COVID-19 vaccination acceptance among dental students and dental practitioners: A systematic review and meta-analysis.

BACKGROUND: Dental practitioners and dental students are classified as high-risk exposure to COVID-19 due to the nature of dental treatments, but evidence of their acceptance towards COVID-19 vaccination is still scarce. Hence, this systemic review aims to critically appraise and analyse the acceptability of COVID-19 vaccination among dental students and dental practitioners.
MATERIALS AND METHODS: This review was registered in the PROSPERO database (CRD42021286108) based on PRISMA guidelines. Cross-sectional articles on the dental students' and dental practitioners' acceptance towards COVID-19 vaccine published between March 2020 to October 2021 were searched in eight online databases. The Joanna Briggs Institute critical appraisal tool was employed to analyse the risk of bias (RoB) of each article, whereas the Oxford Centre for Evidence-Based Medicine recommendation tool was used to evaluate the level of evidence. Data were analysed using the DerSimonian-Laird random effect model based on a single-arm approach.
RESULTS: Ten studies were included of which three studies focused on dental students and seven studies focused on dental practitioners. Four studies were deemed to exhibit moderate RoB and the remaining showed low RoB. All the studies demonstrated Level 3 evidence. Single-arm meta-analysis revealed that dental practitioners had a high level of vaccination acceptance (81.1%) than dental students (60.5%). A substantial data heterogeneity was observed with the overall I2 ranging from 73.65% and 96.86%. Furthermore, subgroup analysis indicated that dental practitioners from the Middle East and high-income countries showed greater (p < 0.05) acceptance levels, while meta-regression showed that the sample size of each study had no bearing on the degree of data heterogeneity.
CONCLUSIONS: Despite the high degree of acceptance of COVID-19 vaccination among dental practitioners, dental students still demonstrated poor acceptance. These findings highlighted that evidence-based planning with effective approaches is warranted to enhance the knowledge and eradicate vaccination hesitancy, particularly among dental students.

Introduction

A newly identified coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or known as the coronavirus disease 2019 (COVID-19), has been wreaking havoc all over the world since its emergence in Wuhan, China in December 2019 [1]. The World Health Organisation (WHO) labelled the COVID-19 outbreak a "Public Health Emergency of International Concern" on January 30, and later, a global pandemic on March 11, 2020 [2]. Ever since, COVID-19 has inflicted millions of deaths globally, presented the government with an unprecedented challenge in the face of severe economic, fiscal, and social pressures, as well as exerted an incredible impact on every sphere of human life.

Despite the implementation of several lockdowns around the world, the infection was not contained due to the reappearance of new COVID-19 variations that were more infective [3]. Several strains of SARS-CoV-2 have been discovered throughout the pandemic and are categorized into three groups: variants of interest, variants of concern, and variants of high consequence [4]. Delta and Omicron variants are among the mutated strains listed as variants of concern which appeared to spread more swiftly than the initial SARS-CoV-2 strain, leading to an increase in COVID-19 cases [4]. These variants have also been linked to increased hospitalisations, reduced neutralisation by antibodies from a previous infection, and diagnostic detection failures [5, 6]. It was soon realised and agreed that herd immunity was the only way to halt the pandemic as several studies have reported promising antibody responses to these variants after vaccine administration [5, 7]. Many countries have begun mass immunisation campaigns for their entire population to curb the widespread of viruses [8]. However, vaccine acceptance and hesitation remained a major obstacle to achieve herd immunity in all countries. Concerns about the vaccination’s safety and effectiveness, personal and religious beliefs, and political issues were all mentioned as causes for vaccine apprehension [1, 9].

Dental practitioners are among the healthcare workers classified as high-risk of infection during the COVID-19 pandemic due to the nature of their profession and the close proximity of the dental team to the patients [10]. SARS-CoV-2 spreads rapidly through droplets of saliva during various aerosol-generating dental operations, prompting the development of specific guidelines to minimise virus transmission in the clinical setting [10, 11]. Dental practitioners are also responsible to understand the disease and follow stringent protocols to avoid the spread of disease in their workplaces, assuring the safety of both workers and patients. Nevertheless, vaccination remains the ultimate solution to this issue. On the other hand, dental students, who make up a small proportion of the oral healthcare workforce, are at the same risk of COVID-19 infection as dental practitioners due to the nature of their clinical training in the dental faculties [12]. It is conceivable that attitudes in the dental profession reflect sentiments in other sectors, leading to a better understanding of vaccine attitudes and the implementation of strategies to tackle vaccine reluctance [13]. Although it has been documented that conspiracy beliefs and misunderstanding about immunity have limited university students’ acceptance of the COVID-19 vaccine [14], concrete evidence on COVID-19 acceptability among dental students is still warranted. Thus, determining the vaccination acceptance rate of dental students and dental practitioners is critical.

Vaccine hesitancy is defined as the refusal or postponement of vaccination despite the availability of services [15], and the WHO has identified vaccine hesitancy as a global health threat. Several studies have been undertaken around the world to assess the acceptance rate of the COVID-19 vaccine among dental practitioners and dental students, but the results were ambiguous with a wide array ranging from 56% to 86% [12, 16–20]. To the best of the authors’ knowledge, no systematic review has been reported pertaining to the COVID-19 vaccination acceptance among dental students and dental practitioners. Therefore, the present systematic review sought to systematically evaluate the acceptance rate of COVID-19 vaccination among dental students and dental practitioners.

