Automated phone call and text reminders for childhood immunisations (PRIMM): a randomised controlled trial in Nigeria

BACKGROUND: Sub-Saharan Africa has high under-5 mortality and low childhood immunisation rates. Vaccine-preventable diseases cause one-third of under-5 deaths. Text messaging reminders improve immunisation completion in urban but not rural settings in sub-Saharan Africa. Low adult literacy may account for this difference. The feasibility and impact of combined automated voice and text reminders on immunisation completion in rural sub-Saharan Africa is unknown. METHODS: We randomised parturient women at the Mother and Child Hospitals Ondo State, Nigeria, owning a mobile phone and planning for child immunisation at these study sites to receive automated call and text immunisation reminders or standard care. We assessed the completion of the third pentavalent vaccine (Penta-3) at 18 weeks of age, immunisation completion at 12 months and within 1 week of recommended dates. We assessed selected demographic characteristics associated with completing immunisations at 12 months using a generalised binomial linear model with ‘log’ link function. Feasibility was assessed as proportion of reminders received. RESULTS: Each group had 300 mother−baby dyads with similar demographic characteristics. At 18 weeks, 257 (86%) and 244 (81%) (risk ratio (RR) 1.05, 95% CI 0.98 to 1.13; p=0.15) in the intervention and control groups received Penta-3 vaccine. At 12 months, 220 (74%) and 196 (66%) (RR 1.12, 95% CI 1.01 to 1.25; p=0.04) in the intervention and control groups received the measles vaccine. Infants in the intervention group were more likely to receive Penta-3 (84% vs 78%, RR 1.09, 95% CI 1.01 to 1.17; p=0.04), measles (73% vs 65%, RR 1.13, 95% CI 1.02 to 1.26; p=0.02) and all scheduled immunisations collectively (57% vs 47%, RR 1.13, 95% CI 1.02 to 1.26; p=0.01) within 1 week of the recommended date. No demographic character predicted immunisation completion. In the intervention group, 92% and 86% reported receiving a verification reminder and at least one reminder during the study period, respectively. CONCLUSION: Paired automated call and text reminders significantly improved immunisation completion and timeliness. TRIAL REGISTRATION NUMBER: NCT02819895.