The world as we know it changed during the COVID-19 pandemic. Although hope has emerged with the development of new vaccines against the disease, public health providers still face a significant challenge in ensuring uptake of those vaccines by the larger public. To achieve herd immunity to COVID-19, a substantial proportion of the population would need to be vaccinated [1]. However, there are many factors hindering vaccine uptake, including logistic and economic factors and misinformation leading to a lack of public confidence in the effectiveness and safety of the vaccines [1,2]. These are all factors that contribute to what has been termed vaccine hesitancy. Vaccine hesitancy is defined as the “refusal or delay of the uptake of vaccines despite the availability of services” [3,4]. Vaccine hesitancy is a global problem that has negatively impacted public health. The World Health Organization (WHO) Strategic Advisory Group of Experts on Immunization (SAGE) established a working group to address this issue [3].

Understanding the factors affecting vaccine hesitancy and how to assess its prevalence have become imperative amid the COVID-19 pandemic. Developing new vaccines utilizing existing or new technologies spurred public scrutiny regarding the need, safety, and efficacy of such vaccines [1,2]. This prompted a need for a tool to help assess vaccine hesitancy among adults. Before this, vaccine hesitancy scales (VHS) available in the literature focused on parental attitudes and perceptions regarding vaccinating their children [5]. Various attempts were made to develop or adapt parental VHS tools for adults, but very few went through the rigor of being validated [5-8]. The need for such a validated scale has only increased with the COVID-19 pandemic.

Various scales have been developed to measure hesitancy among parents or health care workers [5]. The WHO SAGE Working Group on Vaccine Hesitancy developed a 10-item VHS that is widely used in different countries and settings [9]. The VHS has been modified to the adult VHS (aVHS) and has been adapted and validated in English and Chinese [5].

The aVHS is a 10-item scale with a 5-point Likert scale ranging from “Strongly disagree” to “Strongly agree.” The Likert scale items have scores ranging from 10 to 50, where 50 represents the highest degree of vaccine hesitancy and 10 represents the lowest. The scores on 7 items on the scale will be reverse coded so that the highest scores reflect the highest degree of vaccine hesitancy. A cut-off score of 24 is used to dichotomize the outcome into “vaccine hesitant” and “not vaccine hesitant” categories. The score range and cut-off score have been proposed and validated by the research team developing the scale [5].

To our knowledge, no available aVHS has been designed or validated in Arabic or French.

Both of these languages are widely used in the countries included in the WHO Regional Office of the Eastern Mediterranean (EMRO) [10], with Arabic being the most commonly used language in EMRO and French being a commonly used language in EMRO countries such as Algeria, Tunisia, Morocco, and Djibouti. For the aVHS to be valid for these populations, the scale must undergo translation and cultural adaptation prior to validation and reliability testing. This study will adopt a rigorous methodology to translate and validate the aVHS and conduct a proper psychometric evaluation of the translated version to make the scale available to all scholars in the EMRO region and beyond. In addition, we plan to survey a representative sample of the region to assess the aVHS’ structure, internal consistency, and validity across different social and demographic settings. Therefore, this research aims to translate the aVHS from its original English language to Arabic and French and validate the translations in the WHO Eastern Mediterranean region.

No identifying information will be collected from participants in any of the study phases. Data will be collected and stored on local MBRU servers. Data collected for the validation of the prefinal version phase will be anonymously collected via a link to an online survey hosted on a website hosted locally. The link will be posted on different social media platforms, and only the research team will have access to the data.

The study is part of the research project titled “Addressing Vaccine Hesitancy through Targeted and Personalized Mobile Educational Interventions for Different Populations in the Eastern Mediterranean region.”

The study has been reviewed and approved by the institutional review board of Mohammed Bin Rashid University of Medicine and Health Sciences (MBRU IRB-2021-87).

Data analysis in each phase will follow the steps explained in the preceding paragraphs. Statistical analysis software will be used to analyse the data set. A complete case analysis approach will be adopted. Data will be tested for normality, visually using histograms and statistically using the Shapiro-Wilk test. The significance level cut-off will be set at P<.05, and exact P values will be reported.

This study is part of a group of studies conducted by the Institute for Excellence in Health Professions Education (ieHPE) at MBRU, located in Dubai, United Arab Emirates. These studies are all taking different approaches to address vaccine hesitancy. The original, English-language version of the aVHS is being used as part of these studies (unpublished). We selected the aVHS as it is one of very few tools to have undergone validation prior to implementation. In this project, we will be translating and validating the scale for countries included in the WHO EMRO [10], in which most of the population speak Arabic and/or French. We reviewed the literature and found existing VHS in Arabic; however, none of them have undergone a rigorous validation process [22-25]. Such a process is needed to clarify the underpinnings of the scale factor loadings, structure, and stability. For example, suppose we aim to understand vaccine hesitancy in our region. In that case, we cannot simply rely upon scales that have been validated in a different setting; surveys, questionnaires, and scales, in general, cannot be validated unless they have been validated and tested on the population in which they are planned to be used [26]. Our objective is to adopt a rigorous methodology to ensure validity and reliability of the tool.

Sample size assessment was also an issue we encountered while planning the study. There is no clear consensus in the literature for the sample size calculation required for scale validation. For example, published studies mentioned that 1000 was an ideal sample size [12,17], while others reported that 10 subjects per item would be sufficient [11]. This would have reduced the proposed sample size from 1000 to 100 for this 10-item scale study. It was also previously mentioned that 300 to 500 subjects are required to perform an EFA [12]. We chose the sample size for this study because it ensures we will be able to conduct the analysis proposed.

Our literature review also uncovered that sociodemographic factors and differences in the political climate are potentially reflected in vaccine hesitancy status [3,26,27]. Interestingly, although overall health in general has commonly been associated with higher educational level [3], those with higher educational levels have been shown to have a greater hesitancy to vaccinate [3], even among health care providers [27], demonstrating that underlying social determinants are different than with overall health. The sociodemographic factors that are correlated with vaccine hesitancy have been explored in some studies in the region [28]. Still, most have focused on a single country [25], while other studies did not address these factors [24,29]. This study aims to explore those factors across different countries in the region. In addition, the relationship between vaccine hesitancy and actual vaccination will be explored and reported in this study. Although some countries mandate vaccination for their citizens and some pose some restrictions on unvaccinated individuals, vaccine hesitancy as a perspective might be independent of actual vaccination. This is a meaningful relationship to explore to understand the population’s attitude toward vaccines and actual behaviors potentially influenced by governments’ mandates.

One of the limitations of the protocol is the convenience sampling approach utilized. Although convenience sampling could potentially introduce bias to the study results, it is still a practical approach utilized by various studies, especially in the absence of a sampling frame. We expect this to be a minor issue in phase 3 of the study as this phase aims to test the translation only. As for phase 4, data stratification and regression models will allow us to elucidate and control for potential bias. Another limitation is posting the survey online. We are aware that this impacts the generalizability of the results, since only people with electronic devices, internet connection, and a degree of digital literacy will be able to access the survey and may not be representative of the rest of the population. But since this protocol proposes translating and validating the scale and does not aim at measuring the prevalence of vaccine hesitancy, we hypothesize that the impact should be minor.

This study will provide researchers with a validated tool to assess adult vaccine hesitancy within populations that speak Arabic or French and provide a road map on how to scale translation and ensure cross-cultural adaptation. We aim at supporting our approach with statistical evidence.

Any work resulting from this project will be disseminated nationally and internationally through submission to academic journals and international conferences.