Materials and methods

Protocol and registration

The present review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA) guideline [21], and was registered in the Prospective Register of Systematic Reviews (PROSPERO), National Institute for Health Research (NIHR), University of York, with the registration number (ID: CRD42021286108). The focused question was developed by using the PIOT framework, which includes the Population (P), Indicator (I), Outcome of interest (O), and Time (T).

The PIOT criteria were: (1). Population: dental students and dental practitioners (2). Indicator: COVID-19 vaccine (3). Outcome: Acceptance level (4). Time: during COVID-19 pandemic. Hence, the PIOT question was “What is the level of acceptance of COVID-19 vaccine among dental students and dental practitioners?”. In this context, a dental student is a person who is currently enrolling in a dental programme and attending a recognised dental school on a regular basis. On the other hand, a dental practitioner is a person who is qualified and licenced by the state law to practise dentistry and provide dental treatments within the limits of their licence and certification. This includes dentists, dental specialists, or postgraduate dental students who have acquired a basic dental degree.

Search strategy

Three investigators (JZL, HYL, WFL) independently conducted a primary search for articles published between March 2020 and October 2021 using eight electronic databases: Google Scholar, PubMed, Web of Science, Science Direct, Cochrane Library, EBSCO, LILACS, and Open Grey. The reference lists of pertinent articles from the electronic search were independently evaluated by two other investigators (GSSL, MMS) using a computer software (EndNote X9, Thomson Reuters). The following search terms were used for each database: ‘acceptance’, ‘attitude’, ‘willingness’, ‘reluctance’, ‘hesitancy’, ‘vaccine’, ‘vaccination’, ‘dental’, ‘dentist’, ‘Covid-19’ and ‘pandemic’. The Boolean operators ’AND’ and ’OR’ were used to combine the keywords and construct the search strategy.

Study selection

After removing duplicate articles using EndNote software version x9, two investigators independently screened the articles based on the title and abstract (JZL, HYL). Following that, another two investigators (WFL, MMS) performed a thorough assessment to identify studies that met the inclusion and exclusion criteria.

The inclusion criteria were: (1). Studies reporting dental students’ and dental practitioners’ acceptance, reluctance, or hesitancy to receive Covid-19 vaccination; (2). Cross-sectional study; (3). Studies were conducted during the COVID-19 pandemic; (4). No language restriction on published articles. Meanwhile, the exclusion criteria were: (1). Studies that combined data of all healthcare professionals; (2). Case-control, cohort study, expert opinions, reviews, commentaries, editorials, and short communications; (3). Mean and standard deviation on the acceptance or hesitancy level are not reported; (4). Studies conducted before the COVID-19 pandemic. Calibrations between investigators were carried out to assess interrater reliability. The average concordance was calculated with the Kappa value to compare the investigators’ decisions on inclusion and exclusion [22]. Any conflicts that arose throughout the search were addressed and resolved with the assistance of the fifth investigator (GSSL).

Data extraction

The following variables were extracted from each article using a standardised excel spreadsheet form to aid comparability: authors, year of publication, country, type of study, sample size, participant group, gender, age, evaluation tool, response rate and the overall outcomes. One investigator (GSSL) double-checked the accuracy of the data, and any disputes were handled by consensus among all authors.

Risk of bias assessment

Four investigators (HYL, JZL, WFL, MMS) evaluated the risk of bias for each included study using the Joanna Briggs Institute (JBI) critical appraisal checklist for analytical cross-sectional studies [23]. Either a ‘Yes’, ‘No’, ‘Unclear’ or ‘Not Applicable’ was assigned for each domain and the studies were categorised as ‘Include’, ‘Exclude’ or ‘Seek further info’. The Oxford Centre for Evidence-Based Medicine (OCEBM) guideline was employed to determine the level of evidence in each study [24]. The kappa coefficient was used to estimate inter-examiner agreement among all investigators throughout the risk of bias and level of evidence assessments. Besides, any disagreements were handled by discussion among all investigators until a consensus was reached.

Statistical analysis

All the included primary studies were chosen for quantitative analysis. The weighted mean acceptance rates of COVID-19 vaccination among dental students and dental practitioners from each included study were estimated using a single-arm meta-analysis based on the DerSimonian-Laird random-effects model. The analysis was carried out using the OpenMeta [Analyst] software (CEBM, Oxford, UK) with a significance level of 0.05 and 95% confidence intervals (CI). If the expected upper limit of the 95% confidence interval was larger than 1.0, the upper limit was set to 1.0. The Higgins’ I2 statistic was used to identify the degree of data heterogeneity with I2: < 30% = acceptable heterogeneity, I2: 30–60% = moderate heterogeneity, I2: > 60% = substantial heterogeneity [25]. Subgroup analysis and meta-regression were employed to determine the effect of different geographical regions, country income levels and sample sizes on the acceptance rates of COVID-19 vaccination. In addition, Egger’s test was employed to investigate publication bias.

