Impacting delayed pediatric influenza vaccination: a randomized controlled trial of text message reminders.

BACKGROUND: Influenza vaccination coverage is low, especially among low-income populations. Most doses are generally administered early in the influenza season, yet sustained vaccination efforts are crucial for achieving optimal coverage. The impact of text message influenza vaccination reminders was recently demonstrated in a low-income population. Little is known about their effect on children with delayed influenza vaccination or the most effective message type.

PURPOSE: To determine the impact of educational plus interactive text message reminders on influenza vaccination of urban low-income children unvaccinated by late fall.

DESIGN: Randomized controlled trial.

SETTING/PARTICIPANTS: Parents of 5,462 children aged 6 months-17 years from four academically affiliated pediatric clinics who were unvaccinated by mid-November 2011.

INTERVENTION: Eligible parents were stratified by their child's age and pediatric clinic site and randomized using a 1:1:1 allocation to educational plus interactive text message reminders, educational-only text message reminders, or usual care. Using an immunization registry-linked text messaging system, parents of intervention children received up to seven weekly text message reminders. One of the messages sent to parents in the educational plus interactive text message arm allowed selection of more information about influenza and influenza vaccination.

MAIN OUTCOME MEASURES: Influenza vaccination by March 31, 2012. Data were collected and analyzed between 2012 and 2014.

RESULTS: Most children were publicly insured and Spanish speaking. Baseline demographics were similar between groups. More children of parents in the educational plus interactive text message arm were vaccinated (38.5%) versus those in the educational-only text message (35.3%; difference=3.3%, 95% CI=0.02%, 6.5%; relative risk ratio (RRR)=1.09, 95% CI=1.002, 1.19) and usual care (34.8%; difference=3.8%, 95% CI=0.6%, 7.0%; RRR=1.11, 95% CI=1.02-1.21) arms.

CONCLUSIONS: Text message reminders with embedded educational information and options for interactivity have a small positive effect on influenza vaccination of urban, low-income, minority children who remain unvaccinated by late fall.