Vaccine hesitancy as indecision: Creation and evaluation of the Unidimensional Vaccine Hesitancy Scale.

Background: Several authors have argued that vaccine hesitancy should be conceptualized as indecision in the vaccination decision-making process, but no established measure with support for its psychometric properties and validity has been created from this operational definition.

Aims: To resolve this tension, this article undergoes a four-study scale development process to create the 4-item Unidimensional Vaccine Hesitancy Scale (UVHS).

Materials and methods: We conduct four survey studies utilizing a total sample size of 884.

Results: In Studies 1 (n = 297) and 2 (n = 298), we provide psychometric support for the measure via exploratory and confirmatory factor analysis. In Studies 3 (n = 193) and 4 (n = 106), we support the concurrent and discriminant validity of the measure by assessing its relations with relevant constructs, such as vaccination readiness and acceptance, and we also provide initial indicators of the scale's possible predictive qualities by testing its time-separated effects with vaccination willingness, receipt and word-of-mouth.

Discussion: We leverage these results to provide a number of theoretical insights and suggestions for future practice. Of note, we highlight that different conceptualizations and operationalizations for the same construct can produce notably differing empirical findings, and vaccine hesitancy is no different.

Conclusion: Our cumulative efforts indicate that the UVHS is an appropriate measure to assess vaccine hesitancy as indecision.