What drives adult vaccine hesitancy? Content and face validation of a new measure for U. S. Adults

Abstract

Background Vaccine hesitancy is viewed as a complex interaction of behavioral and societal factors that can intervene in the uptake of vaccines or lack thereof. To date, no existing instrument developed for the U. S. adult population measures general vaccine hesitancy in a way that integrates behavioral and cognitive determinants and generalizes across vaccines rather than targeting a specific disease. The development of this tool will be useful for clinicians to counsel patients on vaccination and for vaccine related public health interventions targeted at improving population health. Methods Based on a comprehensive review of the literature, 38 items were developed to be rated on a 5-point Likert scale. Eight subject matter experts across the United States completed a content validity review to determine the relevance of survey items. Face validity feedback was collected from three self-reported vaccine-hesitant, one with a neutral stance on vaccines, and three not vaccine-hesitant individuals. Results Item-Level CVI (I-CVI) ranged from 0.38 to 1.00 for the initial 38 items. Five items were dropped due to low CVI scores, face validity feedback, and similarity to other items. Four items were revised to incorporate the viewpoints of comparable items, address face validity feedback, and improve overall clarity and alignment with the survey’s objectives. Lastly, two items below the I-CVI threshold of 0.80 were retained after the research team deemed them necessary for addressing general vaccine hesitancy in the adult population. The Scale-Level CVI (S-CVI) was 0.87 across all 38 items initially rated and 0.90 for the final 33-item scale, indicating strong content validity, and the final survey consists of 33 items. Conclusion This tool lays the groundwork for better understanding the barriers associated with vaccination and hesitancies that prevent the growth of herd immunity and overall vaccination uptake. Pilot testing on a large sample of the adult population is required to refine the tool items further.