Abstract
Acceptance of the SARS-CoV-2) COVID-19( vaccine is a very important factor to keep health workers safe. The study aimed to evaluate the psychometric properties of intention to receive the COVID-19 vaccine using a health belief model among health workers in Iran The study was a tools design study that was conducted in the period from February to March 2020, Iran Questionnaire items were designed using text review. The sampling method was multi-stage. Data were analyzed using descriptive statistics, confirmatory and exploratory factor analysis at a 95% confidence level using SPSS software version 16. The designed questionnaire had an appropriate content validity and internal consistency. Also, the exploratory factor analysis showed that a 5-factor structure was extracted and confirmatory factor analyses revealed that the conceptual five-factor structure of the measure had good fit indices. Reliability was evaluated using internal consistency. Cronbach Alpha coefficient was .82 and the intra-class correlation coefficient (ICC) was .9. It can be concluded that the instrument designed in the preliminary stage of psychometrics properties had good validity and reliability indicators. Also, the constructs of the health belief model well explain the determinants of the intention to receive the COVID-19 vaccine at the individual level.
To achieve valid results, access to a valid questionnaire is essential. The application of the health belief model in accepting the COVID-19 vaccine has been tested in some studies. However, in most of these studies, the questionnaires were not valid and the steps of psychometric properties of the instrument were not fully investigated.
In a high sample size study, we designed a tool based on the health belief model (HBM) construct. Furthermore, both the exploratory and confirmatory factor analysis was done for testing construct validity.
The designed questionnaire had an appropriate content validity and internal consistency. The constructs of the health belief model well explain the intention to receive the COVID-19 vaccine at the individual level.
Introduction
Since December 2019, SARS-CoV-2 (COVID-19) has been the cause of acute respiratory syndrome in Wuhan, China. However, due to the high spread of the virus, it has almost changed from an epidemic in China to a pandemic, and most countries in the world, including “X,” are affected by COVID-19 disease. 1 Based on what is currently known about SARS-CoV-2, the spread of the disease from a person infected with the virus often occurs in close contact. There is currently no drug available for COVID-19. 2 The only definitive way to reduce the prevalence of this disease is to create herd immunity. Herd immunity is usually possible through direct infection or immunization of at least 65% of the population using universal vaccination.
Preliminary evidence of direct immunity to the virus indicates that the duration of immunity is limited and, in some cases, reported to be unknown, and the financial, human, medical, and long-term complications of the disease are so high that it completely ignores this policy. The second way, vaccination, in addition to financial and human resources, requires the cooperation of different groups, and different aspects must be considered in its planning. Negative attitudes toward vaccines are one of the major concerns for achieving collective safety.3,4 The second way, vaccination, in addition to financial and human resources, requires the cooperation of different groups, and different aspects must be considered in its planning. Negative attitudes toward vaccines are one of the major concerns for achieving herd immunity.3,4 One of the first steps in assessing behavioral intent and determinants of mass acceptance of COVID-19 vaccination. According to a survey of the general population of 19 countries, the vaccine acceptance rate is 71.5%. The highest acceptance rate in China was approximately 90% and the lowest in Russia was 55%. 5 One of the important measures in increasing the acceptance of vaccination is the use of health education models. 6 One of the effective models in this field is the model of health belief model. 7 This model includes behavioral intent and elements of perceived sensitivity and intensity, perceived benefits and barriers, guided action, and perceived self-efficacy. 7 Perceived susceptibility during the COVID-19 epidemic is when people consider themselves at risk for COVID-19 and perceived severity means that the disease has serious and potential consequences for them. If the perceived benefits outweigh the barriers to vaccination, people will believe that following preventative measures such as getting the COVID-19 vaccine will have a positive effect and reduce symptoms. Therefore, they will be more likely to be able to get the COVID-19 vaccine (self-efficacy). A structure called the action guide also expresses stimuli that affect the person from inside or outside and cause the person to adopt desirable preventive behaviors according to the levels of perceived sensitivity, perceived severity, perceived barriers, and perceived benefits. These variables are thought to be influenced by demographic variables such as race, age, and socioeconomic status. 