Leveraging Community Health Workers and a Responsive Digital Health System to Improve Vaccination Coverage and Timeliness in Resource-Limited Settings: Protocol for a Cluster Randomized Type 1 Effectiveness-Implementation Hybrid Study (Preprint)

Abstract

BACKGROUND Tanzania is one of 20 countries where the majority of un- and under-vaccinated children reside. Prior research identified substantial rural-urban disparities in coverage and timeliness of childhood vaccinations in Tanzania, with children in rural settings being more likely to receive delayed or no vaccinations. Further research is necessary to identify effective, scalable interventions that can bridge rural-urban gaps in childhood vaccination while accounting for multifaceted barriers to vaccination. OBJECTIVE This protocol describes a type 1 effectiveness-implementation hybrid study to evaluate Chanjo Kwa Wakati (“Timely Vaccination” in Kiswahili), a community-based, digital health intervention to improve vaccination timeliness. The intervention combines human resources (community health workers), low-cost digital strategies (digital case management, task automation), a vaccination knowledge intervention, and insights from behavioral economics (reminders, incentives) for promoting timely childhood vaccinations. METHODS The study will be conducted in two predominantly rural regions in Tanzania with large numbers of un- or under-vaccinated children: Shinyanga and Mwanza. Forty rural health facilities and their catchment areas (“clusters”) will be randomized to an early or delayed onset study arm. From each cluster, three cohorts of mother-child dyads, one retrospective cohort and two prospective cohorts, will be enrolled into the study. The timeliness and coverage of all vaccines recommended during the first year of life, will be observed for 1200 children (600 intervention children and 600 non-intervention children). The primary effectiveness outcome will be the timeliness of the third dose of the pentavalent vaccine (Penta3). Quantitative surveys, vaccination records, study logs, fidelity checklists, and qualitative interviews with mothers and key informants will be used to inform the five constructs of the Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) framework. Results will be used to develop an implementation blueprint to guide future adaptations and scale-up of Chanjo Kwa Wakati. RESULTS The study was funded in August 2022. Data collection is expected to last from February 2024 to July 2027. CONCLUSIONS This study will address the lack of rigorous evidence on the effectiveness of community-based digital health interventions for promoting vaccination coverage and timeliness among children from sub-Saharan Africa and identify potential implementation strategies to facilitate the deployment of vaccination promotion interventions in low- and middle-income country settings. CLINICALTRIAL The trial was registered at clinicaltrials.gov on September 6, 2023 (NCT06024317).