Results

The initial electronic search generated a total of 231 studies. 89 papers were removed after duplication was eliminated, followed by 106 articles that were excluded based on titles and abstracts. The remaining 36 articles were chosen for full-text analysis. Finally, only 10 articles were included in the current review [12, 13, 16–20, 26–28]. The average inter-investigators Kappa score for preliminary article screening (titles and abstracts) and the second screening (full-text assessment) were 0.71 and 0.69, indicating a ’strong’ agreement [22]. Fig 1 depicts the reasons for article exclusion, whereas Table 1 summarises the characteristics of the included studies.

Fig 1

PRISMA flowchart.

Study selection and reasons for study exclusion according to the PRISMA guidelines.

Table 1

Characteristics of the included studies.

Author	Year	Country	Study design	Sample size	Participant groups	Gender	Age (Mean)	Evaluation tool	Response rate	Results
Nasr L et al. [16]	2021	Lebanon	cross-sectional	802	GDP, DSp	Males = 292 Females = 237	40.54 ± 14.01	self-administered questionnaire	529 (66%)	Already received or willing to receive COVID-19 vaccine (455/529)
Belingheri M et al. [20]	2021	Italy	cross-sectional	761	GDP	Male = 301Female = 120	N/A	self-administered survey	421 (55%)	(346/421) 82% declared intent to be vaccinated
Mascarenhas AK et al. [18]	2021	USA	cross-sectional	1481	DSt	Male = 42%Female = 58%	26.8 ± 3.8	self-administered survey	238 (16%)	(139/238) 56% willing to receive Vaccine once FDA approved
Zigron A et al. [13]	2021	Israel	cross-sectional	506	GDP, PDSt, DSp	Male = 43%Female = 57%	36.3	self-administered survey	N/A	overall rate of acceptance for a COVID-19 vaccine: 85%
Riad A et al. [26]	2021	22 countries	cross-sectional	6639	DSt	Male = 1836 Female = 4682 Non-binary = 53 Not disclosed = 68	22.06 ± 2.79	self-administered questionnaire	N/A	Acceptance levels among dental students were found to be 63.5%
Papagiannis D et al. [17]	2021	Greece	cross-sectional	340	GDP, MP, P	Male = 51.2%Female—48.8%(Include all HCW)	44.7 ± 10.97(Include all HCW)	self-administered questionnaire	Dentist only—80 (24%)	Dentists reported the highest percentage for Covid-19 vaccine acceptability (82.5%)
Kateeb E et al. [12]	2021	Palestine	cross-sectional	417	DSt	Male = 119Female = 295Prefer not to say = 3	N/A	self-administered questionnaire	N/A	57.8% (n = 241) of the participants are willing to be vaccinated
Al-Sanafi M et al. [19]	2021	Kuwait	cross-sectional	1019	GDP, MP, P, Nrs, LT	Male = 101Female = 69(Only GDP)	31 ± 7.1(Only GDP)	questionnaire	N/A	91.2% (155/170) of dentists get or intend to get COVID-19 vaccine
Aslam S et al. [27]	2021	Pakistan	cross-sectional	370	GDP	Male = 94Female = 206	N/A	self-administered questionnaire	300 (81%)	50% (150/300) of the dentists are willing to receive the vaccine
Paramashivaih R et al. [28]	2021	India	cross-sectional	250	GDP, DSp, PDSt	Male = 56 Female = 68	N/A	self-administered questionnaire	124 (49.6%)	(118/124) of the participants received COVID-19 vaccination

*GDP: General dental practitioners’ DSp: Dental specialists; DSt: Dental students; PDSt: Postgraduate dental students; MP: Medical physicians; P: Pharmacists; Nrs: Nurses; LT: Lab technicians; HCW: Healthcare workers; N/A: Not available.

All included studies were published in 2021 and employed a cross-sectional design. Four studies were originated from Middle Eastern countries [12, 13, 16, 19], two studies from European countries [17, 20], one study from North America [18], two studies from South Asian countries [27, 28], and one study included participants from 22 different countries [26]. Among them, seven studies explored the acceptance of dental practitioners towards COVID-19 vaccination [13, 16, 17, 19, 20, 27, 28], while the remaining three studies focused on dental students’ acceptance or hesitancy [12, 18, 26]. Overall, the response rate ranged from 18% to 81%.

Table 2 shows the risk of bias assessment using the JBI critical appraisal tool and the level of evidence for each included study. Generally, four studies were considered moderate risk [12, 16, 17, 28], while the remaining were stated as low risk of bias. All included studies were rated ‘Yes’ for domains 1, 2, 3, 4, and 5. Three studies were given ‘No’ for domain 7 [16, 17, 28], whereas four studies were given ‘No’ for domain 6 [12, 16, 17, 28]. Only one study was deemed ‘No’ for domain 8 [27]. Furthermore, all studies were rated Level 3 based on the level of evidence due to a lack of blinding among the investigators or assessors. The k coefficients for the risk of bias and level of evidence assessments were 0.68 and 0.75, respectively, indicating a ’strong’ agreement.

Table 2

Risk of bias assessment using the Joanna Briggs Institute (JBI) critical appraisal tool for analytical cross-sectional studies and the level of evidence of each included study.

