The Vaccine Trust Framework: mixed-method development of a tool for understanding and quantifying trust in health systems and vaccines

Abstract

Background Trust is a key component of vaccine demand, yet there is a lack of consensus on how to define trust alongside a lack of actionable, contextually grounded measurement tools validated in low-income and middle-income countries. This study aimed to develop and validate a contextually relevant trust framework and measurement tool, that can lever trust to drive resilient demand. Methods An exploratory sequential mixed-methods study was conducted. Ethnographic research in Nigeria, Kenya, and Pakistan was undertaken to define trust in the context of childhood, human papillomavirus, and COVID-19 vaccines. The generated Vaccine Trust Framework was validated by fielding a nationally representative survey containing the constructed trust measurement tool to caregivers of adolescents in Kenya and Pakistan. Psychometric properties of the survey and associations between trust and vaccination behaviours were assessed using confirmatory factor analysis and logistic regression. Findings The Vaccine Trust Framework, established through synthesis of ethnographic research, contains four interlinked domains—health system promise, health system delivery, vaccine promise, and vaccine delivery— and 15 measurable dimensions. Survey data were collected from 3670 participants in Kenya and 3734 in Pakistan. Trust was observed to influence vaccine behaviour and intentions, which was further supported by associations between quantitative trust scores and vaccination status across the studied vaccines. Regional trust variation was observed within Kenya and Pakistan, with patterns matching qualitative findings on the perceptions of local vaccine and health systems. Interpretation The Vaccine Trust Framework provides a validated, contextually grounded tool for assessing trust in health systems and vaccines in low-income and middle-income countries. The Vaccine Trust Framework can be used as a prognostic tool, intervention design aid, or trust measurement tool within an intervention or monitoring study. Further research is in progress to assess its utility in designing and measuring the effect of trust-building interventions.