The effect of mHealth application on improving childhood immunization coverage and timeliness: a case of the Gurage Zone, SNNPR, Ethiopia, a randomized controlled trial

Ethiopia has achieved remarkable decreases in under-5, infant, and neonatal mortality and has reached the target of MDG four three years ahead of the deadline, but child and infant health issues continue to result in high rates of mortality and morbidity. Therefore, to improve child and infant health services and accelerate the achievement of the Sustainable Development Goals, it is imperative that an innovative and cost-effective strategy be developed. Previous studies have found that the implementation of digital health technology, particularly through mobile health technology, such as short message reminder systems, has enhanced vaccination coverage and increased the demand for routine vaccinations in children among low- and middle-income countries. However, there is a paucity of research on the effect of mHealth applications on improving routine childhood immunization coverage and timeliness in the Gurage Zone, SNNPR, Southwest Ethiopia. A randomized controlled trial with two arms and a parallel design was conducted with 408 mother-infant pairs. Using simple randomization, 204 mother-infant pairs from selected health institutions were assigned to the intervention group, which received routine health education and short message service reminders, and 204 mother-infant pairs to the control group, which received only routine health education. Mother-infant pairs were used as the randomization units and were randomized 1:1 into one of the two study arms. The data were exported to STATA version 14 statistical software for analysis after being cleaned and coded in EpiData version 4.1. The descriptive statistics were calculated first. To compare outcomes between study groups, log-binomial regression analyses and two-sample tests of proportions were employed. Variables were considered statistically significant when their p-value was less than 0.05. Four hundred mother-infant pairs were enrolled in the trial, 200 of whom were in the control group and 200 of whom were in the intervention group. Eight mother-infant pairs were excluded from the analysis as they had been relocated outside the study area. Compared with the control group, a higher percentage of infants in the intervention group received Penta 1, 199 (99.5%) vs. 191 (95.5%), Penta 2, 192 (96%) vs. 157 (78.5%), and Penta 3, 172 (86%) vs. 133 (66.5%). At 14 weeks, the Penta 3 vaccine was administered to 172 (86%) and 133 (66.5%) infants in the intervention and control groups, respectively. The corresponding risk ratio (RR) was 1.29, with 95% CIs (1.15–1.45; p < 0.001). Additionally, the Penta 3 vaccine was administered on time to 159 (79.5%) and 123 (61.5%) infants in the intervention and usual care groups, respectively, with RRs of 1.29 and 95% CIs (1.13, 1.47; p < 0.001). In this study, 13.6% of infants in the intervention group and 31.4% in the control group dropped out of the Penta 3 immunization program. Despite a dropout rate exceeding an acceptable threshold, the intervention group demonstrated a significantly lower Penta 3 dropout rate than the control group. Our research showed that using a mobile health application through SMS reminder system can increase vaccination timeliness and coverage and strengthen the quality and effectiveness of an immunization program. The intervention substantially improved both the uptake and timely administration of the Penta vaccines compared to usual care. It is therefore recommended that the intervention approach be integrated into routine immunization programs to enhance vaccination coverage and timeliness among infants. Retrospective registration on the Pan African Clinical Trial Registry on March 24, 2025, PACTR202503488120509.