Studies	Domains								Overall Appraisal	Level of Evidence
	1	2	3	4	5	6	7	8
Nasr L et al. [16]	Y	Y	Y	Y	Y	N	N	Y	Include	3
Belingheri M et al. [20]	Y	Y	Y	Y	Y	Y	Y	Y	Include	3
Mascarenhas AK et al. [18]	Y	Y	Y	Y	Y	Y	Y	Y	Include	3
Zigron A et al. [13]	Y	Y	Y	Y	Y	Y	Y	Y	Include	3
Riad A et al. [26]	Y	Y	Y	Y	Y	Y	Y	Y	Include	3
Papagiannis D et al. [17]	Y	Y	Y	Y	Y	N	N	Y	Include	3
Kateeb E et al. [12]	Y	Y	Y	Y	Y	N	Y	Y	Include	3
Al-Sanafi M et al. [19]	Y	Y	Y	Y	Y	Y	Y	Y	Include	3
Aslam S et al. [27]	Y	Y	Y	Y	Y	Y	Y	N	Include	3
Paramashivaih R et al. [28]	Y	Y	Y	Y	Y	N	N	Y	Include	3

Domain 1: Were the criteria for inclusion in the sample clearly defined?

Domain 2: Were the study subjects and the setting described in detail?

Domain 3: Was the exposure measured in a valid and reliable way?

Domain 4: Were objective, standard criteria used for measurement of the condition?

Domain 5: Were confounding factors identified?

Domain 6: Were strategies to deal with confounding factors stated?

Domain 7: Were the outcomes measured in a valid and reliable way?

Domain 8: Was appropriate statistical analysis used?.

The acceptances of COVID-19 vaccination among dental students and dental practitioners is presented in Table 3. Meta-analysis was performed when three or more studies are available. Based on the single-arm meta-analysis (Fig 2), the weighted mean acceptance rates of COVID-19 vaccine among dental students and dental practitioners were 60.5% [CI: (56.1, 65.0)] and 81.1% [CI: (72.4, 89.8)], respectively. The I2 of the weighted mean acceptance rates of COVID-19 vaccine among dental students and dental practitioners were 73.65% and 96.86%, respectively, indicating the existence of substantial heterogeneity among the included studies for quantitative analysis.

Table 3

Dental students and dental practitioners’ acceptance towards COVID-19 vaccination.

Studies	Year	Acceptance towards COVID-19 Vaccination
		Dental Students	Dental Practitioners
Nasr L et al. [16]	2021	n/a	(455/529)
Belingheri M et al. [20]	2021	n/a	(346/461)
Mascarenhas AK et al. [18]	2021	(139/238)	n/a
Zigron A et al. [13]	2021	n/a	(405/506)
Riad A et al. [26]	2021	(4220/6639)	n/a
Papagiannis D et al. [17]	2021	n/a	(66/80)
Kateeb E et al. [12]	2021	(241/417)	n/a
Al-Sanafi M et al. [19]	2021	n/a	(155/170)
Aslam S et al. [27]	2021	n/a	(150/300)
Paramashivaih R et al. [28]	2021	n/a	(118/124)

*n/a: Not Available.

Nasr L et al. pooled data for general dentists and dental specialists.

Zigron A et al. pooled data for general dentists and dental specialists.

Riad A et al. students that answered, ‘totally agree’ and ‘agree’ will be deemed as acceptance towards COVID-19 vaccination.

Kateeb E et al. pooled data for dental students and dental fresh graduates.

Paramashivaih R et al. pooled data for general dentists, dental specialists and postgraduate dental students.

Fig 2

Meta-analysis of COVID-19 vaccine acceptance.

Single-arm meta-analyses showing the weighted mean acceptance rates of COVID-19 vaccination among dental students and dental practitioners.

Sensitivity Analyses were conducted for both dental students and dental practitioners. The highest and lowest weighted mean acceptance rates of COVID-19 vaccine among dental students were 61.9% [CI: (57.2, 66.6)] and 58.0% [CI: (54.2, 61.8)] when Kateeb E et al. [12] and Riad A et al. [26] were excluded, respectively. Meanwhile, the highest and lowest weighted mean acceptance rate of COVID-19 vaccine among dental practitioners were 86.3% [CI: (81.5, 91.1)] and 78.8% [CI: (69.5, 88.0)] when Aslam S et al. [27] and Paramashivaih R et al. [28] were omitted, respectively.

Considering the sheer degree of data heterogeneity, subgroup analyses were performed to determine the impact of different geographical regions and country income levels on COVID-19 vaccine acceptance rates (S1 Table). Data were classified into four geographical regions: Middle East, Europe, North America, and South Asia (depending on where each included study was conducted), and they were divided into three categories: high, upper-middle, and lower-middle based on their respective country income levels. Since study done by Riad A et al. [26] was eliminated due to the extensive pooling of respondents from multiple countries, subgroup analysis on dental students’ acceptance level was not undertaken as only two remaining studies were left [12, 18]. On the other hand, dental practitioners in the Middle East had a considerably higher weighted mean acceptance rate of COVID-19 vaccination (p < 0.001) than those in Europe and South Asia. Meanwhile, dental practitioners from high-income countries demonstrated significantly higher acceptability of the COVID-19 vaccine (p < 0.001) than those from upper-middle and lower-middle-income countries. Nonetheless, subgroup analyses on the effect of gender and participants’ age on the acceptance level were not possible in the current review since the data were aggregated in the primary studies. It is also not feasible to divide dental practitioners into subgroups such as general dentists, dental specialists, or postgraduate dental students due to a paucity of data.

