Study protocol for a cluster-randomised controlled trial of hybrid parents and health workers adaptive intervention for optimal routine childhood immunisation coverage in the communities of Ebonyi state, Nigeria: the AGINTOPIC trial protocol.

INTRODUCTION: Vaccine-preventable infectious diseases (VPDs) are major causes of morbidity/mortality among children under 5 years of age worldwide and in Nigeria/Ebonyi state. Routine childhood immunisation is an invaluable prevention strategy for many VPDs. Due to suboptimal coverage and untimely receipt/delay in receipt of vaccinations, outbreaks of VPDs such as measles, yellow fever, diphtheria and others continue to reoccur around the world and in Nigeria/Ebonyi state. This study aims to evaluate the effectiveness of hybrid parents and health workers adaptive intervention in increasing the optimal/timely (cumulative age-appropriate) routine childhood immunisation coverage in the communities in Ebonyi state, Nigeria. METHODS AND ANALYSES: A two-arm, parallel, open label, covariate-constrained cluster-randomised controlled trial with 1:1 allocation of 16 geographical clusters (the nearest catchment areas for at least one public primary healthcare (PHC) facility with at least 500 households or a population size of 3000) will be used to evaluate the effects of hybrid/combined parents and PHC workers adaptive engagement compared with control. The primary outcomes are the optimal/timely (cumulative age-appropriate) receipt of the recommended vaccines in the routine childhood immunisation schedule by children aged 5-9 completed months and 10-11 completed months and the age-appropriate vaccines receipt score for the recommended vaccines. The outcomes will be measured through a population-based household survey of at least 15 children aged 5-9 and 10-11 months per cluster at baseline and at the end of the study using a structured interviewer-administered questionnaire in KoBoCollect installed in android devices. All analyses will be done using a cluster-level method on as-randomised basis. ETHICS AND DISSEMINATION: Ethical approval for the trial was obtained from the Ebonyi State Health Research and Ethics Committee (EBSHREC/01/06/2022-31/05/2023) and verbal consent will be obtained from participants. Study findings will be reported at local/national and international levels as appropriate. TRIAL REGISTRATION NUMBER: ISRCTN59811905.