Public health in managed care: a randomized controlled trial of the effectiveness of postcard reminders.

OBJECTIVES: This study evaluated the effectiveness of an annual public health intervention in a managed care setting. METHODS: Managed care organization members 65 years and older who received influenza immunization in 1996 were randomized to an intervention group (mailed a postcard reminder to receive an influenza vaccination in 1997) or a control group (no postcard). Vaccination rates for both groups were assessed monthly. RESULTS: Members receiving the intervention were no more likely to be immunized (78.6%) than members of the control group (77.2%, P = .222). Members were vaccinated at the same pace regardless of vaccination history and postcard intervention status. CONCLUSIONS: Postcard reminders were not an effective intervention among seniors who had been vaccinated the previous year.