Effectiveness of educational interventions on vaccine hesitancy: a systematic review and meta-analysis

¹Africa Centre of Excellence in Public Health and Toxicological Research, University of Port Harcourt, Port Harcourt, Nigeria

^&Corresponding author
Oluwaseun Omotola Omoyele, Africa Centre of Excellence in Public Health and Toxicological Research, University of Port Harcourt, Port Harcourt, Nigeria

Introduction    

Vaccination is a vital public health intervention that has been shown to be crucial in the fight against epidemics and pandemics, as highlighted by the recent COVID-19 pandemic [1]. Vaccines can effectively prevent more than 20 deadly diseases and help avert two to three million deaths globally each year [2]. Vaccination programs are a major contributor to improved health outcomes, effectively stopping the spread of deadly epidemics of diseases such as influenza, tetanus, measles, diphtheria, and pertussis [3]. Immunizations have often been essential in eradicating deadly diseases like poliomyelitis and smallpox, while the prevalence of diseases like rubella, mumps, and diphtheria has decreased dramatically by 95% [4].

Vaccines have a significant impact on individual health as well as the security of the world's health, particularly in the fight against antibiotic resistance [5]. In addition to reducing the need for drugs, vaccination prophylaxis significantly reduces the prevalence of infectious diseases. Since vaccines prevent illnesses, they instantly address the problem of antibiotic resistance by lowering the requirement for antibiotic treatments [6]. It is increasingly recognised that reducing the development and spread of antibiotic resistance is one of the intended results of public health initiatives [4]. Vaccination is one of the best investments in health that can be made, according to the World Health Organisation [5].

Despite significant progress in healthcare, approximately 20 million infants annually lack access to proper immunizations [3]. Furthermore, global vaccination rates have recently stagnated, with some regions experiencing declines [7]. The European Centre for Disease Prevention and Control (ECDC) highlights vaccine hesitancy as a major obstacle, despite the proven safety and efficacy of vaccines. The World Health Organization identifies vaccine acceptance and reluctance as one of the top 10 global health threats, alongside critical issues like HIV and climate change [8].

Vaccination aversion varies based on the vaccine and target group, encompassing attitudes toward mandates, general trust in vaccination, and beliefs about vaccine safety [8]. Educational interventions have been identified as a key strategy for improving vaccine confidence and increasing vaccine uptake through improved knowledge, risk perception, and informed decision-making [9].

Healthcare professionals (HCPs) are uniquely positioned to significantly contribute to this educational effort. Viewed as reliable sources of information, HCPs exert considerable influence on vaccination decisions [10]. The provider-patient relationship is a vital component of vaccination confidence, as their recommendations can significantly impact decision-making [11]. With appropriate training and skills, HCPs can effectively communicate with individuals who are hesitant or resistant to immunizations [8]. Targeted educational interventions can enhance HCPs' knowledge and understanding of the risks associated with vaccine-preventable diseases, including transmission, morbidity, and mortality [8]. By reducing misunderstandings and promoting informed decision-making, this engagement has the potential to increase vaccine acceptance and improve public health outcomes [12].

Vaccination hesitancy poses a significant public health risk due to the complex interplay of individual beliefs, social influences, contextual factors, and vaccine-specific concerns. Despite extensive research on these factors, there is limited understanding of the effectiveness of educational interventions in addressing them, particularly regarding their long-term impact. To address this gap, this comprehensive review synthesizes evidence from various educational interventions, including interactive videos, immersive virtual reality experiences, engaging seminars, community-based initiatives, targeted campaigns, and social media partnerships (using Facebook, Instagram, and YouTube). Given these knowledge gaps, a systematic synthesis of the available evidence is required to determine which educational interventions are most effective, whether effectiveness differs across vaccine types, and what factors contribute to variability in intervention outcomes.

Research: this study seeks to answer the following questions: 1) What is the comparative effectiveness of different educational interventions in improving vaccination uptake, and do multi-component interventions provide additional benefits compared with the most effective single-component intervention? 2) How does the effectiveness of educational interventions vary across vaccine types, particularly for Tdap, HPV, influenza, and measles, mumps, and rubella (MMR) vaccines? 3) What factors contribute to the observed heterogeneity in intervention effectiveness, and to what extent do study design characteristics explain differences in outcomes across studies?

Hypothesis: multi-component educational interventions are more effective than single-component educational interventions in improving vaccine uptake and reducing vaccine hesitancy across different populations and vaccine types.

