Development and validation of the knowledge and attitude regarding childhood vaccination (KACV) questionnaire among healthcare workers: the Malay version

ABSTRACT

Health care workers play an important role in supporting childhood vaccination as they are the most trusted source of vaccine-related information for parents. However, there is limited validated tools to measure their knowledge and attitude on childhood vaccination. This study aims to develop and validate knowledge and attitude regarding childhood vaccination (KACV) questionnaire among healthcare workers. The questionnaire was developed based on literature reviews and underwent a sequential validation process, including content, face validity and exploratory factor analysis. However, the attitude section is unidimensional and has undergone reliability analysis only. The preliminary knowledge questionnaire contains 33 items and the attitude questionnaire consists of 17 items. The preliminary KACV showed a high item Content Validity Index and Face Validity Index. The final questionnaire consists of 10 items for knowledge and 15 items for attitude. The Cronbach alpha for the knowledge and attitude section were 0.896 and 0.861, respectively. KACV is a valid and reliable tool to measure healthcare workers’ knowledge and attitude on childhood vaccination.

KEYWORDS:

• word
• childhood vaccination
• knowledge
• attitude
• immunization
• healthcare worker
• validation
• development

Introduction

A vaccine is the most effective intervention to prevent infectious diseases worldwide and extend life expectancy. Recently, there are increasing attention given to ‘vaccine hesitancy,’ a term used to describe individuals who hold varying degrees of indecision about specific vaccines or vaccination in general.¹ These individuals may refuse certain vaccines, delay vaccines or accept vaccines but are unsure of doing so.¹ Vaccine hesitancy has become an important issue because it has the potential to impact vaccine coverage. The World Health Organization has declared that vaccine hesitancy is one of the global health threats in 2019. However, the information about this issue in middle and low-income countries is limited. This issue was a serious trend globally including in the United States of America. It has contributed to lower rates of childhood vaccination and outbreaks of vaccine-preventable diseases such as measles, pertussis and mumps.^2,3

A study conducted in the United States (US) in 2019 reported that 1 in 15 parents was hesitant about routine childhood vaccination and more than one in four about influenza vaccination.² A review conducted in 2016 that evaluates the association between vaccine delay, refusal and the epidemiology of measles and pertussis with US outbreaks reported that of the 970 measles cases, 574 cases were unvaccinated.³ They also concluded that the trend of vaccine-hesitant was associated with an increased risk for measles among people who refuse vaccines and among fully vaccinated.³ The issue of vaccine-hesitant is not only seen in developed countries but also involves developing countries. WHO adopted the Global Vaccine Action Plan (GVAP) 2011–2020 in 2012 to extend diphtheria, tetanus and pertussis (DPT) vaccination to 90% in every country. However, the South Asia countries lag behind both this coverage and equity goal.⁴ More than four million children under 1-year-old have not received the third dose of the DPT vaccine in Southeast Asia countries.⁴ Despite improved childhood vaccination coverage in most countries since the year 2000, certain countries in Southeast Asia have begun to see reducing trends.⁴ For example, Indonesia has reported that the coverage of childhood vaccination for children below 12 years old in 2018 is 57.9% and a reducing trend is seen since 2014.⁵ There are also upward trends of this issue in Malaysia, resulting in the increasing number of parents who did not vaccinate their children. Statistics showed 637 cases in 2013 and 1,603 cases in 2016.⁶ Since 2016, Malaysia had recorded several deaths among children from diphtheria and the first polio case after 27 years.

Research has reported that one of the barriers that contribute to poor vaccine uptake is vaccine-hesitant parents. Their concerns include low perceived severity of illness, lack of knowledge, media influence, beliefs, perceived adverse reaction of vaccines and overcrowding of immunization schedule.^5,7 As the population began to urbanize and be educated in these middle-income countries, the vaccine-hesitant problem began to root. It created serious challenges to the vaccination coverage. Parents are more likely to be exposed to inaccurate and false information from the media.² A study conducted in Malaysia in 2017 highlighted that those pregnant women with first pregnancy and unemployed parents are the characteristics of the vaccine-hesitant group. They obtained information from the internet.⁸

Healthcare workers (HCW) are considered the most reliable source of information on vaccines. They are in the best position to understand hesitancy issues among patients, respond to their worries and concerns, and find ways to explain to them the benefits of vaccination. However, more and more studies now show that healthcare workers themselves, including those who provide vaccination to patients, give wrong information or even advise patients to prevent taking vaccines.⁹ Vaccine hesitant HCW can have a powerful influence and contribute to vaccine hesitancy among the general population.⁹

