entered during the school year. Students who were unimmunized at the beginning of the year had a better change (P less than 0.001) of being immunized by the end of the year than those whose immunization status was unknown. To maintain high levels, a program must be sustained and continuing, provide immunizations, and have careful administrative monitoring of child-specific population-based data. Schools are uniquely able to provide all of these elements, which can augment the efforts of private practitioners.