Age-appropriate immunization laws: A randomized trial of information dissemination

Objective. North Carolina has civil laws requiring immunization for school and day care entry. However, these laws do little to promote immunization at the ages for which most vaccines are actually recommended. To address this issue, the state of North Carolina has specific statutes which require age-appropriate immunization. We sought to determine if parental knowledge of this law would impact on age-appropriate immunization rates. Setting. North Carolina. Methods. Parents of a birth cohort of 1399 children were enrolled. Subjects were randomized to one of three groups: (1) control group (received no mailings); (2) health message group; and (3) law message group. Letters were mailed to parents in the intervention groups prior to the time of their 2-month well-child visit. Subsequently, each intervention group received postcard reminders of the immunization schedule in advance of the 4- and 6-month well-child visits. Parents were then asked to name all sites of immunization delivery. Provider offices were contacted to obtain immunization histories. Results. Overall response rate was 51%. There were no significant differences in immunization rates among the three groups. Immunization rates for subjects who reported being covered by Medicaid were lower for this group as a whole, but there were no significant differences between the Medicaid recipients in the intervention and control groups. Conclusions. Reminders with or without a message about age-appropriate immunization laws did not result in increased immunization rates. Based on these data, we do not recommend the institution of a reminder-based educational campaign to inform parents of the law, especially if no means of enforcement are included in the program. However, age-appropriate laws are valuable in that they make a clear statement of the importance of immunizations to protect the public's health.