8 In this regard, Shmueli 9 2021 showed that the intention to receive the COVID-19 vaccine had a significant relationship with perceived benefits, perceived severity, and cue to action. In another study in Greece, the intention to accept a vaccine with perceived benefits had the greatest effect and the perceived sensitivity had the least effect on receiving the vaccine. 10 In Bangladesh, perceived benefits, perceived severity, and perceived barriers were associated with reduced hesitancy about vaccine acceptance in the general population. 11 Based on the published findings, the application of behavioral change models in accepting the COVID-19 vaccine has been tested using a health belief model in the general population. However, in most of these studies, the questionnaires were researcher-made and the steps of psychometric properties of the instrument were not fully investigated or the intention to the received vaccine was measured by a one-item question. To achieve valid results, access to a valid questionnaire is essential.9,12,13 According to various studies, hesitancy/acceptance to get vaccination is attributed to a variety factors, including religious considerations, personal views, and safety worries brought on by common misconceptions.14,15 On the other hand, medical professionals are among the first people to receive the COVID-19 vaccine because they are high-risk populations. Therefore, assessing their views on vaccination is crucial since they have the power to shape public opinion and serve as a reliable benchmark. To our knowledge, there is no valid and reliable scale using HBM to evaluate Iranian context that showed healthcare professionals hesitancy/acceptance to receive the COVID-19 vaccine. The present study was conducted to design and evaluate the psychometric properties of intention to receive the COVID-19 -9 vaccine using a health belief model in the research community of health workers in Iran
Literature Review
The HBM is widely used in behavior change research, which focuses on people’s attitudes and beliefs about their behavior. This theory is used to describe and predict how people behave in terms of their health (ie, vaccination). 16 The HBM had been applied to evaluate public opinion on seasonal and pandemic swine flu vaccines,17,18 as well as to determine the relationship between the individual’s beliefs and the hepatitis B immunizations purchased.19,20 The health belief model has also been a framework for identifying the factors affecting maternal pertussis vaccination during pregnancy. 21 The model has been used to better understand why people engage in vaccination-related health behaviors, as well as to develop COVID-19 programs and interventions to overcome the barriers to changing immunization attitudes. As a result, it is frequently employed as a theoretical framework in studies of Covid 19 immunization recipients.10,22 The intention of health workers to get the Covid 19 vaccine via HBM has been investigated in several cross-sectional studies.23 -26 The Health Belief Model (HBM) implies that those who are afraid of COVID-19 are more likely to get vaccinated because of the perceived benefits.9,25,27 Studies have shown that HCWs are concerned about the vaccine’s efficacy and its side effects, 24 the vaccine’s novelty, manufacturer reliability, and the number of required doses. 26 Because assessing attitudes toward COVID-19 vaccination is so complex, having reliable and effective measurement tools to drive vaccination policy, immunization programs, and community-based efforts and campaigns are crucial. 28 Similarly, the accuracy of standardized methods to assess and evaluate vaccine intention among susceptible populations is based on strong psychometric features. In this field, only a few kinds of research have focused on the development and psychometric evaluation of instruments, among them, the following studies can be mentioned. Huynh et al 12 developed and evaluated a scale based on HBM for COVID-19 vaccines in adults in Vietnam. Also, the psychometric properties of the Health Belief Scales Toward the COVID-19 Vaccine, including the structure, reliability, and validity of the scale, were examined in a general population in Poland by Konaszewski et al. 13 In a cross-sectional study in the United States, Rodriguez et al 28 investigated the psychometric properties of a modified version of the Vaccine Hesitancy Scale (VHS) among people with HIV (PWH) for COVID-19 immunization.
Method
Study Design
This study is a part of a large study, that was conducted in the period from February to March 2020 after approval and obtaining the code of ethics from the Medical Ethics Committee of Zanjan University of Medical Sciences.
Participants
The study population included health workers from 9 provinces of Iran Inclusion criteria included a willingness to participate in the study and having at least three months of work experience in selected sampling centers. The exclusion criteria included unwillingness to continue cooperation and incomplete questionnaires.