Meta-regression was performed to evaluate the effect of the response sample sizes of each study on the acceptance rate of the COVID-19 vaccine (S2 Table). No significant differences were found for both dental students (p = 0.06) and dental practitioners (p = 0.611), signifying that the sample size of each study does not have any direct effect on the degree of data heterogeneity. Egger’s test revealed that there was no evidence of significant publication bias in the acceptance rates of COVID-19 vaccine among dental students and dental practitioners. (Egger’s test: p-value = 0.11, and 0.08, respectively).

Discussion

The present systematic review aimed to comprehensively investigate the acceptance of COVID-19 vaccination among dental students and dental practitioners in order to provide valuable insights for future COVID-19 vaccination implementation. Based on the current single-arm meta-analysis, dental practitioners showed a high acceptance rate towards COVID-19 vaccination (81.1%) which is higher than the values reported in previous systematic reviews conducted on healthcare workers that ranged from 51% to 73% [8, 29]. The authors speculated that the disparities in acceptance rates could be explained by the passage of time [19], as previous reviews included studies or surveys conducted at a period when comprehensive scientific evidence on COVID-19 was not yet available and healthcare professionals’ acceptance of the vaccine at that moment was still confined. Conversely, the primary studies included in the present review were recently published in the year 2021. Such differences can also be explained by the increased awareness of the high infectivity of COVID-19 disease and its ability to induce more severe illnesses and complications [30]. Also, COVID-19 vaccine mandates among healthcare workers implemented by various countries in recent months may have increased the acceptance rate of COVID-19 vaccine among healthcare workers.

Acknowledging dental practitioners’ perceptions on COVID-19 vaccination is critical as they play a key role in educating patients and tackling vaccine reluctance among the general public [19]. Undeniably, dental practitioners were exposed to a high risk of cross-infection in clinical practice, and preventive measures such as proper use of personal protective equipment when performing aerosol-generating procedures have raised awareness of the importance of mitigating the spread of infection, resulting in increased vaccination acceptance [16, 20]. Despite the significant likelihood of being infected by the viruses, the prevalence of COVID-19 infection among dental practitioners was reported to be low with a prevalence rate of 2.6% in the United States and 1.9% in France, respectively [31, 32]. The authors speculated that this could be attributed to the improved preventive measures, as well as the increased vaccine acceptability and uptake.

Moreover, most countries also mandated vaccination policies for healthcare professionals which may have an impact on dental practitioners’ acceptability towards COVID-19 vaccination [33]. Other factors such as the knowledge and concern of being infected with the SARS-CoV-2 may render dental practitioners to accept vaccination [16, 27]. In fact, several studies have proven that prior influenza vaccination history has a significant influence on the acceptability of covid-19 vaccination [34, 35], and this could be the driving force for the high degree of acceptance among dental practitioners. Nonetheless, it should be highlighted that vaccination acceptance may have been overestimated as dental practitioners who were not interested in receiving the vaccine may be unlikely to participate in the survey or questionnaire [16].

Subgroup analysis suggested that both geographical regions and country income levels significantly affect the acceptance of vaccination among dental practitioners. It was discovered that dental practitioners in the Middle East had a considerably higher acceptance rate of COVID-19 vaccination compared to other regions. This could be attributed to the surge of COVID-19 cases and the increase in mortality rate (especially among dentists and physicians) in the Middle East region at the time of the surveys [16, 19]. The authors postulated that dental practitioners’ perspectives about the coronavirus have shifted from reluctance to acceptance as a result of their fear of infection [20]. On the other hand, a low acceptance rate of the COVID-19 vaccination in South Asia, particularly in Pakistan, was primarily owing to public figures’ conspiracy theories, lack of confidence in locally manufactured vaccines and lack of effort by public health authorities to educate dental healthcare workers [27]. Thus, tackling the underlying cultural and political factors that cause vaccine hesitancy is crucial to boost vaccination uptake. The present review also showed that the country’s income level was a significant determinant of the acceptance rate of COVID-19 vaccination among dental practitioners. This is consistent with a previous systematic review reporting that the highest acceptance rate of COVID-19 vaccine among healthcare workers was from high-income countries, while the lowest acceptance rate was seen from low-income countries [14]. Furthermore, despite growing evidence of the safety and effectiveness of presently used vaccines, one explanation for the disparity in COVID-19 vaccine uptake across countries might be attributed to the vaccine’s availability [36]. Since vaccine development takes time, administrating approved vaccines to a wide population would be challenging. Nonetheless, it can be predicted that vaccination uptake will continue to rise as vaccine availability increases [37].

