Systematic review of mHealth and digital health interventions to improve childhood vaccination uptake in 19 Sub-Saharan African countries

Mobile health and digital health (mHealth/DH) interventions have been shown to support immunisation programmes in Sub-Saharan Africa (SSA) and improve uptake of life-saving vaccines. As 19 SSA countries were targeted to begin rolling out the two new malaria vaccines (RTS,S/AS01 and R21/Matrix-M) in 2024, this systematic review aims to investigate which mHealth/DH interventions are most effective at increasing vaccination uptake (by assessing vaccination coverage and timeliness outcomes) in these countries. The review assessed the effectiveness of mHealth/DH interventions for increasing uptake of Diphtheria-Tetanus-Pertussis or Pentavalent vaccines (DTP/Pentavalent). As with any multi-dose vaccine, the DTP/Pentavalent vaccine requires multiple doses to ensure its maximum protective benefit, therefore maintaining schedule adherence and ensuring its timely completion is essential. Thus, identifying strategies to support adherence, such as digital appointment reminders, remains a public health priority. Eight electronic databases were searched, alongside selected grey literature sources. A narrative synthesis was conducted with studies grouped by mHealth/DH intervention-type. Included studies were assessed for risk of bias using RoB2 and ROBINS-I, and certainty of evidence was evaluated using the GRADE approach. 14 studies were included, comprising both randomised and non-randomised control trials. However, only 4 out of the 19 SSA countries were represented (Nigeria, Kenya, Burkina Faso and Cote D'Ivoire). All interventions investigated were appointment reminders. Generally, all intervention-types were positively associated with vaccination coverage and timeliness. SMS-based interventions showed modest effects, whereas interventions incorporating voice components (phone calls/voice messages) tended to yield larger effects. The certainty of evidence ranged from very low to moderate depending on the intervention-type and outcome pairing. The findings offer evidence-based insights to guide the development and implementation of mHealth/DH interventions within SSA childhood immunisation programmes. While interventions with voice-based components appear particularly promising, the limited certainty of evidence demonstrates further high-quality, context-specific research is required to draw stronger conclusions.