Effect of the frequency of delivery of reminders and an influenza tool kit on increasing influenza vaccination rates among adults with high-risk conditions.

Objective: To evaluate the incremental effect of a second client reminder postcard or an influenza tool kit targeted toward employers on increasing influenza vaccination rates among adults age < 65 years at high risk for complications from influenza illness.

Methods: In this demonstration study, enrollees of 3 managed care organizations (n = 8881) were randomized at the employer level into 4 arms: 1 postcard, 2 postcards, 1 postcard + tool kit, and 2 postcards + tool kit. The postcards and tool kits were mailed during the fall of 2001, and their effect on influenza vaccination rates was assessed through a survey.