In contrast to dental practitioners, dental students in the present analysis had a lower weighted mean acceptance rate (60.5%) towards COVID-19 vaccination. Their willingness and readiness to accept the vaccine were found to be greatly reduced due to a lack of trust in the government and vaccination data from the pharmaceutical sectors [12, 26]. Most students also did not consider themselves at risk of being infected by the coronavirus, as the available evidence reported that the COVID-19 infection rate among dentists in the United States dentist was as low as 0.9% [18, 38]. Other contributing factors to the poor acceptance rate among dental students included socioeconomic status, perceived COVID-19 vaccination knowledge, and gender [16, 18]. Nonetheless, subgroup analysis was not performed among dental students due to a paucity of published articles. It is still worth noting that understanding the underlying causes of vaccination apprehension, especially among dental students, can pave the way for higher education institutions to reinforce immunization knowledge and understanding.

The current review used the JBI critical appraisal checklist for cross-sectional studies to critically evaluate the risk of bias in each included study. The JBI risk of bias assessment tool is among the most widely used tools for assessing the internal validity of the included studies due to its ease of comprehension and implementation [39]. Four studies were rated ‘No’ for domain 6 (Were strategies to deal with confounding factors stated?) [12, 16, 17, 28]. Confounding factors such as the respondents’ gender and age should be addressed to prevent the true effects of the study from being concealed. As there may be disparities in the confounding factors taken into consideration, determining what the researchers performed to adjust the confounders could be challenging. Restriction and stratification are two approaches to deal with confounders. Researchers may, for instance, limit their study to a specific age group of respondents or divide the population into strata or subgroups for comparison [40]. Overlooked confounders might increase the odds for findings to be skewed and their validity to be questioned. Thus, confounding factors must be carefully identified and dealt with to optimize reliability.

In addition, three studies failed to measure the outcomes in a valid and reliable way as they did not mention whether the questionnaires or surveys used were pre-validated [16, 17, 28]. For a questionnaire or survey to be considered acceptable, it must have two key characteristics: reliability and validity. It is advisable that qualified experts should be involved in the face validation process to evaluate each questionnaire item, followed by a pilot test on a small sample of respondents. Moreover, the authors recommended that content and construct validity should be explored when validating a questionnaire [41]. Only one study failed to specify appropriate statistical analysis used [27]. The choice of an appropriate statistical approach is critical, as it will influence the overall outcome. The present review also reported no evidence of significant publication bias among the articles included, which could be owing to the extensive literature search that included grey literature.

It can be concluded that dental practitioners, particularly those from the Middle East regions and high-income countries, demonstrated high acceptability of COVID-19 vaccination. While dental students showed a lower acceptance towards COVID-19 vaccination, future research should concentrate on the reported unfavourable attitudes and hesitation factors. Furthermore, scientific research on the impact of geographical regions and country economic levels on vaccination acceptability levels among dental students should be explored. It is imperative to eradicate vaccination hesitancy among dental students and dental practitioners, given their critical role in educating the public on the awareness and importance of vaccination. Establishing immunisation campaign strategies and implementing courses or modules on vaccination literacy in the dental curriculum should be prioritised in the fight against the pandemic. Meanwhile, it is also essential to keep records of how dental students and dental practitioners respond to vaccinations and adjust vaccination strategies as required.

Strengths and limitations

The strengths of the current systematic review include the registration of the study protocol in the PROSPERO database for better transparency and preclude incidental review duplication [42], a comprehensive literature search was performed in eight electronic databases to ensure that no relevant articles were missed, the literature search and data extraction were carried out by several independent investigators, and a well-designed risk of bias assessment tool was used to appraise the included articles [43]. Moreover, another merit of the present review is that there are no language constraints on the included articles. Merely including specific language papers will limit the breadth of the studies included and introduce significant language bias into the current review [44]. To account for between-study variability, a random-effects model based on the DerSimonian-Laird was adopted in the current analysis as the authors considered that the true effect size varied among studies since each study is different. Furthermore, a random-effects model can also help to account for the significant heterogeneity identified in the present review [45]. Several drawbacks were identified in the current study. First, the limited amount of studies included in the present meta-analysis may hinder the investigators from obtaining reliable inferential outcomes [46]. However, it is understandable that such a prerequisite of including a large number of studies is rarely achieved, notably in the field of dentistry [47]. Another flaw in the current systematic review is the degree of precision in data synthesis, as the analysis was not feasible for respondents’ age, gender, or past vaccination history, all of which could influence the overall results. Although subgroup analyses were conducted to assess the effect of geographical regions and country income levels on dental practitioners’ COVID-19 vaccine acceptance rates, no analysis concerning dental students was carried out as the research included were limited. Also, different studies utilised different questionnaires or surveys, which could have resulted in response bias due to the lack of general standardisation. Another shortcoming is that the majority of the studies are from the Middle East, Europe, and South Asia. Therefore, drawing solid conclusions on the global acceptance of the COVID-19 vaccine is impractical, and more well-designed cross-sectional studies focusing on the perceptions of oral health professionals from other regions are warranted.

Subgroup analyses of geographical regions and country income levels on the acceptance rates (%) of COVID-19 vaccine among dental practitioners.

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Meta-regression evaluating the effect of sample size of each study on the acceptance rates (%) of COVID-19 vaccine among dental students and dental practitioners.

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PRISMA 2020 for abstracts checklist.

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PRISMA checklist.

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8 Feb 2022

16 Feb 2022

Reviewer 1

1. Add more information in the background section, such as the purpose of study, etc.

Reply:

The background has been amended.

