Development of a US trust measure to assess and monitor parental confidence in the vaccine system.

Abstract: To develop a Vaccine Confidence Index (VCI) that is capable of detecting variations in parental confidence towards childhood immunizations centered on trust and concern issues that impact vaccine confidence. Methods: We used a web-based national poll of 893 parents of children <7 years in 2016 to assess the measures created for the Emory VCI (EVCI). EVCI measures were developed using constructs related to vaccine confidence identified by the U.S. National Vaccine Advisory Committee (i.e., “Information Environment”, “Trust”, “Healthcare Provider”, “Attitudes and Beliefs”, and “Social Norms”). Reliability for EVCI was assessed using Cronbach’s alpha. Using the variables related to each of the constructs, we calculated an overall EVCI score that was then assessed against self-reported childhood vaccine receipt using chi-square and the Cochrane-Armitage trend tests. Results: Respondents’ EVCI scores could range from 0 to 24, and the full range of values was observed in this sample (Mean = 17.5 (SD 4.8)). EVCI scores were significantly different (p ≤ 0.006 for all comparisons) between parents who indicated their child(ren) received routinely recommended vaccines compared with parents who indicated they had delayed or declined recommended immunizations. There was also a significant, consistent association between higher EVCI scores and greater reported vaccine receipt. Conclusions: We developed EVCI to reliably measure parental vaccine confidence, with individuals’ scores linked to parental vaccine-related attitudes, intentions, and behaviors. As such, EVCI may be a useful tool for future monitoring of both population and individual confidence in childhood immunization.