A study in France in 2017 reported that almost all general practitioners (GPs) who had not had their children vaccinated with a specific vaccine did not recommend it to their patients, and more than 50% of them who had their children vaccinated did not systematically recommend the same vaccines for their patients.¹⁰ More than half of these GPs had discordances in their practices for their children and their vaccination recommendations for their patients.¹⁰ A similar finding was noted by Picchio et al. 2019 in Barcelona among primary healthcare workers involved in the administration of childhood vaccination. They disclosed that about 25% of these workers have doubts about at least one vaccine.¹¹ They reiterate a lack of trust in pharmaceutical companies and government, lack of knowledge and belief in certain myths held by the vaccine-hesitant parents.¹¹

A systematic review of global literature published in 2018 on midwives’ attitudes, beliefs, and concerns about childhood vaccination revealed that although a majority supported vaccination, a minority expressed reservation on the justification of vaccination and considered measles a benign disease that does not warrant vaccination against them.¹² These studies highlight a very serious issue that is the healthcare provider can be vaccine-hesitant themselves. Research to identify and understand these healthcare workers’ attitude and practice is crucial to ensure the success of childhood vaccination programmes.

Although there was much research conducted on healthcare workers’ knowledge, attitude and practice on childhood vaccination, most of these studies were conducted in western countries and there is a lack of validated tools. Currently, there is no validated instrument to measure the knowledge and attitude of HCW on childhood vaccination in Malaysia. Given the current situation, there is a need for a validated instrument to assess this problem so that intervention can be done to overcome the issues of inadequate knowledge or misconception of childhood vaccination among healthcare workers in Malaysia. This study aims to develop and validate knowledge and attitude regarding childhood vaccination (KACV) questionnaire among healthcare workers.

Methods

The development and validation of the KACV questionnaire were performed in two stages. The first stage was questionnaire development, and the second stage comprised psychometric validation using Exploratory Factor Analysis (EFA).

Stage 1: questionnaire development

The knowledge and attitude regarding childhood vaccination (KACV) questionnaire was developed based on the Health Belief Model (HBM)¹³ and previous literature.^14–18 It is a self-administered questionnaire developed in Malay, the official national language, for easy administration. This newly drafted knowledge section was divided into four domains which consist of 33 items. The domains were advantages of vaccination (10 items), side effects/adverse reactions (8 items), methods, site, or types of vaccination (7 items), and myths of vaccination (10 items). The knowledge item was assigned to a score of 3 for a correct response, 2 for a not sure response, and 1 for a wrong response. However, 15 items (items 12–16, 19, 24–30, 32, 33), were assigned to reverse scoring.

The concepts involved in the HBM that include Perceived Susceptibility, Perceived Severity, Perceived Benefits, Perceived Barriers, Cues to Action, and Self-Efficacy were used to develop the attitude section questionnaire.¹³ The attitude section was unidimensional and consisted of 17 items. The questions were about disease severity and symptoms, disease susceptibility, vaccine effectiveness, vaccine safety, key immunization beliefs, cues of action regarding social/peers influence, and main source of information. A 5-point Likert scale is used, and responses are assigned to a score of 5 for ‘Strongly agree,’ 4 for ‘Agree,’ 3 for ‘Neutral,’ 2 for ‘Disagree’ and 1 for ‘Strongly disagree.’ For ten items (2, 4–6, 8, 10, 12, 14, 15, 17), reverse scoring is applied.

Content and face validity

Content validity measures the extent of the instrument corresponds to or reflects the specific construct for a particular assessment intention.¹⁹ Setting up the content validity is essential to guide the validity of evaluation questionnaires and should be regarded as a high priority in developing an instrument.²⁰ Content validity assesses the degree to which items‏ of‏ an instrument sufficiently represent the content domain and the extent of the selected sample is a comprehensive sample of the content.²¹ Content validity provides the preliminary evidence on the construct validity‏, information on the representativeness and clarity of items and help improve an instrument through achieving recommendations from‏ an expert panel.²² There are few methods used to assess the content validity of a questionnaire. This study utilized a method known as content validity index (CVI), the most widely used method.

