Objectives: We evaluated the impact of influenza vaccine text message reminders in a low-income obstetric population.
Methods: We conducted a randomized controlled trial that enrolled 1187 obstetric patients from 5 community-based clinics in New York City. The intervention group received 5 weekly text messages regarding influenza vaccination starting mid-September 2011 and 2 text message appointment reminders. Both groups received standard automated telephone appointment reminders. The prespecified endpoints were receipt of either pre- or postpartum influenza vaccination calculated cumulatively at the end of each month (September-December 2011).
Results: After adjusting for gestational age and number of clinic visits, women who received the intervention were 30% more likely to be vaccinated as of December 2011 (adjusted odds ratio [AOR] = 1.30; 95% confidence interval [CI] = 1.003, 1.69 end of September: AOR = 1.34; 95% CI = 0.98, 1.85; October: AOR = 1.35; 95% CI = 1.05, 1.75; November: AOR = 1.27; 95% CI = 0.98, 1.65). The subgroup of women early in the third trimester at randomization showed the greatest intervention effect (December 31: 61.9% intervention vs 49.0% control; AOR = 1.88; 95% CI = 1.12, 3.15).
Conclusions: In this low-income obstetric population, text messaging was associated with increased influenza vaccination, especially in those who received messages early in their third trimester.
Trial registration: ClinicalTrials.gov NCT01146912.