Effect of Mobile Phone Text Message Reminders on the Completion and Timely Receipt of Routine Childhood Vaccinations: Superiority Randomized Controlled Trial in Northwest Ethiopia

"[T]ext message reminders can be an additional tool to usual care for improving timely completion of childhood vaccinations in resource-limited settings."

In low-income countries, failure to attend vaccination appointments contributes to delayed and missed vaccinations. Forgetfulness and being unaware of the need to return for subsequent doses have been found to be common reasons for nonattendance, which are remediable through appropriate reminder services. In Ethiopia, mobile phone technology access is expanding rapidly, and mHealth interventions may have a role to play in improving Ethiopia's immunisation programme. This trial was conducted to assess the effect of a locally developed mobile phone text message reminder system in improving child vaccination service uptake in Gondar city, northwest Ethiopia.

The randomised controlled trial was conducted in Gondar city's 9 public health facilities between May 2019 and June 2020. The baseline assessment in the study area indicated that 78.9% (360/456) of the mothers had the intention to use mobile phone text message reminders for child vaccination. The assessment also pointed out that among mothers who owned a mobile phone, 91.0% (415/456) can read text messages, which makes the trial feasible in the study setting.

Participants assigned to the intervention group received the routine vaccination appointment reminder and additional mobile phone text message reminders in Amharic and English one day before the scheduled vaccination visits on the sixth week, tenth week, fourteenth week, and ninth month after childbirth. The eHealthLab Ethiopia research team developed a computerised text message reminder system for this particular study considering the local context. It has 2 components: a web-based application for client registration and automatic reminder scheduling. Participants in the usual care group used vaccination cards and were informed of the due date of the next vaccination schedule verbally by healthcare providers during the facility visit.

A total of 426 participants were included in the analysis. The proportion of infants who completed the 12-month vaccination series in the intervention group was significantly higher than that of infants who completed that same series in the usual care group (176/213, 82.6% vs 151/213, 70.9%, respectively; one-tailed P=.002). Similarly, comparisons in the timeliness of vaccination among the study groups revealed that timely completion of vaccination in the intervention group was significantly higher than that in the usual care group (135/213, 63.3% vs 85/213, 39.9%, respectively; one-tailed P<.001). In addition, the timeliness of vaccination was compared between fully vaccinated infants in the intervention (n=176) and fully vaccinated infants in the usual care group (n=151). The findings showed that of those fully vaccinated infants in both groups, 135 (76.7%) in the intervention group and 85 (56.3%) in the usual care group were fully vaccinated on time.

In this trial, infants from the intervention group also had higher vaccination coverage for specific vaccines as compared to the infants from the usual care group.

Further analysis revealed that mothers in the intervention group were 17% more likely to fully vaccinate their infants as compared to mothers in the usual care group (risk ratio (RR) 1.17, 95% lower confidence interval (CI) 1.07). Furthermore, mothers in the intervention group were 59% more likely to timely complete all doses of vaccines for their infants as compared to mothers in the usual care group (RR 1.59, 95% lower CI 1.35). The potential impact of the text message reminders was also determined using attributable risk percent. The attributable proportion among those mothers who received mobile phone text message reminders indicated that 37.1% of infants' on-time full vaccination could be attributed to the text message reminders. Of the automatically sent 852 mobile phone text messages, 764 (89.7%) were delivered to the participants.

In outlining implications for practice and research, the investigators note that the digital health literacy of the end users might influence the effective implementation of mHealth interventions in different contexts, which requires prior assessment in future trials. To scale up mobile-phone-based text message interventions in the national immunisation programme of a resource-constrained setting, further studies that guide large-scale implementation are recommended.

Based on the findings, the researchers conclude that: "Locally developed mobile phone text message reminders as a new evolution may contribute to strengthening the routine immunization program and should be considered by policy makers and program managers to improve timely completion of vaccinations."