The CVI can be calculated using item-CVI (I-CVI) and scale-CVI (S-CVI). In this study, the content validation was assess based on relevance. According to Shaiful (2019), the rating scale of relevance (5–8) has been used for scoring individual items. In this study, we invited six experts to rate each item of the KACV based on a 5-point rating scale from 1 for ‘not relevant to 5 for ‘highly relevant.’ Before CVI calculation, the relevance rating was recorded as 1 (if the item was rated 4 or 5) or 0 (if the item was rated < than 4). Then the I-CVI is calculated based on the number of experts giving a rating of 4–5 for each item divided by the total number of experts.¹⁹ The recommended I-CVI for six experts is at least 0.83.¹⁹ If the I-CVI > 0.79, the item is relevant; between 0.70 and 0.79, the item needs revisions; and if the I-CVI value is below 0.70, the item is eliminated.²² Polit et al 2006 concluded that this measurement ease the computation, understandability, focus on agreement of relevance rather than agreement per se, focus on consensus rather than consistency, and provision of both item and scale information compared to alternative indexes.²³ This measurement also has been used in the development of other instruments such as measuring patient communication and facilitators, barriers and preferences to exercise in people with osteoporosis.^20,22 For S-CVI, our study utilized the Average CVI (S-CVI/Ave).¹⁹ S-CVI/Ave is calculated by taking the sum of the I-CVIs divided by the total number of items, and the value of ≥ 0.83 has an acceptable cutoff score.^19,24

The content validity of the questionnaire was conducted with a panel of six experts which consisted of family medicine specialists, pediatricians, and community medicine specialists. The content validity was established through qualitative and quantitative approaches. The panel rated the items for relevancy (how important the item is) using a 5-point Likert scale (ranging from not relevant to very relevant). The panel also made a recommendation for the modifications of the items or suggested new items for the questionnaire. Modifications were made to the drafted KACV after the content validation.

Then, the face validity of the KACV questionnaire was conducted on ten HCW from Universiti Sains Malaysia Hospital in printed form to evaluate the understanding toward the comprehension of the questionnaire and determine how meaningful the items were to target participants. Instrument review by a sample of subjects that represents the target population is another pertinent component of instrument development.²² These individuals are asked to review instrument items because of their familiarity with the construct through direct personal experience.²² These subjects cannot be replaced by professionals, expert or statistician and their interpretation of the item will determine the accuracy of the instrument. The concept of face validity is also known as the response process of validity as the term reflect the thought processes of target users of an instrument and can be quantified as Face Validity Index (FVI).^25,26 According to Cook and Beck 2006, the response process validity can be represented by FVI and several recent studies have used this method to support the validity of an assessment tool.^27,28 In this study, we utilized the method to calculate the FVI based on the recommendation by Yusoff M 2019.²⁵ The HCWs were requested to rate the items based on clarity and comprehension (5-point Likert scale). Likert scores of 4–5 were categorized as very clear and understandable and was recorded as 1. The other scales were categorized as 0. The item-face validity index (I-FVI) and scale-face validity index (S-FVI/Ave) were calculated. I-FVI is calculated as the number of HCW giving a rating of 4–5 for each item divided by the total number of HCW, and S-FVI/Ave is calculated based on the sum of the I-FVIs divided by the total number of HCW (n = 10). The recommended FVI for 10 participants is at least 0.83.²⁵ They also were asked to comment on the items. Their various responses and understanding regarding the questions and vagueness were assessed. A revised and finalized version of the questionnaire was produced from the face validity used in the second stage study, psychometric analysis using EFA.

The questionnaire administered to the participants consisted of four sections: (1) sociodemographic, (2) working experience and cues for action, (3) knowledge on childhood vaccination, (4) attitude on childhood vaccination. Sociodemographic data include age, sex, religion, education level, marital status, and the number of children. The working experience includes years of working experience, whether jobs characteristic has direct contact with patients, experience in pediatric department/clinic, experience in giving immunization to children, history of Continuous Medical Education or courses regarding childhood vaccination in the past one year, own child or family members with adverse reactions to childhood vaccination, the main source of reference for information regarding children vaccination and experience in taking influenza or pneumococcal vaccination.

Stage 2: psychometric validation study

A cross-sectional study was conducted in the School of Health Sciences, Universiti Sains Malaysia. The sample size was calculated based on the sample size for EFA using a sample to a variable ratio (N: p Ratio where N refers to the number of participants and P refers to the number of variables or items) recommended for questionnaire validation studies. The rule of thumb is based on N: p range anywhere from 3: 1 to 20: 1.²⁹ For this study, the ratio of 3:1 (3 participants per item) and a 10% non-response rate will be applied, yielding 110 samples.