Sampling Method
The sampling method was multi-stage, in the first stage, each province was considered a cluster. In each cluster, individuals were randomly selected according to the job and then according to the calculated ratio of sample size in each category. In the center of the province, a COVID-19 center hospital along with another hospital, preferably a general hospital, 5 comprehensive urban health centers, and 5 comprehensive rural health centers were randomly selected and sampled with the specified number of quotas. Information about how participants were selected has been reported in a previous article. 29
Data Collection Procedure
The sample size of 10 to 20 observations per item in factor analysis is usually considered sufficient.30,31 In this study, due to access to sufficient sample size, the sample size was calculated more than the number of items in the questionnaire. We have three separate samplings. The first sample (n = 1227) was used to perform the exploratory factor analysis (EFA), the second sample (n = 400) was used to analyze confirmatory factor analysis (CFA), and the last sample (n = 15) was used to perform consistency reliability analysis (CRA).
Data were collected using an anonymous questionnaire including the demographic questionnaire and the intention to receive vaccines based on HBM constructs. The demographic questionnaire included age, gender, and place of work. In the present study, data were collected through direct attendance by trained staff with observance of health protocols related to COVID-19 such as wearing a face mask, physical distance (of at least one meter), limiting the number of people in close contact, etc. Also, to minimize the rate of disease spread and to comply with the health protocols of COVID-19, the Packed questionnaires were distributed among the selected people and the completed questionnaires were collected in the predetermined schedule.
Designing and Psychometric Properties
The process of designing and psychometric properties of intention to receive the COVID-19 vaccine scale based on the health belief model has been shown in Figure 1.
Flowchart of psychometric procedures.
Development of the Items Based on the Domains of HBM
Questionnaire items were designed based on the constructs of the HBM using text review.9,12,17,18,32 Ten experts including an epidemiologist, infectious disease specialist, health education and health promotion, nurse, and community medicine were involved in the design of the questionnaire. The collected items were evaluated by experts in terms of the degree of compliance with the purpose of the study and fit with the substructures of the HBM model. In the initial screening by experts, 35 items were extracted. After removing duplicate questions that were repeated in different articles, the number of questions reached 19 questions. This questionnaire included 5 dimensions of the HBM: Perceived threat (susceptibility and severity) which is the combining of two subscales of susceptibility and severity (5 items), perceived benefits (3 items), perceived barriers (5 items), perceived self-efficacy(2 items), and cues to action (4 items). Intention to receive the vaccine was assessed with a question in three grades: “Acceptance of the vaccine, resistance to receiving the vaccine, and hesitancy about receiving the vaccine.” The questions were graded on 4 Likert scales. The questions of the perceived barrier domains were inversely and the rest of the domains were directly scored. The total scores of the questionnaire ranged from 19 to 76.
Assessment of Psychometric Properties
Adaptation Procedures (face validity and content validity)
There is not any guideline to select the panelist of face validity like content validity. 33 Based on experience, the author suggests 10 to 12 experts can give enough good recommendations. In the current study, the qualitative face validity of the questions was checked with 10 participants in terms of difficulty level, appropriateness, or ambiguity. For quantitative face validity, first, for each of the questionnaire expressions, the 5-point Likert scale is quite important (score 5) to not at all important (score 1). Then, 15 participants were asked to review and grade each of the phrases based on their experiences (quantitative face validity). Questions with an item impact index greater than 1.5 were identified and retained as appropriate for subsequent analysis. 34
The content of the questionnaire was validated both quantitatively and qualitatively. To evaluate the validity of qualitative content, a questionnaire was given to 10 experts (epidemiologist, infectious disease specialist, health education and health promotion, nurse, and community medicine). Experts were asked to submit written comments on the content in terms of grammar, and the use of appropriate phrases in the items. After receiving qualitative feedback from experts and correcting comments, a quantitative review of content validity is a complementary method in content validity to ensure that the most important and correct content is selected and tool questions are best designed to measure content designed. Quantitative content validity was assessed by calculating the Content Validity Ratio (CVR) and the Content Validity Index (CVI) for items. The maximum acceptable value for the content validity ratio based on the Lawshe table is 0.62 33 and a CVI score higher than 0.79 was considered appropriate.