Overall objective: to evaluate the effectiveness of educational interventions in reducing vaccine hesitancy and improving vaccine uptake through a systematic review and meta-analysis.

Specific objectives: to compare the effectiveness of different educational interventions in improving vaccination uptake; to evaluate whether multi-component educational interventions are more effective than single-component interventions; to examine differences in intervention effectiveness across vaccine types; to assess the effects of educational interventions on vaccine-related knowledge, attitudes, intentions, and uptake; to investigate sources of heterogeneity among included studies.

Methods     

Study design: this systematic review adhered to the PRISMA guidelines, and a PRISMA flow diagram (Figure 1) illustrated the inclusion of the 66 publications. The characteristics and findings of the included studies were summarized in a table of evidence. This study employs a mixed-methods approach, synthesizing both qualitative and quantitative data. In addition, the protocol of this study was registered with PROSPERO and can be accessed via the internet.

Information sources: we systematically searched databases, which are PubMed, MEDLINE, Scopus, PsycINFO, Google Scholar, reference lists, and Grey literature.

Search strategy: the electronic search strategy was developed using the PICO framework and incorporated free-text keywords and Medical Subject Headings (MeSH). Boolean operators (AND, OR) and truncation (*) were applied where appropriate and adapted to the indexing requirements of each database. The search covered population, intervention, comparison, and outcome terms related to vaccine hesitancy, educational interventions, and vaccine uptake, with no geographical restrictions. The detailed search strategy, including keywords, MeSH terms, and Boolean logic, is presented in Table 1, and a systematic literature search was conducted on 14^th September 2024 using the search strategy: ("Vaccination" OR "Immunization") AND ("Vaccine Hesitancy" OR "Vaccination Refusal") AND ("Health Education" OR education OR communication OR training) AND (uptake OR acceptance OR confidence OR behaviour). The search yielded 1,006 records for screening and subsequent assessment for eligibility.

Eligibility criteria: concerning the geographical coverage, no geographical restrictions were applied. Studies from all countries and regions were eligible provided they met the inclusion criteria. Eligibility assessment was conducted independently by two reviewers using predefined eligibility criteria based on the PICO framework. The review includes studies focusing on educational interventions designed to increase vaccine uptake or reduce hesitancy among adults aged 18 and older or caregivers of children, encompassing diverse demographic backgrounds and health literacy levels. In addition, studies with the general population, children and adolescents, adults, parents and caregivers, healthcare workers, or vaccine-hesitant individuals or groups were considered.

Inclusion criteria: studies published from 1/1/2012 to 31/8/2024 in English, and in relation to PICO: 1) general population, children and adolescents, adults, parents and caregivers, healthcare workers, or vaccine-hesitant individuals or groups; 2) in terms of interventions, all health educational platforms-educational interventions, communication interventions, mobile-based health education, web-based educational programs, community outreach and engagement strategies; 3) based on comparison, anything such as standard care/no intervention, other types of interventions such as reminder systems, incentives or baseline or control group data besides educational interventions; 4) outcome-effects of educational interventions on vaccination rates, and also vaccine acceptance, vaccine hesitancy, vaccine confidence, vaccine uptake/coverage, change in attitudes or intentions toward vaccination or knowledge and awareness of vaccines.

Exclusion criteria: studies not evaluating educational interventions, non-peer-reviewed articles, commentaries, and editorials, and non-English.

Language: only research studies published in English were considered.

Study selection: comprehensive searches were conducted in PubMed, PubMed Central, MEDLINE, and SCOPUS to identify English-language studies published between 2012 and 2024. Two independent reviewers removed duplicates and screened titles, abstracts, and full texts against the predefined eligibility criteria. Reference lists of included studies were manually searched to identify additional eligible studies. Disagreements were resolved through discussion with a third reviewer, who also supervised data extraction to ensure consistency and minimize bias. The study selection process was managed using Microsoft Excel, and the detailed search strategy is presented in Table 1. The 2012-2024 period was selected to capture contemporary evidence, including methodological advances and changes in vaccine attitudes following the COVID-19 pandemic.