The inclusion criteria for this study included all types of professions of workers that have been involved in health discipline such as nursing, bio medics, radiology, dietitian, occupational therapy, audiology, speech therapy, physiotherapy, and nutrition (lecturers and postgraduate students), either permanent and contract workers, understand Malay language and have USM e-mail. During the survey, those on long leave (maternity leave/sabbatical leave) were excluded from the study.

One of the research team members advertised and circulated the survey link to the staff and postgraduate students. The questionnaire was hosted via Google forms and was exported to Excel spreadsheets for analysis. The participants were informed that their participation was voluntary, and before starting the survey, the consent of the persons was obtained via Google form. Approximately 20 minutes is required for each participant to complete a set of questionnaires.

Statistical analysis

Data entry and statistical analysis were performed using IBM SPSS Statistic version 26.0. (SPSS Inc., Chicago, IL, USA, (2019)). The data entered were checked for outliers and missing values. Descriptive statistics were used to describe responses to the items in the questionnaire where floor and ceiling effects were noted. The EFA was conducted only on the knowledge domain of the KACV but not on the attitude domain. It is because the attitude consists of only one construct. However, both the knowledge and attitude domains of KACV were analyzed for internal consistency reliability using Cronbach’s alpha coefficient.

Statistical significance of the Bartlett test of sphericity (<0.05) was used to indicate if there were sufficient correlations among the items.³⁰ Fulfilling this assumption indicated that the data were appropriate for factor analysis to examine the entire correlation matrix. Meanwhile, the measure of sampling adequacy was obtained based on the Kaiser-Meiyer-Olkin (KMO) value. A KMO value of at least 0.5 and significant Bartlett’s test of sphericity with a p-value of < 0.05 would mean suitability to proceed to factor analysis.³⁰ Principal axis factoring with promax rotation extraction (Eigenvalue ≥ 1) was applied to explore the structure within the data by providing a basis for removing redundancy or unnecessary items. Principal factor analysis with Promax rotation was used.

The items were retained for further analysis if they have the ideal communality value of 0.3 and higher to indicate convergent validity³¹ and have factor loadings of 0.3 and higher.^30,32 This method was used in another study about validation of instruments such as Farsi version of Wijma delivery expectancy questionnaire.³³ To measure the quality of the items proposed, three criteria were analyzed: item communalities, cross-loaded factor, and factor loadings. The KACV reliability was measured through internal consistency (IC) analysis and Cronbach’s alpha coefficient. The questionnaire items were considered to represent a measure of good internal consistency if the total of Cronbach’s alpha value was more than 0.7.³⁴

Ethical considerations

Ethical approval was obtained from the Human Ethics Research Committee, Universiti Sains Malaysia (Approval No. USM/JEPeM/20050250). An online consent via google form was taken from the participants as verification to participate in this study. All information gathered from this study was strictly confidential and only to be used in this study.

Results

Content validity

The I-CVI relevancy for KACV ranges from 0.50 to 1 (Table 1). The S-CVI/Ave for both the knowledge and attitude domain is 0.92. In the knowledge section (33 items), 29 items had I-CVI ≥ 0.83, and in the attitude section (17 items), 15 items had I-CVI ≥ 0.83. A total of 10 items were removed, and one item was added. Four items were removed because the panel thought they were not suitable to be asked. After all, Malaysia is implementing a new vaccination schedule. The final KACV questionnaire consists of 28 items for knowledge and 15 items for the attitude domain.

