Text message reminders for second dose of influenza vaccine: a randomized controlled trial.

OBJECTIVE To determine whether provision of vaccine-health-literacy-promoting information in text message vaccine reminders improves receipt and timeliness of the second dose of influenza vaccine within a season for children in need of 2 doses. METHODS During the 2012-2013 season, families of eligible 6-month through 8-year-old children were recruited at the time of their first influenza vaccination from 3 community clinics in New York City. Children (n = 660) were randomly assigned to "educational" text message, "conventional" text message, and "written reminder-only" arms. At enrollment, all arms received a written reminder with next dose due date. Conventional messages included second dose due date and clinic walk-in hours. Educational messages added information regarding the need for a timely second dose. Receipt of second dose by April 30 was assessed by using χ(2) tests. Timeliness was assessed by receipt of second dose by 2 weeks after due date (day 42) using χ(2) and over time using a Kaplan-Meier analysis. RESULTS Most families were Latino and publicly insured with no significant between-arm differences between groups. Children in the educational arm were more likely to receive a second dose by April 30 (72.7%) versus conventional (66.7%) versus written reminder-only arm (57.1%; P = .003). They also had more timely receipt by day 42 (P < .001) and over time (P < .001). CONCLUSIONS In this low-income, urban, minority population, embedding health literacy information improved the effectiveness of text message reminders in promoting timely delivery of a second dose of influenza vaccine, compared with conventional text messages and written reminder only.