Study characteristics (included study designs): a total of 66 studies met the eligibility criteria and were included in the systematic review. These comprised randomized controlled trials (RCTs) (n = 20), cross-sectional studies (n = 15), observational studies (n = 8), quasi-experimental studies (n = 5), and other study designs (n = 18). The included studies involved the general population, children and adolescents, adults, parents and caregivers, healthcare workers, and vaccine-hesitant individuals or groups, and evaluated various educational interventions across different vaccine types and related factors. Of the 66 included studies, 22 (13 RCTs and 9 observational studies) provided sufficient quantitative data for inclusion in the meta-analysis, while the remaining studies were synthesized qualitatively.

Data collection and extraction: data were systematically extracted, organized, and analyzed from studies addressing the effectiveness of educational interventions in reducing vaccine hesitancy, guided by specific review questions. A comprehensive data abstraction sheet was developed to ensure consistency and thoroughness in data extraction. The sheet included categories, which aligned with the research questions, and these were the educational intervention (types of intervention such as videos, social media, seminars), comparison group, outcomes measured (example, vaccine uptake, hesitancy scores, knowledge, behaviour, and intention), results or key findings (such as statistical significance, effect sizes, p-values, confidence intervals), vaccine types studied, and intervention component analysis (single vs. multi-component intervention). A pilot test of the data abstraction sheet was conducted on a small sample of studies (5 studies) to identify any ambiguities or missing categories. The sheet was adjusted based on feedback to enhance clarity and usability.

Outcomes: the search strategy for this systematic review is based on the PICO framework, which facilitates the systematic identification of studies assessing the impact of educational interventions on adult vaccine hesitancy and uptake. The interventions of interest include various educational approaches that support information sharing between providers and recipients. These encompass interactive videos, virtual reality experiences, seminar presentations, school programs, community-based initiatives, targeted campaigns, in-person conversations, social media influencer partnerships, and multi-channel communication strategies via platforms like Facebook, WhatsApp, and YouTube. The comparison group consists of standard teaching methods that do not utilize these innovative techniques.

The primary focus is on the impact of these interventions on vaccination rates, but the review also examines vaccine knowledge, beliefs, acceptance, hesitancy, and intention. To provide a thorough evaluation of the available evidence, both randomized controlled trials (RCTs) and non-randomized study designs, such as observational and quasi-experimental studies, are included. This PICO framework guides the search strategy, ensuring the systematic review identifies relevant studies assessing the impact of educational interventions on vaccine hesitancy and acceptance in adult populations, with the aim of informing best practices for improving vaccination rates. All vaccine types, including HPV, seasonal influenza, tetanus, diphtheria, pertussis, and COVID-19, are considered.

Primary outcomes: effects of educational interventions on vaccination rates (vaccine uptake/coverage), and also change in intentions toward vaccination.

Secondary outcomes: capture the psychological, informational, and behavioral factors that influence those primary outcomes, together with contextual descriptors of the interventions and vaccines studied.

Risk of bias assessment: quality assessment of randomized controlled trials (RCTs) was conducted independently by two reviewers using the Cochrane Risk of Bias 2 (RoB 2) tool, which evaluates bias arising from the randomization process, deviations from intended interventions, missing outcome data, outcome measurement, and selective reporting. Observational studies were assessed using the Newcastle-Ottawa Scale (NOS), which evaluates study selection, comparability, and outcome assessment.

Certainty of evidence: the certainty of the evidence was assessed using the GRADE approach, considering the risk of bias, inconsistency, indirectness, imprecision, and publication bias for each outcome.

Statistical analysis: meta-analysis was performed using JASP version 0.19.3.0. Effect sizes (Cohen's d) were calculated, and a random-effects model was applied to account for between-study heterogeneity. All 66 eligible studies were included in the qualitative synthesis, while only 22 studies reporting sufficient quantitative data were included in the meta-analysis. Extracted data were managed and analysed using Microsoft Excel and JASP, with categorical variables coded to facilitate statistical analysis. Risk of bias across studies: heterogeneity was assessed using the I² statistic, with values >50% indicating substantial heterogeneity. Publication bias was evaluated using funnel plots and Egger's test.

Results     

After identifying all records from the database searches, duplicate records were removed. The remaining titles and abstracts were screened against the predefined eligibility criteria, and full-text articles were assessed where eligibility could not be determined from the title or abstract alone. A total of 66 studies met the inclusion criteria and were included in the qualitative synthesis (Figure 1).