Table 1. Content validation for KACV

Item/raters	R1	R2	R3	R4	R5	R6	I-CVI (Relevancy)
Knowledge
Q1	1	1	1	0	1	1	0.83
Q2	1	1	1	1	1	1	1
Q3	1	1	1	1	1	1	1
Q4	1	1	1	1	1	1	1
Q5	1	1	1	1	1	1	1
Q6	1	0	1	1	1	1	0.83
Q7	1	1	1	1	0	1	0.83
Q8	1	1	1	1	1	1	1
Q9	1	1	1	1	1	1	1
Q10	1	1	0	0	1	0	0.50
Q11	1	1	1	1	1	1	1
Q12	1	1	1	1	1	1	1
Q13	1	1	1	1	1	1	1
Q14	1	1	1	1	1	1	1
Q15	1	1	1	1	1	1	1
Q16	1	1	1	1	1	1	1
Q17	1	1	1	1	1	1	1
Q18	1	1	0	1	1	0	0.67
Q19	1	1	0	1	1	0	0.67
Q20	1	1	1	1	1	1	1
Q21	1	1	1	1	1	1	1
Q22	1	0	1	1	1	1	0.83
Q23	1	1	1	1	1	1	1
Q24	1	1	1	1	1	1	1
Q25	1	1	1	1	1	1	1
Q26	1	1	1	1	1	1	1
Q27	1	1	1	1	1	1	1
Q28	1	1	1	0	1	1	0.83
Q29	1	0	0	1	1	0	0.5
Q30	1	1	1	1	1	1	1
Q31	1	1	1	1	1	1	1
Q32	1	1	1	1	1	1	1
Q33	1	1	1	1	1	1	1
Attitude
Q1	1	1	1	1	1	1	1
Q2	1	1	1	1	1	1	1
Q3	1	1	1	1	1	1	1
Q4	1	1	1	1	1	1	1
Q5	1	1	1	1	1	1	1
Q6	1	1	1	1	1	1	1
Q7	1	1	1	1	1	1	1
Q8	1	1	1	1	1	1	1
Q9	1	0	1	1	1	1	0.83
Q10	0	0	1	1	1	1	0.67
Q11	1	1	1	1	1	1	1
Q12	1	1	1	1	1	1	1
Q13	0	1	0	1	1	0	0.50
Q14	1	0	1	1	1	1	0.83
Q15	1	0	1	1	1	1	0.83
Q16	1	1	1	1	1	1	1
Q17	1	1	1	1	1	1	1

r – rater

I-CVI – Item Content Validity Index

Face validity

The I-FVI for the knowledge section range from 0.7–1 (Table 2). Only one item had I-FVI 0.7, and the rest had I-FVI more than 0.9. For the attitude section, all items had I-FVI of more than 0.83 (Table 2). The S-FVI/Ave for the knowledge and attitude domains were 0.97 and 0.92, respectively. Modifications were made to few items based on the suggestions by the participants.

Table 2. Face validation for KACV

Item/raters	R1	R2	R3	R4	R5	R6	R7	R8	R9	R10	I-FVI
Knowledge
Q1	1	1	1	1	1	1	1	1	1	1	1
Q2	1	1	1	1	1	1	1	1	1	1	1
Q3	1	1	1	1	1	1	1	1	1	1	1
Q4	1	1	1	1	1	1	1	1	1	1	1
Q5	1	1	1	1	1	1	1	1	1	1	1
Q6	1	1	1	1	1	1	1	1	0	1	0.9
Q7	1	1	1	1	1	1	1	1	1	1	1
Q8	1	1	1	1	1	1	0	1	1	1	0.9
Q9	1	1	1	1	1	1	1	1	1	1	1
Q10	1	1	1	1	1	1	1	1	1	1	1
Q11	1	1	1	1	1	1	1	1	1	1	1
Q12	1	1	1	1	1	1	1	1	1	1	1
Q13	1	1	1	1	1	1	1	1	1	1	1
Q14	1	1	1	1	1	1	1	1	1	1	1
Q15	1	1	1	1	1	1	1	1	1	1	1
Q16	1	1	1	1	1	1	1	1	1	1	1
Q17	1	1	1	1	1	1	1	1	1	1	1
Q18	1	1	1	1	1	1	1	1	1	1	1
Q19	1	1	1	1	1	1	1	1	1	1	1
Q20	1	1	1	1	1	0	1	1	1	1	0.9
Q21	1	1	1	1	1	0	1	1	1	1	0.9
Q22	1	1	1	1	1	1	1	1	1	1	1
Q23	1	1	1	1	1	1	1	1	1	1	1
Q24	1	1	1	1	1	0	1	1	1	1	0.9
Q25	1	1	1	1	1	0	1	1	1	1	0.9
Q26	1	1	1	1	1	1	1	1	1	1	1
Q27	1	1	1	1	1	1	1	1	1	1	1
Q28	0	1	1	1	0	0	1	1	1	1	0.7
Attitude
Q1	1	1	1	1	1	1	1	1	1	1	1
Q2	1	1	1	1	1	1	1	1	1	1	1
Q3	1	1	1	1	1	1	1	1	1	1	1
Q4	0	0	1	1	1	1	1	1	1	1	0.8
Q5	1	1	1	1	0	1	1	1	1	1	0.9
Q6	0	1	1	1	1	1	1	1	1	1	0.9
Q7	1	1	1	1	1	1	1	1	1	1	1
Q8	1	1	1	1	1	1	1	1	1	1	1
Q9	1	0	1	1	1	1	1	1	0	1	0.8
Q10	1	1	0	1	0	1	1	1	1	1	0.8
Q11	1	1	1	1	1	1	0	1	1	1	0.9
Q12	0	1	1	1	1	0	1	1	1	1	0.8
Q13	1	1	1	1	1	0	1	1	1	1	0.9
Q14	1	1	1	1	1	1	1	1	1	1	1
Q15	1	1	1	1	1	1	1	1	1	1	1

R – rater

I-FVI – Item Face Validity Index

Psychometric analysis

A total of 114 participants completed the study. The baseline characteristic of the participants was showed in Table 3. The majority were between 31–40 years old (44.7%), Malay (97.4%) and married (83.3%).

