Text4Health: Effectiveness of Immunization Registry-Linked Text Message Reminders On Adolescent Immunization Coverage

Background: Traditional immunization reminder-recall mechanisms have had limited effectiveness in adolescents and among economically disadvantaged populations. Text message reminder-recalls are a novel approach to remind patients and parents about immunizations.

Objectives: To determine the effectiveness of text message reminder-recalls for adolescent immunizations.

Methods: We conducted a randomized intervention with urban adolescents (n= 195) and age and gender matched controls (n=166) in need of meningococcal (MCV4) or tetanus, diphtheria, acellular pertussis (Tdap) vaccination.  Utilizing an immunization registry-linked text messaging platform, parents of intervention adolescents received a series of personalized text message immunization reminders. Primary outcomes were receipt of MCV4 or Tdap at 4, 12 and 24 weeks post randomization. Coverage rates were compared using chi square. Logistic regression was used to assess the impact of age, gender, race/ethnicity, insurance, and language on the intervention. Finally, we conducted cost-benefit analyses for sustaining the intervention for 2 years in a cohort of 100,000 adolescents.

Results: Families were primarily Latino (58%) and had Medicaid (75%). Using intention to treat analyses, there was a 10.7% (95% CI 4.8-16.5%) point difference in receipt of MCV4/Tdap vaccine at 4 weeks between intervention adolescents and controls (14.9 vs. 4.2%; p< .01). At 12 weeks, there was a 12.3% (95% CI 4.4- 20.4%) point difference (25.6% vs. 13.3%; p<.01). At 24 weeks, a 17.9% (95% CI 9.1%- 26.8%) point difference (35.4 vs. 17.5%; p<.001). Sociodemographic variables did not significantly affect our findings. If the intervention were sustained for a two-year period, estimated costs would be $0.42 per additional vaccine delivered.

Conclusions: Immunization registry-linked text messaging appears to be an effective mechanism to deliver reminders in an urban, adolescent population. Moreover, our analyses suggest that improvements in immunization coverage can be achieved for larger populations with little additional cost. Funded by HRSA:R40MC08961