Effect of Mobile Text Message Reminders on Routine Childhood Vaccination: A Systematic Review and Meta-analysis

"This review highlights the potential benefits to childhood vaccine uptake of incorporating text message reminders into the standard management of childhood immunizations especially in low- and middle-income countries."

Barriers to vaccination compliance lead 23.3% to 76.3% of parents in developing countries to fail to complete the vaccination programme. Among the barriers are confusion and difficulty in tracking vaccination schedules and missing due dates. Demand-side interventions, including text message reminders, have the potential to reduce dropouts from vaccination by targeting characteristics such as forgetfulness. This review summarises the available evidence on the effectiveness of text message reminders as compared to standard care on childhood vaccination.

Through a process detailed in the article, a total of 1,771 articles were searched, 10 of which met the inclusion criteria. These studies were conducted in the United States (5), Kenya (2), Nigeria (1), Guatemala (1), and Zimbabwe (1). Key findings of the meta-analysis:

• There is a significant effect of text message reminders on childhood vaccination coverage (risk ratio (RR)=1.11; 95% confidence interval (CI) 1.05-1.17).
• In studies from high-income countries, the effect of a text message on childhood vaccination was positive and statistically insignificant (RR=1.06; 95% CI 0.96-1.18) with moderate heterogeneity. On the other hand, there was a statistically significant positive effect of text message reminders among low- and middle-income countries, or LMICs (RR=1.13; 95% CI 1.06; 1.21) with moderate heterogeneity.
• Those studies in which the last reminder messages were sent on the due date had a statistically significant positive effect (RR=1.17; 95% CI 1.11-1.22) on childhood vaccination with no heterogeneity. Similarly, sending reminder text messages 1 day before the due date had a significant positive effect (RR=1.14; 95% CI 1.02-1.28) on childhood immunisation with substantial heterogeneity. However, sending the text messages 2 or more days before the due date has no significant effect on childhood immunisation coverage (RR=1.05, 95% CI 0.96-1.13) with low heterogeneity.
• Sending 2 text messages for one schedule visit had a statistically significant effect on childhood vaccination (RR=1.09; 95% CI 1.01-1.18) with moderate heterogeneity.

Thus, the pooled estimate revealed that there is a potential for text message reminders to improve childhood vaccination rates. However, the included studies showed moderate heterogeneity, which could result from clinical differences across studies. The precise effectiveness of these interventions is likely to be influenced by numerous factors such as country setting and nature of the interventions used. In addition, the frequency and timing of the text message reminders are crucial in determining the effectiveness of text message reminders on childhood vaccination.