Table 3. Baseline socio-demographic data of the participants

Variables	N	%
Age (years)
25–30	12	10.5
31–35	18	15.8
36–40	33	28.9
41–45	20	17.5
46–50	15	13.2
>51	16	14.0
Sex
Female	91	79.8
male	23	20.2
Level of education
Diploma/certificate	59	51.8
Degree	29	25.4
Master	6	5.3
PhD	19	16.7
Ethnicity
Malay	111	97.4
Others	3	2.6
Marital status
Married	95	83.3
Single	19	16.7
Duration of service
1–5 years	18	15.8
6–10 years	26	22.8
11–15 years	18	15.8
16–20 years	25	21.9
21–25 years	16	14.0
26 years and above	11	9.6
Types of occupation
Lecturer	19	16.7
Medical Officer	11	9.6
Science Officer	5	4.4
Management Officer	1	.9
Audiologist	1	.9
Dietitian	3	2.6
Nursing tutor	5	4.4
Lab. Technician	2	1.8
Physiotherapist	1	.9
Medical assistant	11	9.6
Staff Nurse	37	32.5
Community Nurse	16	14.0
Health assistant	2	1.8

Response to items

Six items in the knowledge section (KB1, KB5, KB6, KB7, KB8 and KT18) were removed due to the ceiling effect (percent of respondents answering ‘Yes’ was > 94%). There was no floor effect.

Validation and reliability

The EFA was conducted only to the knowledge section of the KACV. The KMO measure of sampling adequacy was 0.75 and the significance of Bartlett’s test of sphericity was less than 0.001, indicating that the data was suitable to proceed with further factor analysis. Thus, 22 items of the knowledge domain underwent EFA. Parallel analysis suggested a 4-factor model, and EFA was proceeded by fixing the number of factors to four constructs. However, later after the removal of items with low factor loadings (<0.3), the number of constructs was fixed to two based on the eigenvalue greater than one criterion. A total of eight items were removed due to low factor loading (< 0.3). The validity of the 2-factor model was further confirmed by the communalities of each attribute as all the communalities (factor loading) were more than 0.3. The two domains are shown in Table 4. However, because the Cronbach alpha for domain B was <0.7, the research team decided to remove this domain. The Cronbach alpha for the final questionnaire was 0.896 and 0.763 for the knowledge and attitude domain, respectively.

Table 4. EFA and Reliability of Knowledge section of KACV

	Factor loading	Cronbach alpha
Domain A
Vaksin MMR (Measles, Mumps, Rubella) diberikan kepada kanak-kanak bagi mencegah penyakit campak, beguk dan rubella. The MMR vaccine (Measles, Mumps, Rubella) was given to children to prevent measles, mumps and rubella	0.495	0.896
Kesan sampingan vaksin MMR (Measles, Mumps, Rubella) boleh mengancam nyawa. Side effects of the MMR vaccine (Measles, Mumps, Rubella) can be life-threatening.	.482
Kesan sampingan akibat suntikan vaksin polio boleh menyebabkan lumpuh kaki. Side effects of polio vaccine can cause paralysis of the legs.	.515
Vaksin bagi penyakit campak (Measles) boleh menyebabkan autism. The measles vaccine can cause autism.	.594
Perubatan alternatif seperti homeopati atau herba boleh menggantikan vaksin bagi melindungi daripada penyakit berjangkit. Alternative medicine such as homeopathy or herbs can replace vaccines to protect against infectious diseases.	.518
Pengambilan pelbagai jenis vaksin boleh menjejaskan sistem pertahanan ketahanan badan kanak-kanak Acquisition of various types of vaccines can affect the immune system of children.	.519
Vaksin tidak diperlukan sekiranya kanak-kanak lain di sekelilingnya telah mengambil vaksin. The vaccine is not required if the other children around unvaccinated child were vaccinated.	.811
Vaksin polio tidak diperlukan kerana penyakit polio sudah tidak wujud. The polio vaccine is not needed because polio disease is no longer exists.	.447
Vaksinasi adalah tidak perlu kerana sistem pertahanan badan semula jadi kanak-kanak sudah mencukupi. Vaccination is not necessary because the natural immune system of children is adequate.	.649
Kanak-kanak yang diberikan susu ibu secara eksklusif tidak memerlukan vaksinasi. Children who are breastfed exclusively does not require vaccination.	.787
Domain B
Vaksin BCG (Bacillus-Calmette-Guerin) diberikan kepada bayi baru lahir. The BCG (Bacillus-Calmette-Guerin) vaccine is given to newborns.	.336	0.474
Vaksin Haemophilus Influenza diberikan kepada kanak-kanak di Malaysia. Haemophilus Influenza vaccine is given to children in Malaysia.	.520
Perlindungan sepenuhnya terhadap jangkitan penyakit tidak dapat dicapai jika tidak mematuhi jadual vaksinasi. Full protection against infection cannot be achieved if not adhere to the vaccination schedule.	.310
Pemberian vaksin perlu ditangguhkan sekiranya kanak-kanak mengalami demam dengan suhu badan yang tinggi. Vaccination should be postponed if the child has a fever and high body temperature.	.392

