Susceptibility to vaccine misinformation and immunization status among caregivers of under‑5s in Kenya, Rwanda, and Nigeria: A cross‑sectional study

This preregistration covers a nested sub-study within a larger multi-country caregiver survey conducted under the REACH-OUT project. The broader survey aims to understand barriers and enablers to childhood immunization among caregivers of children under five years in Kenya, Rwanda, and Nigeria. The overall instrument includes modules on socio-demographics, behavioural and social drivers of vaccination, health-service access, and child vaccination status. The present preregistration focuses specifically on the misinformation-susceptibility component of that larger study. This module is designed to measure caregivers’ agreement or disagreement with common vaccine-related misinformation statements (e.g., regarding safety, infertility, or conspiracy beliefs). These responses will be combined into a Susceptibility to Vaccine Misinformation (SVM) index, reflecting each caregiver’s relative susceptibility to misinformation. We will survey primary caregivers of children aged 0–59 months in Kenya, Rwanda, and Nigeria (600 participants per country; total N = 1,800). The SVM index will be analyzed in relation to: Child vaccination status (three categories: fully vaccinated for age, under-vaccinated, zero-dose — operationally defined as no DTP1), and Caregiver vaccination intentions (intent to bring the child for all, some, or none of the recommended vaccines). Data collection has not yet begun. All misinformation items will be pre-tested with caregivers through cognitive interviews and small-scale piloting to ensure clarity, cultural relevance, and validity before full implementation. All data for this sub-study will be collected concurrently with the broader caregiver survey, using the same sampling frame, fieldwork procedures, and ethical safeguards. Analyses in this preregistration will therefore focus exclusively on the quantitative data from the misinformation module and its associations with vaccination outcomes and intentions.