Validation of the vaccination attitudes examination scale in a South African context in relation to the COVID-19 vaccine: quantifying dimensionality with bifactor indices

Abstract

Background: The COVID-19 pandemic represented a global public health emergency. Existing studies support the view that vaccination and mass immunization are among the most effective means of containing the outbreak and promoting health. However, negative attitudes toward vaccination and the related vaccine hesitancy among many groups have created a significant barrier to effectively managing the health crisis. Having a valid and reliable tool to assess attitudes toward vaccination remains imperative so that factors underlying vaccine refusal can be identified and public health interventions can be facilitated. The current study examined the psychometric properties of the Vaccination Attitudes Examination Scale (VAX) in South Africa.

Methods: Participants (n = 322) completed the VAX. Confirmatory factor analysis and ancillary bifactor indices were used to examine the hypothesized factor structure (a total scale and four subscales) of the scale. Inter-item correlations, factor loadings, and average variance extracted were used to examine the validity of the scale. Predictive validity was examined by comparing those who had received the COVID-19 vaccine and those who had not. The reliability of the scale was examined in terms of both Cronbach's alpha and composite reliability.

Results: Confirmatory factor analysis provided support for the conceptualization of the scale as consisting of a total scale and four subscales, and ancillary bifactor indices indicated that the subscales accounted for a sufficient amount of variance (44%) after the variance explained by the total scale was considered. Overall, the analysis indicated that the scale had satisfactory reliability (alpha and composite reliability = 0.70) and provided evidence for the construct, convergent, and predictive validity of the VAX.

Conclusions: The sound psychometric qualities of the scale, when used in a low- to middle-income country, have the potential to advance research and immunization policy within these settings and facilitate more targeted interventions to promote vaccine uptake.