Discussion

Understanding the vaccine hesitancy among healthcare workers especially in Asia countries especially South Asia is pertinent because the coverage of childhood vaccination is still low.³⁵ In 2013, 6.3 million children under five years old died to due infectious diseases which can be prevented through vaccination.³⁵ Education and inequalities on antenatal and child services play an important role in this scenario.³⁶ HCW have been identified as the most reliable and impactful source of information on vaccination for parents and their children.^9,10 Therefore, studies to obtain the knowledge and attitude of the HCW on childhood vaccination is important to tailor interventions of vaccine-hesitant parents.

Recent studies^37–39 on knowledge, attitude and behavior on vaccination have reported that education and socioeconomic status had significant determinants on these attributes. Poor communication and limited communication resources seem to be the important predictors of vaccine acceptance in both developed, developing or underdeveloped countries.³⁹ A systematic review on knowledge, attitude and belief toward compulsory vaccination highlighted that healthcare workers attitude toward mandatory vaccination had a significant impact on parents or patients.³⁹ These studies reiterate that healthcare workers knowledge and attitude contribute to the uptake of the vaccination program. The other issue is regarding the healthcare workers attitude in dealing with parents label as ‘vaccine hesitant’ parents. Philpott et al. 2017 conducted a study to examine the medical students and residents attitudes and behavior intentions toward situations that require discussion on clinical evidence with patients. They reported that the clinicians had negative perceptions and spend less time with the group of vaccine-hesitant parents. This study indicates that the attitude of the healthcare workers in dealing with this problem also plays a pertinent role in addressing the issue of vaccine hesitation.⁴⁰

The initial KACV consists of 33 items for knowledge and 17 items for the attitude section. However, after the sequential validation process, the final version consists of only 10 items for knowledge and 15 items for the attitude section. Validation of the questionnaire is important to ensure that it accurately measures what it aims to and provide quality data for evidence. Although there are many studies done¹⁶ to assess the knowledge and attitude of HCW on vaccination, there is limited information on the validity and reliability of the questionnaire used especially tailored to the culture and language of the population. The KACV questionnaire was developed and validated in the local language, making it suitable and practical for all categories of HCW in Malaysia. This study utilized intensive methods for the development and validation process of the questionnaire which are not utilized previously for knowledge and attitude on childhood vaccination. The uniqueness of KACV questionnaire development is that we used both qualitative and quantitative methods for content and face validity. For example, Awad et al. 2019 conducted a cross-sectional study to assess the knowledge, behavior and practice among the public in Jordan on influenza vaccination.⁴¹ However, the study did not report the results of the development and validation of the instrument used. Most papers did not report indexes of content validity.²⁰ Similarly, Zhao et al 2021 developed a questionnaire based on the Technology Acceptance Model theory to assess knowledge, attitude and practice on influenza vaccination among parents in China.⁴² The study did not report any content or face validity for the questionnaire.⁴² However, we considered using both, and only items with I-CVI score ≥ 0.83 were retained in the questionnaire. This ensures that the items were clear and relevant in measuring knowledge and attitude on childhood vaccination for HCW in Malaysia. Four items were later removed because these items assess on the immunization schedule. Since Malaysia is updating the immunization schedule during the study by adding pneumococcal vaccines, the researchers think that many HCW might not be aware of the changes at that time. One item that assessed the side effect of Polio vaccination was introduced to replace the removed items. Based on the content validity evaluation of the questionnaire, some items were deleted as they were shown to be problematic validity in terms of their relevance in measuring knowledge and attitude of childhood vaccination. We also used an adequate number of experts for the content validation. This method supports the evidence that the items were important and relevant to measure knowledge and attitude of childhood vaccination among HCW.

