A systematic review pooled 22 randomised controlled trials of digital health interventions for paediatric immunisation in low- and middle-income countries, covering 68,664 participants. Reminder-only interventions raised coverage of target vaccines (RR 1.27, 95% CI 1.09 to 1.49) and reminders combined with education raised it further (RR 1.72, 95% CI 1.38 to 2.15), with timely pentavalent receipt also improved (RR 1.55). Heterogeneity was substantial for most pooled estimates (I2 up to 95%), and the reminder effect was larger in urban (RR 1.14) than rural (RR 1.05) settings.
Why it is interesting: The pooled gain from reminders alone is set against reminders with education, and the reminder effect is larger in urban than rural settings.