Causes of Low Preschool Immunization Coverage in the United States

In 1978, the United States established the objective of completing the basic immunization series of at least 90% of children by age two years by the year 1990. Although state school immunization laws have led to the immunization of over 95% of school enterers (32), the situation among preschoolers is less encouraging. Recent outbreak investigations in many inner city areas have estimated that only 40-60% of children have completed the series by age two years (12, 13, 55). This low coverage among preschoolers is reflected in the recent resurgence of measles (7, 11, 57). In 1990, the number of reported measles cases (provisional total 27, 672) was the highest since 1977 (55, 201 cases reported), compared with a nadir of 1497 cases in 1983. Approximately one half of reported cases in 1990 Were among preschool children; among vaccine-eligible preschoolers aged 16-59 months, 79% were unvaccinated (lOa). There is no mechanism similar to school immunization laws to achieve universal immunization of preschoolers. State day care immunization laws only affect licensed centers, which care for an estimated 20% of children