Characteristics of the included studies: the review ultimately covered 66 studies comprising roughly 44,769 participants. More than half of these studies (56.07%) were conducted in the United States, underscoring the country's prominent public-health challenge of vaccine hesitancy, likely a reflection of its large population and ongoing vaccination issues. The sample also featured geographic variety, with contributions from the Middle East (Jordan, 3.03%) and several African nations (each 1.52%), demonstrating that vaccine hesitancy is a worldwide concern shaped by diverse cultural and socioeconomic contexts.

Most educational interventions were evaluated through randomized controlled trials (29.41%) and cross-sectional designs (22.06%). The interventions focused mainly on human papillomavirus (HPV) vaccines (33.33%) and COVID-19 vaccines (31.75%). Educational videos were the most common delivery method (32.86%). Approximately two-thirds of the interventions (65.71%) succeeded in lowering vaccine hesitancy, with improvements in knowledge (42.86%) and intention to vaccinate (35.71%) serving as the primary outcome measures (Table 2). Of the 66 included studies, 22 (13 RCTs and 9 observational studies) provided sufficient quantitative data for inclusion in the meta-analysis, while the remaining studies were synthesized qualitatively.

Risk of bias assessment: thirteen randomized controlled trials were assessed using the Cochrane Risk of Bias 2 (RoB 2) tool. Eleven studies (84.6%) were judged to have an overall low risk of bias, while two studies (15.4%) were rated as having some concerns, primarily because of missing outcome data. No randomized controlled trial was judged to have a high risk of bias (Annex 1). Nine observational studies were evaluated using the Newcastle-Ottawa Scale (NOS). Seven studies (77.8%) were rated as good/high methodological quality (8-9 stars), whereas two studies (22.2%) were of fair/moderate quality (6-7 stars). No observational study was classified as low quality (Annex 1).

Certainty of evidence: according to the GRADE assessment, the certainty of evidence was rated as high for behavioural outcomes (vaccine uptake/behaviour) and moderate for knowledge and vaccination intention. The certainty ratings were primarily influenced by inconsistency across intervention types, vaccine categories, and study settings, while the overall risk of bias remained low and no definitive publication bias was detected (Annex 1).

Overall effectiveness: meta-analysis of the 22 studies (13 randomized controlled trials and 9 observational studies) demonstrated a significant overall effect of educational interventions on vaccination-related outcomes (pooled estimate = 1.86; 95% CI: 1.38-2.33; p < 0.0001). However, substantial heterogeneity was observed across studies (I² = 94.5%; Q = 204.14; p < 0.0001), indicating considerable variation in intervention effects. Egger's regression test showed borderline evidence of publication bias (z = 1.95; p = 0.0513), although the result did not reach statistical significance.

Vaccine-specific findings: Table 3 displays how intervention effectiveness differed by vaccine type across both RCTs and observational studies. A mixed-effects model applied to the RCT data showed significant variation in effectiveness among vaccine categories (QM = 248.93; p < 0.0001). Every vaccine examined demonstrated a positive, statistically significant effect, confirming that educational strategies generally improve outcomes, though the size of the effect differs depending on the vaccine in question. Tdap vaccine interventions showed the largest effect (estimate = 2.83, 95% CI: 0.27-5.39; p = 0.0304), followed by HPV (estimate = 1.86, 95% CI:1.10-2.62; p < 0.0001), and influenza (estimate = 1.55, 95% CI: 1.34- 1.76; p < 0.0001). MMR vaccine interventions, while still effective, showed the smallest effect (estimate = 0.55, 95% CI:0.27-0.83; p = 0.0001). Residual heterogeneity was low (I² = 8.19%), suggesting that vaccine type explained a substantial proportion of the between-study variability.

The subgroup analysis from the cross-sectional studies from the mixed-effects model revealed significant differences in intervention effectiveness across vaccine types (QM = 63.31, p < 0.0001). All vaccine types showed positive and statistically significant effects, indicating that educational interventions were generally associated with improved outcomes across different vaccines. The influenza vaccine interventions showed the largest association (estimate = 1.59, 95% CI:0.81-2.36; p < 0.0001), followed closely by HPV (estimate = 1.39, 95% CI:0.63-2.15; p = 0.0003), and COVID-19 (estimate = 1.33, 95% CI:0.89-1.78; p < 0.0001). The similarity in the strength of association across vaccine types suggests that educational interventions may have comparable effectiveness for different vaccines in cross-sectional settings. This latter analysis also revealed low residual heterogeneity (I² = 20.37%), indicating that vaccine type accounts for a substantial portion of the variability in intervention associations.