Construct validity
To evaluate the validity of the structure and determine the dimensions of the questionnaire, exploratory factor analysis was performed using SPSS software version 16. Principal Component Analysis was performed for hidden variables with varimax rotation and eigenvalue above 1 and a cut-off point of 0.5. The factor load of each question in the factor matrix and the rotated matrix was considered at least 0.3. The sample size at this stage was 1227 people. The KMO test and the Bartlett test (BT) were used to assess the suitability of the sample for factor analysis and the Scree plot to determine the number of constituents of the questionnaire.
Confirmatory factor analysis was used to confirm the number of factors and their relationship with items. For this purpose, the factors extracted by exploratory factor analysis were evaluated using confirmatory factor analysis (CFA) and goodness-of-fit index on 400 samples. The goodness-of-fit index in the present study included the Confirmatory Fit Index (CFI), Good Fit Index (GFI), and Incremental Fit Index (IFI) and the acceptable level of these indices was considered more than 0.9. Also, the Adjusted Goodness of Fit Index (AGFI) with an acceptable level of more than 0.80, the root mean square error index of estimation (RMSEA) with an acceptable level of less than 0.08, and normal or relative chi-square with a level of less than 3 was considered acceptable. 35
Reliability and Stability of the Questionnaire
In this study, to determine the reliability, Cronbach’s alpha coefficient and also the intra-class correlation coefficient was used by test re-testing 15 eligible individuals in two stages with an interval of two weeks completing the questionnaire. Then the intragroup correlation or ICC coefficient was calculated. In designing and evaluating the psychometrics of this instrument, the steps and analyses proposed by the COSMIN checklist were considered. 36
Data Analysis
Data were analyzed using IBM SPSS Amos, SPSS software version 16. Descriptive statistics indicators were used to describe the data. Confirmatory and exploratory factor analysis was used for construct validity.
Results
Baseline Data
Table 1 shows the demographic characteristics of the participants (n = 1227). The results showed that the highest percentage of participants in the study were in the age group of 26 to 35 years (39.8%), female gender (57.1%), and those employed in the hospital (52.5%) (Table 1).
Frequency Distribution and Percentage of Demographic Characteristics of Participants (N = 1227).
Psychometric Properties
In this study, the face validity and content validity of the questionnaire were done in two qualitative and quantitative approaches. In qualitative face validity, all questions fit the objectives of the research. For people with a diploma or higher, it was easy and the questions were not ambiguous.
The quantitative face validity results showed that all items had an impact score greater than 1.5 and they were considered important by the target group.
In quantitative content validity, the results showed that since the CVR numerical value of all questions was greater than the number of the Lawshe table (0.62), the content validity of all questions was confirmed. Thus, the existence of all questions with an acceptable statistical significance level in this tool was essential. Also, all items had a CVI score higher than 0.79, so they were considered appropriate.
In qualitative content validity, the feedback of experts showed the content of the questionnaire was valid to measure intention to receive the COVID-19 vaccine based on HBM model structures in health staff performed.
Since the impact score, content validity ratio, and content validity index of all items were appropriate, the research team did not remove any items from the tool.
In the study of construct validity and determining the dimensions of the questionnaire, the results of exploratory factor analysis showed that the KMO and BT tests were 0.875, 7767.480, and P = .001, respectively. The KMO sampling index in this model was above 0.7, which indicates that the data are sufficient for analysis, and the BT test was significant, indicating that there is sufficient correlation between the variables to analyze the factor.
The Scree plot confirms the existence of five factors visually. This graph shows that the eigenvalues of the 5 factors were higher than one, and this confirms that the 5 extracted factors are appropriate (Figure 2). The variables entered in the analysis are loaded on these 5 factors, which together explain 63.93% of the variance.
Gravel diagram of exploratory factor analysis of Intention to receive COVID-19 vaccine questionnaire based on health belief model.