Page 2, Line 3-6:

‘The contemporary COVID-19 pandemic has prompted researchers across the world …… acceptance towards COVID-19 vaccination is still scarce.’

2. Introduction: Minor information on the variants of COVID-19 and their future challenges can be included i.e., Doi: 10.1007/s15010-021-01734-2.

Reply:

Several points have been added to the introduction.

Page 4:

“Several strains of SARS-CoV-2 have been discovered throughout the pandemic and are categorized into three groups …… to curb the widespread of the viruses”

3. The English may be improved (Minor).

Reply: The manuscript has been proofread by an English native speaker.

4. The graphical figure resolution is low. It has to be improved for publication. It isn't easy to interpret results from them.

Reply: The authors would like to thank the reviewer for raising this concern. High-resolution figures (Figure 1 and Figure 2) will be provided to the journal editor.

5. Proper figure legends are also missing from the manuscript.

Reply: Figure legends were written in the text.

Page 9:

“Fig 1. PRISMA flowchart. Study selection …… PRISMA guidelines”

Page 13

“Fig 2. Meta-analysis of COVID-19 vaccine acceptance …… and dental practitioners.”

6. The authors should cross-check all abbreviations in the manuscript. Provide all abbreviations in a separate paragraph.

Reply:

All abbreviations have been cross-checked and a separated section ‘Abbreviation’ was added into the manuscript.

7. Add the limitation of the manuscript in a separate section.

Reply:

A separated section of limitation has been added.

Reviewer 2

1. Introduction, please include some quantitative information about COVID-19 variants and their challenges in its prevention.

Reply:

Several points have been added to the introduction.

Page 4:

“Several strains of SARS-CoV-2 have been discovered throughout the pandemic and are categorized into three groups …… to curb the widespread of the viruses”

2. Discussion, please highlight minor information about cases, mortality, and casualty of COVID-19 in case of dental students and dental practitioners.

Reply:

The authors added few points in the discussion.

Page 16:

“Despite the significant likelihood of being infected by the viruses, …… the increased vaccine acceptability and uptake.”

3. Please include 2 or 3 figures at least to represent your results in the revised manuscript.

Reply:

Two figures were included in the manuscript:

Figure 1 – PRISMA flowchart showing the study selection

Figure 2 – Single-arm meta-analysis showing the outcome of the present review

Submitted filename: Response to Reviewers.docx

Click here for additional data file.

10 Mar 2022

11 Mar 2022

1. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Reply: The reference list was amended accordingly.

Reviewer 3

1. Abstract:

With 334 words, this section is much too long. Please stick to the Journal guidelines and reduce to the word maximum which is 300.

- With your revision, give priority to the results.

- With your Conclusions, please stick exclusively to your revised aims. Do not simply repeat your results here. Instead, provide a reasonable and generalizable extension of your outcome.

Reply: Dear reviewer, the authors attempted to reduce the number of words, and we agreed to use the full name, such as Joanna Briggs Institute, rather than JBI. Hence, the word count may slightly exceed.

The authors did not repeat the results, but we provide a generalized outcome:

“Despite the high degree of acceptance of COVID-19 vaccination among dental practitioners, dental students still demonstrated a poor acceptance”

An extension of the outcome was also provided:

“These findings highlighted that evidence-based planning with effective approaches is warranted to enhance the knowledge and eradicate vaccination hesitancy, particularly among dental students”

2. Intro

- Would seem sound.

- Please add some thoughts on your rationale. Dentists/dental students are considered a part of the society. Consequently, why should they differ from the society? Please clarify your idea when starting this project.

Reply: The authors have addressed the reason for conducting such a study because dental practitioners and dental students are classified as high-risk group.

“Dental practitioners are among the healthcare workers classified as high-risk of infection during the COVID-19 pandemic due to the nature of their profession and the close proximity of the dental team to the patients”

Therefore, they should be distinguished from the general public or society in order to determine the real impact of COVID-19 vaccination acceptance among them.

3. Results

- "Finally, only 10 articles are included (...)" must read "Finally, only 10 articles were included (...)".

- Level of evidence of included studies would seem poor. Please comment in this aspect. Why did you include such poor papers? And why have those poor papers been published? Please discuss thoroughly.

- Again, please stick to Journal guidelines. "(P=0.006)" must read "(p = 0.006)". "p" must be italicized.

- "No significant differences were found for both dental students (P=0.006) (...)." "(p = 0.006)" would indicate a significant difference, don't you think so?

Reply: The word ‘are’ had been changed to ‘were’.

The authors would like to thank the reviewer for raising this concern. Due to the nature of the study design, the level of evidence of the included cross-sectional studies appeared to be poor, as none of the research involved blinding the investigators or assessors.

Nonetheless, the included cross-sectional studies are still valuable as they can aid in determining the degree of acceptance of COVID-19 vaccination during this specific period.

The author also added the phrase:

“…due to a lack of blinding among the investigators or assessors”

Please accept the authors' sincere apologies for the 'p = 0.06' error.