Figure 2 shows that the mixed-effects model for the 13 RCTs revealed significant differences in intervention effectiveness across educational strategies (QM = 330.63; p < 0.0001). Interactive website interventions produced the largest estimated effect (estimate = 5.84; 95% CI: 1.53-13.21), although this was not statistically significant (p = 0.12). Among the statistically significant interventions, mobile-based (estimate = 2.37; 95% CI: 1.15-3.60; p = 0.0001) and web-based interventions (estimate = 2.19; 95% CI: 1.21-3.17; p < 0.0001) demonstrated the greatest effectiveness. Analysis of the nine observational studies also showed significant differences across intervention categories (QM = 578.85; p < 0.0001). Although social media interventions had the largest estimated association (estimate = 4.41; 95% CI: -1.68-10.50), the result was not statistically significant (p = 0.16). Questionnaire-based interventions (estimate = 2.63; 95% CI: 1.53-3.73; p < 0.001), educational sessions (estimate = 1.55; 95% CI: 0.57-2.53; p = 0.0019), and multi-component interventions (estimate = 1.53; 95% CI: 0.55-2.51; p = 0.0022) showed significant positive associations with vaccination-related outcomes.

Discussion     

The systematic review revealed a significant concentration of vaccine hesitancy studies in the United States, with over half of the research conducted there. This result highlights how vaccine hesitancy is viewed as a major public-health concern, particularly given the recent controversies over the safety and effectiveness of childhood vaccines and COVID-19 shots [13,14]. The large volume of research likely mirrors the United States' heterogeneous population, where a mix of cultural and socioeconomic influences shape attitudes toward vaccination [15], and reflects strong governmental support for public-health programs [16]. Including studies from the Middle East and Africa emphasizes that vaccine hesitancy is a worldwide phenomenon, with cultural subtleties affecting uptake [17,18], even though European nations such as Italy and the United Kingdom encounter comparable obstacles [19]. Our knowledge of vaccine resistance in Latin America and certain Asian regions remains limited because those areas are under-represented in the literature [20,21]. Closing these gaps is essential for creating culturally tailored strategies that can effectively boost vaccination rates across the globe.

Study designs in educational interventions on vaccine hesitancy: research on educational approaches to reduce vaccine hesitancy largely relies on controlled experiments, especially Randomised Controlled Trials (RCTs) [22]. While RCTs are valuable for establishing causal links, they may not fully capture the complexity of real-world settings. The frequent use of cross-sectional studies, useful for gauging current attitudes and beliefs, shows a growing interest in mapping public sentiment about vaccines [23]. Observational studies add another layer by illustrating how educational efforts translate into behavioural change across varied contexts [24]. Recognising that numbers alone cannot untangle this multifaceted issue, scholars are increasingly turning to mixed-methods and quasi-experimental designs, signaling a move toward richer, more nuanced insights [25,26]. Altogether, this methodological variety bolsters the evidence base, offering both opportunities and challenges for designing effective education programmes that curb vaccine hesitancy.

Focus on specific vaccines: a systematic review of educational interventions shows that one-third of the work (33.33%) centers on the human papillomavirus (HPV) vaccine-a logical focus given its role in preventing adolescent cancers [27]. Similarly, 31.75% of studies target COVID-19 vaccination, reflecting the urgent need for clear messaging amid widespread misinformation during the pandemic [28]. Seasonal influenza receives notable attention as well (22.22%), underscoring the importance of annual campaigns to limit flu outbreaks [29]. Combined-vaccine programmes account for 6.35% of the literature, aiming to improve public understanding of multi-dose schedules [30]. In contrast, vaccines such as MMR and Tdap receive comparatively little coverage, suggesting gaps in outreach for these essential immunisations. The predominance of COVID-19 and HPV research aligns with current public-health priorities, highlighting the necessity of tailored strategies to overcome hesitancy for these particular vaccines. Future work should explore hesitancy dynamics across a broader range of vaccine types to inform more context-specific educational efforts.