The first factor consisted of 4 questions, the second factor consisted of 5 questions, the third factor consisted of 3 questions, the fourth factor consisted of 5 questions, and the fifth factor consisted of 2 questions. Each factor was named based on the extracted content as guided action, perceived sensitivity and intensity, perceived benefits, perceived barriers, and perceived self-efficacy, respectively. The Health Belief Model Structures Questionnaire was approved with 19 questions (Table 2), and by adding a behavioral question, the final questionnaire became a total of 20 questions.
Factor Load Values of 5 Factors Extracted From the Questionnaire Based on the HBM Using the Varimax Rotation (N = 1227).
The results of confirmatory factor analysis showed that the GFI was at an acceptable level (χ2/df = 2.782; df = 134; P < .001; CFI = 0.902; GFI = 0.914; IFI = 0.904; AGFI = 0.877 RMSEA = 0.067). The schematic view of the model with factor loads is shown in Figure 3.
Confirmatory analysis and the final model of the intention to receive the vaccine using the health belief model (N = 400).
In this study, the internal consistency coefficient of the instrument was determined by calculating Cronbach’s alpha coefficient. For this purpose, 30 questionnaires were distributed among the research units. Cronbach’s alpha coefficient of the whole tool was calculated to be 0.82. Cronbach’s alpha coefficient of domains and item by item is listed in Table 3.
Cronbach’s Alpha Coefficient of Extracted Factors and Items of Intention to Receive COVID-19 Vaccine Questionnaire Based on Health Belief Model Constructs.
To determine the stability of the questionnaire in the reproducibility dimension, the interclass correlation coefficient (ICC) was calculated. In this part of the study, 20 research units completed the final questionnaire twice in two weeks. The results of the intra-class correlation coefficient of all items were 0.91.
In addition, the relationship between each item and its structure was examined using the Spearman correlation coefficient. All items in each structure had the most relationship with their structure.
Discussion
The results of exploratory factor analysis showed that a 5-factor structure (perceived sensitivity and severity, perceived benefits, perceived barriers, guidance for action, and perceived self-efficacy) was used to predict the intention to receive the COVID-19 vaccine in this sample of health workers following structures of the health belief model. The findings of the study showed that based on the method of maximum likelihood and varimax rotation, 5 known factors explain 63.93 of the variances of behavior. Accordingly, this tool seems comprehensive in terms of explaining the intention to receive COVID-19 vaccination by health workers. Also, in this study, the GFI obtained from the confirmatory factor analysis was at an acceptable level to confirm the model.
The high correlation of each item indicates that the item was effective and sufficient to measure the behavior and confirms the independence of the structures to measure the intended concept. The overall Cronbach’s alpha coefficients and all components of scales except perceived self-efficacy were high and appropriate range. Based on the literature review, the present questionnaire is the first standard questionnaire designed to determine the intention to receive COVID-19 vaccination based on the structures of the health belief model in the population of health workers. However, some studies, which have been limited to determining the intention to receive the COVID-19 vaccine in health workers, it is not based on the model, or all the design steps and psychometric properties of the instruments have not been studied.37,38
Limited studies have been performed to evaluate the intention to receive the COVID-19 vaccine in the general population. In this regard, Shmueli 9 in 2021 examined the intention to receive the COVID-19 vaccine based on the structures of the health belief model in the general population with 11 questions in 5 factors. Questionnaire constructs related to influenza vaccination used for COVID-19. In Shmueli’s study, the questionnaire had good reliability which was consistent with the results of the present study. In another study, Hossain et al 11 in Bangladesh 2021 examined the intention to receive the COVID-19 vaccine with 16 questions in 5 structures of the health belief model. The steps of questionnaire design and psychometrics were not mentioned in the article. Also, only two of the structures had good reliability. In the study of Wong et al 8 in Hong Kong, a behavioral intention questionnaire of cancer patients was used. Since the aim of the study was to accept the COVID-19 vaccine, the validity and reliability of the questionnaire were not re-evaluated. The use of HBM constructs as an important predictor in receiving other vaccines, including influenza vaccine, 39 and papillomavirus vaccine 40 had a good performance, which is in line with the results of the present study and shows the structure of the Health belief models in getting COVID-19 vaccine are just as effective as other vaccines.