5. - "To the best of the authors’ knowledge, it is also the first of its kind to critically summarise, analyse, and provide reliable evidence-based findings from existing research on the acceptability of COVID-19 vaccination in the dental community." Don't be too proud of your work, and do not re-repeat your pride. Compare to your Intro section ("To the best of the authors’ knowledge, no systematic review has been reported (...)"), and revise carefully. All readers will acknowledge your work, even if you will not show "the best of your knowledge"...

Reply: The authors have deleted the sentence in the first paragraph of the discussion section.

6. "(...) dental practitioners showed a high acceptance rate towards COVID-19 vaccination (81.1%) which is higher than the values reported in previous systematic reviews conducted on healthcare workers that ranged from 51% to 73% [8, 29]." I do not agree that this would be a "high acceptance rate". First, dental practitioners are a part of the medical science community, and this would call for a considerably higher rate. Second, there are countries with much higher rates, even with the normal population (see, for example, Arabic Emirates, Chile, or Portugal). Consequently, there is no need to be satisfied. Please discuss.

Reply: The authors would like to express their gratitude to the reviewer for sharing their thoughts on this matter. However, the authors believe that different religions and beliefs about COVID-19 immunization do exist, as detailed in the introduction section. It is also unfair to assume that all dental practitioners across the world, although being part of the medical community, would have a high acceptance rate.

The authors were not particularly proud with the 81.8% acceptance rate; rather, we were comparing the acceptance rate to data reported among healthcare personnel in order to provide a more comprehensive picture to the readers.

7. "(...) a comprehensive literature search was performed in eight electronic databases to ensure that no relevant articles were missed." Please note that there are more databases. What about other languages? Please provide a sound assessment of the probability on how many papers have been missed, and how this could influence your outcome.

Reply: The authors did not impose any language restriction and the limitations were addressed in the manuscript.

8. Therefore, drawing solid conclusions on the global acceptance of the COVID-19 vaccine is impractical (...)." First, this would mean that publishing your paper will not be advocated. Second, why did you include a Conclusion section ("it can be concluded that dental practitioners, (...).") here?

Reply: The authors intended to provide recommendations for future research, advocating that more comparable studies be undertaken in order to reach a solid conclusion.

Of course, this does not imply that the existing manuscript has no value or merit. The authors believe that publishing the current data, it would raise awareness among dental researchers throughout the globe to delve deeper into this context.

Furthermore, conducting a systematic review allows readers to recognize the existing limitations.

The conclusion section was eliminated, and the points were relocated to the last paragraph of the discussion section.

9 Again, see comments given above, and revise carefully.

- Phrases given with "Furthermore, scientific research on the impact of (...)" to "(...) it is also essential to keep records of how dental students and dental practitioners respond to vaccinations and adjust vaccination strategies as required." would seem right, but are not considered Conclusions and must be copied & pasted to the Disc section.

Reply: The conclusion section was eliminated, and the points were relocated to the last paragraph of the discussion section.

Submitted filename: Response to Reviewers.docx

Click here for additional data file.

1 Apr 2022

5 Apr 2022

1. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice

Reply:

The reference list was amended accordingly.

The second reference (No.2) has been changed.

Reviewer 1

1. In the study selection section, the authors mention one of the exclusion criteria as " poor data reported on acceptance or hesitancy level." Please report how authors have differentiated between poor data and sound data. Also, what parameters are considered to determine this selection?

Reply:

The authors have amended the following sentence for better understanding:

“Mean and standard deviation on the acceptance or hesitancy level are not reported”

2. The English of the manuscript may be improved. There are instances in the manuscript where the construction of sentences may be better (Minor).

Reply:

The manuscript has been proofread by a native English speaker.

3. The studies considered for the study are from different countries. The number of COVID-19 cases (danger) and the availability of the vaccine to citizens are different in each country. Please discuss these factors in the discussion.

Reply:

The authors appreciate the suggestion raised by the reviewer and have included some points in the discussion:

“Furthermore, despite growing evidence of the safety and effectiveness of presently used vaccines …… continue to rise as vaccine availability increases [37].”

Reviewer 3

1. Maximum word count is 300. Again, please shorten, and note that this is due to the various databases and must be revised.

Reply:

The authors have revised the abstract to 300 words.

Submitted filename: Response to Reviewers.docx

Click here for additional data file.

7 Apr 2022

COVID-19 Vaccination Acceptance Among Dental Students and Dental Practitioners: A Systematic Review and Meta-Analysis

PONE-D-22-00027R3

Dear Dr. Lin,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Congratulations, and best wishes!

Prof. Dr. med. dent. Dr. h. c. Andrej M Kielbassa

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Prof. Dr. med. dent. Dr. h. c. Andrej M Kielbassa

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #3: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The author has addressed all my comments. Therefore, there is no basis on which manuscript can be rejected for publication.

I congratulate the authors for the work.

Reviewer #3: With the help of the reviewers, this revised and re-submitted paper has been considerably improved, and is ready to proceed.

**********

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Reviewer #1: Yes: Aditya Kumar Sharma

Reviewer #3: No

11 Apr 2022

PONE-D-22-00027R3

COVID-19 Vaccination Acceptance Among Dental Students and Dental Practitioners: A Systematic Review and Meta-Analysis

Dear Dr. Lin:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Prof. Dr. med. dent. Dr. h. c. Andrej M Kielbassa

Academic Editor

PLOS ONE