13 September 2022

Vaccinations are considered one of the most effective public health interventions. However, vaccination coverage rates have decreased and subsequent vaccine-preventable diseases have increased due to people’s hesitancies regarding vaccines. Therefore, the World Health Organization considers vaccine hesitancy to be a top-10 global health threat.

Researchers from different disciplines within the medical and social sciences have studied vaccine hesitancy (VH). The concept of VH has been described and applied in various ways and used interchangeably with vaccine confidence, low uptake of vaccines and low intention to vaccinate. These different conceptualizations lead to inconsistencies, unclarity and incomparable study results.

Daphne Bussink-Voorend conducted a systematic review with Jeannine Hautvast, Olga Visser (ELG) Lisa Vandeberg (Radboud University) and Marlies Hulscher (IQ healthcare) to provide an overview of VH definitions and applications in scientific literature. They have published their outcomes in Nature Human Behavior. The analysis reveals that VH gives expression to thoughts and feelings regarding vaccination (e.g., having concerns about the safety of vaccines), exhibited behaviour (e.g. refusal of a vaccine), and/or decision making regarding vaccination (e.g., being undecided about vaccination). Thus, the concept is used heterogeneously, even within these categories. 

A wide variety of measurement instruments have been used to measure and identify VH, ranging from complex instruments with various subscales to a single question (e.g., ‘Have you ever refused vaccination?’). These instruments partly align with the three conceptual categories, but also include other conceptualizations including intention (e.g., how likely is it that you will take the vaccine once it becomes available?) and willingness (e.g., how willing are you to take the vaccine?). The findings demonstrate the varied and confusing use of VH, a mismatch between the VH concept and measures, and the need for clarification.

Based on the findings, the authors argue to adapt the VH concept from a broad and inclusive form to a pragmatic and refined alternative to achieve uniformity with in the research field and aide comparability between research results. As a way forward, vaccine hesitancy is proposed to be defined as a psychological state of indecisiveness that people may experience when making a vaccination decision.

 

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