Face validity conducted among the HCW assessed the clarity of the items from the target user’s point of view. The content expert might have different views of the items’ relevancy and clarity. Using two different groups of reviews ensures content validity while considering the comprehensibility of the items in the questionnaire. All items except one item in the knowledge section had high FVI, indicate that the questionnaire is clear and understandable. This item was later modified to improve its clarity. Overall, KACV benefitted from the content validity and face validity process, where there were substantial changes in the types of items, concept, wording, and overall structure of the questionnaire.

The EFA of the knowledge domain showed that a two-factor structure accounts for 52.7% of the total observed variance, which was what was hypothesized, and factor loadings that were above 0.3. However, the reliability analysis of domain B (Table 4) indicated a low Cronbach’s alpha value, so the researchers decided to remove this domain. Thus, the knowledge section becomes unidimensional. However, the final KACV is a valid and reliable questionnaire to assess HCW knowledge on childhood vaccination.

The final KACV questionnaire on the knowledge section content ten items which include relevant issues about Measles, Mumps, Rubella (MMR) vaccines such as the issue of autism and side effects of vaccination, the need for polio vaccination and the role of alternative therapy to replace vaccination. The KACV did not include the item on influenza and Human papillomavirus (HPV) vaccination. This is because influenza vaccination is not part of the childhood vaccination program which is given free and HPV vaccination is considered vaccination for adolescents in Malaysia. KACV also assess the attitude on mandatory vaccination. This is because mandatory vaccination has been considered as one of the solutions to overcome vaccine-hesitant populations.³⁹

The content of this knowledge section was also similar to the study done by Picchio et al. 2019 in Barcelona.¹¹ The attitude section of KACV comprises the relevant items according to the conceptual framework proposed by Peterson et al. 2016 in the adaptation of the SAGE Working Group model of determinants of vaccine hesitancy for HCW.¹⁸ It includes vaccine or vaccination specific issues such as risk and benefits, vaccination schedule, effectiveness, personal experience, and trust in the health system and provider. The attitude section includes items that are relevant in this era regarding the trust in the vaccine i.e. I believe vaccines are a hidden agenda to benefit drug companies. A similar reaction was observed during the COVID 19 vaccine issues. Perceived risk and barriers to vaccination were also included such as worried about the severe reaction to the vaccination and feel that children are getting too many jabs. These were based on the Health Belief model¹³ and the same construct was used by Zhou et al. 2021 on parental acceptance of influenza vaccination. This aspect of attitude was also used in the study among the GP in France¹⁰ and primary HCW in Barcelona.¹¹ The KACV covered a broad and common topic about childhood vaccination which can be applied in other countries and not specifically for Malaysia. Assessing knowledge and attitudes about childhood vaccination among healthcare workers is important to achieve immunization coverage and reduce vaccine-preventable diseases in our population. Understanding factors affecting knowledge and attitude on childhood vaccination among these groups of HCW may help develop targeted interventions since they are one of the main sources of information for the public. This tool has potential applications in both the research setting and in clinical practice. Thus, further study can assess knowledge or misconception and attitude of childhood vaccination among healthcare workers in Malaysia.

We think this study contribute to the new evidence of validated tools for assessment of knowledge and attitude on childhood vaccination among healthcare workers. The questionnaire items in this study are updated and relevant to address the current issue regarding vaccine hesitation in healthcare workers.

The limitations of this study are that this questionnaire was developed in the Malay language and thus only can be utilized in the population who understand this language. Second, the results showed a lack of variability across Likert scale items. Six items were removed because of ceiling effects in the knowledge section. More than 90% of the respondents answer yes or correct answer in the knowledge section. This suggests that the items were easy for the respondents. Third, the validation study was conducted in a tertiary center. Primary care HCW may give different results.

Acknowledgments

We would like to acknowledge Dr Norsarwany Mohammad, Dr Noraida Ramli, Dr Rosnani Zakaria and Dr Azriani Berahim @ Abdul Rahman for their contribution as expert reviewers in this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website at https://doi.org/10.1080/21645515.2021.1989915

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.