Psychometric properties of the adapted measles vaccine hesitancy scale in Sudan

Background: There is a need for reliable and validated tools to identify, classify, and quantify vaccine-hesitancy in low and middle-income countries, such as Sudan. We evaluated the psychometric properties of an adapted version of the measles vaccine hesitancy scale by assessing its reliability, convergent validity, and criterion validity in Sudan. The vaccine hesitancy scale (VHS) was originally developed by the WHO/SAGE Working Group of Vaccine Hesitancy. Methods: A community-based survey among parents was conducted in February 2019 in Khartoum state. We conducted exploratory and confirmatory factor analysis to examine the structure of the adapted measles VHS (aMVHS). We computed Cronbach’s alphas, correlations with other vaccine hesitancy measurements including the Parental Attitude towards Childhood Vaccination (PACV) and the Vaccine Confidence Index (VCI), and performed a Mann-Whitney U test for assessing the reliability and the convergent and criterion validity, respectively. Moreover, to examine whether the aMVHS can predict the child’s vaccination status, the area under the curve (AUC) was estimated using receiver operator characteristic (ROC) curves. Results: The questionnaire was completed by 500 parents. Most were women (87.2%) between the ages of 20 and 47 (M = 31.15, SD = 5.74). The factor analyses indicated that the aMVHS comprises of two factors (sub-scales): 'confidence' and 'complacency'. The aMVHS sub-scales correlated weakly to moderately with the PACV and VCI scales. The area under the curve was 0.499 at most (P >0.05) and the aMVHS score did hardly differ between actually vaccinated and non-vaccinated children. Conclusion: Our findings underscore that the aMVHS and its confidence and complacency sub-scales are reliable and have a moderately good convergent validity. However, the aMVHS has a limitation in predicting the concurrent child's vaccination status. More work is needed to revise and amend this aMVHS, particularly by additionally including the 'convenience' construct and by further evaluating its validity in other contexts.