The main goal of public health is to protect and improve people’s health and changing people’s behavior is a key element to achieving this goal. 41 The role of individuals’ beliefs and attitudes in social cognitive theories has also been emphasized. 16 Intention to do behavior is one of the important predictors of real behavior. 42 However, according to studies, although a person may intend to behave in a certain way, the intention does not always turn into actual behavior.43,44 The vaccination program is currently considered to be the most effective strategy against the COVID-19 outbreak 45 and identifying the attitudes and beliefs of individuals in this regard, planning and designing interventions to reduce the non-acceptance or receipt of vaccines is one of the most important public health issues. 46 The implications of the health belief model in this study include perceived sensitivity and severity (a person’s perception of the risk of a disease and a person’s perception of the consequences of a disease), also known as a perceived threat, perceived benefits (as a person’s awareness regarding the benefits of a recommended health protection behavior), perceived barriers (understanding the factors that prevent or make it difficult to perform such a health protection behavior), perceived self-efficacy (belief in one’s ability to perform the recommended behavior), and Cues to action. 16 Awareness of these attitudes and beliefs under these headings leads to the design of realistic interventions that provide an optimal solution.
Strengths and Limitations
This study has several strengths. One of the strengths of studying is the high sample size with equal sex categories and high diversity of job positions and the use of the HBM in data collecting. The other is construct validity using exploratory and confirmatory factor analysis approaches.
The present study had some limitations. One of the major limitations was the concern about the generalization of findings for the general population because the designed scale applies to healthcare workers. At the time of setting up this study, the COVID-19 vaccines were still in the primary stage of development. As additional information about the effectiveness and safety of COVID-19 vaccinations becomes available, as well as the availability of various vaccines, participants’ intentions toward vaccination may change. Because culture and social environment may influence healthcare workers’ attitudes toward obtaining the vaccine, this scale should be evaluated in other cultures.
Implications and Future Research Needs
Healthcare workers (HCWs) are an important target group for the COVID-19 vaccine. They are prone to COVID-19 infection first and foremost. On the other hand, vaccination beliefs are one of the most significant barriers to vaccine acceptance and herd immunity, especially when it comes to safeguarding the most vulnerable populations.47-49 Immunization is an important public-health behavior, and the development of an effective and safe COVID-19 vaccine is predicted to minimize COVID-19-related morbidity and mortality. As a result, it’s critical to identify beliefs about COVID-19 vaccination. The HBM is frequently utilized to acquire accurate insights into people’s health behaviors, and it also provides a model for diagnosing vaccination uptake beliefs and attitudes. It has been utilized in numerous past vaccination studies.10,22 As a result, policymakers would be able to create appropriate strategies to improve vaccination acceptance rates based on the survey results with this scale, especially in the event of an outbreak. This valid and reliable questionnaire is recommended for use in a variety of healthcare settings. Given the current pandemic situation, by identifying hesitant people it is recommended that be provided as much information as possible on the benefits and hazards of the subject of their decision, as well as an accurate outline of the risk factors. As a result, future research should focus on social and cultural components that may influence vaccine intention but are not included in the assumptions of the theory of health belief.
Conclusion
It can be concluded that the instrument designed in the preliminary stage of psychometrics properties to determine the intention to receive the COVID-19 vaccine in the research community of health workers had good validity and reliability indicators. Also, the constructs of the health belief model well explain the determinants of the intention to receive the COVID-19 vaccine at the individual level.
Footnotes
Acknowledgements
We would like to thank the Clinical Research Development Center of Ayatollah Mousavi Hospital, Zanjan University of Medical Sciences for their collaboration.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This article was part of a national project and funded by UNICEF and it was approved by the Research Deputy of Zanjan University of Medical Sciences, Iran, with the approval number (The code “ A-12-179-47”).
