Text Message Reminders to Improve Infant Immunization in Guatemala: A Randomized Clinical Trial

Objective: Millions of infants worldwide remain under-immunized and at risk for unnecessary morbidity and mortality. Text messaging may offer a low-cost solution. We aimed to evaluate text message reminders to improve infant immunization in Guatemala.

Methods: A randomized clinical trial was conducted at four public health clinics in rural and urban Guatemala. Infants ages six weeks to six months presenting for the first visit of the primary immunization series were randomly and equally allocated to an intervention or usual care group. Intervention participants were sent three text reminders before the second and third vaccine visits. The main outcome was timeliness of the second and third visits of the primary immunization series.

Results: Of 1088 families approached for enrollment between March to November 2016, 871 were eligible and 720 (82.7%) participated; only 54 families did not own a cell phone. Due to country-wide vaccine shortages, visit completion was used as a proxy for overall immunization coverage. In intention to treat analysis, both intervention and usual care groups had high rates of visit completion, but intervention participants presented on the scheduled date more often (151 [42.2%] of 358 intervention vs. 111 [30.7%] of 362 usual care participants for visit 2, p = 0.001, and 112 [34.0%] of 329 intervention vs. 90 [27.0%] of 333 usual care participants for visit 3, p = 0.05). Intervention caregivers were significantly more likely to want to receive future text message reminders for vaccines and other appointments and were more willing to pay for these reminders.

Conclusion: Caregivers who were sent text message reminders in urban and rural Guatemala were less delayed for their child's immunization visits and reported high user satisfaction. Text message reminders may be an effective tool to increase infant vaccination coverage in low-income settings by reminding parents to vaccinate.

Trial Registration: NCT02567006 at clinicaltrials.gov.