Effect of SMS Reminders on Childhood Vaccination Coverage in Rural Sub- Saharan Africa: A Systematic Review Protocol

BackgroundImmunization coverage remains suboptimal in rural regions of Sub-Saharan Africa, where structural and behavioural barriers limit access to routine childhood vaccines. With mobile phone use expanding across the continent, short message service (SMS) reminders have emerged as a potential strategy to improve immunization adherence. However, the impact of such interventions in rural and semi-rural African settings has not been systematically reviewed. ObjectiveThis review aims to evaluate the effectiveness of SMS reminders in improving childhood vaccination outcomes--including coverage, timeliness, and dose completion--among children residing in rural and semi-rural areas of Sub-Saharan Africa. MethodsThe review will follow PRISMA 2020 guidelines. Electronic databases to be searched include PubMed, Scopus, Web of Science, Google Scholar, African Journals Online (AJOL), WHO IRIS, UNICEF Evaluation Database, and ProQuest Dissertations and Theses. Eligible studies will include randomized controlled trials, cluster randomized trials, and quasi-experimental designs published between January 2014 and March 2024. Two reviewers will independently screen records, extract data, and assess study quality using the Cochrane RoB 2 and ROBINS-I tools. A narrative synthesis will be performed due to expected heterogeneity in study designs and outcome measures. Expected OutcomesThe review will provide context-specific insights on how SMS reminders affect immunization uptake in rural settings. It will highlight effective intervention strategies, identify implementation challenges, and inform digital health programming for immunization equity in Sub-Saharan Africa. RegistrationThis protocol is not registered in PROSPERO.