Intervention types and strategies: analysis of the interventions reveals a strong preference for educational videos, which feature in 32.86% of studies. This reflects a bias toward visually engaging formats that can simplify complex vaccine information [31,32]. Social-media-based interventions appear in 14.29% of the literature, demonstrating the reach and interactive potential of digital platforms for fostering vaccine-related dialogue [33]. Questionnaires or surveys are employed in 11.43% of projects, emphasizing the need to gauge baseline knowledge and attitudes before tailoring interventions [34]. Multimodal approaches-combining several communication channels-make up 8.57% of the work, indicating a push toward integrated outreach [35]. Community-focused peer outreach programs constitute 5.71%, underscoring the value of trusted local messengers in building vaccine confidence [36]. Overall, these trends point to a shift toward multimedia and community-driven tactics, highlighting the importance of continual innovation in how we address vaccine hesitancy [37]. Ongoing research should compare the effectiveness of these varied approaches to identify the most impactful strategies for different settings.

Measured outcomes: outcome assessment places the greatest emphasis on knowledge, evaluated in 42.86% of studies. Enhancing factual understanding is widely regarded as a cornerstone for encouraging informed vaccination choices [38]. The next most common metric is intention (35.71%) [39], reflecting the belief that willingness to vaccinate predicts actual uptake [40]. Behavioural outcomes are tracked in 25.71% of investigations, providing concrete evidence of whether educational efforts translate into real-world action [41]. Although improvements in vaccine knowledge and vaccination intention were the most frequently reported outcomes, comparatively fewer studies measured actual vaccination behaviour. This intention-behaviour gap suggests that increased knowledge or positive attitudes do not necessarily translate into vaccine uptake. Behavioural change often depends on additional structural factors, including access to vaccination services, reminder systems, appointment scheduling, healthcare provider recommendations, and social support [40-43]. Future educational programmes should therefore combine educational strategies with behavioural interventions, such as reminder systems, digital scheduling tools, and community-based follow-up, to maximize improvements in vaccine uptake.

Overall effectiveness of educational interventions (meta-analysis): the pooled analysis shows that educational programs markedly improve people's decisions about vaccination (overall effect = 1.85, p < 0.0001), underscoring their value for public-health campaigns. However, the very high heterogeneity (I² =94.5%) signals that many variables, such as the audience's characteristics, the vaccine in question, and how the intervention is designed, shape the magnitude of benefit [44]. The subgroup analyses conducted by vaccine type and intervention format substantially reduced residual heterogeneity, indicating that these study-level characteristics explained an important proportion of the between-study variability. Consequently, a single, uniform approach is unlikely to work everywhere; interventions that are customized to the cultural and contextual realities of specific groups tend to achieve stronger outcomes [36,45]. Research also indicates that culturally attuned strategies are especially potent for reducing hesitancy among underserved populations [46]. Ongoing refinement of educational tactics is therefore essential to keep them evidence-based and appropriate for the setting [47]. These insights should guide the planning and rollout of future campaigns, particularly as new public-health threats like COVID-19 emerge [48]. Confidence in these findings is strengthened by the methodological quality of the included studies. Most randomized controlled trials were judged to have a low risk of bias, while most observational studies were rated as high methodological quality. Furthermore, the GRADE assessment indicated high certainty for behavioural outcomes and moderate certainty for knowledge and vaccination intention, suggesting that the overall conclusions are supported by evidence of moderate-to-high certainty.

Publication bias considerations: funnel-plot inspection suggested possible asymmetry, while Egger's regression test demonstrated only borderline evidence of publication bias (p = 0.0513). The observed asymmetry may reflect the substantial between-study heterogeneity rather than selective publication [49,50].

Meta-analysis of randomized controlled trials (RCTs)-subgroup: when RCTs are examined separately, educational interventions remain highly effective (effect =1.48, p < 0.0001). Yet, heterogeneity remains sizable (I² =73%), reflecting differences in delivery methods, participant demographics, and content focus. Though RCTs are the gold standard for causal inference, their success can vary according to factors such as age group, cultural background, or the specificity of the educational material [51,52]. Previous evidence suggests that differences in participant characteristics, intervention delivery, and educational content contribute substantially to variability across randomized trials [20,52].

Meta-analysis of cross-sectional studies- subgroup: cross-sectional studies also report a significant positive association (effect =1.36, p < 0.0001), suggesting that education can sway vaccination decisions across diverse settings. Because cross-sectional designs cannot establish causality and may be confounded by factors such as socioeconomic status, the modest heterogeneity (I² = 20%) should be interpreted cautiously [45,53]. Nevertheless, the strong correlation reinforces the relevance of educational outreach for boosting vaccine uptake [38,48]. Incorporating longitudinal designs in future work would help clarify causal pathways and refine intervention strategies [38].

Randomized controlled trials studies subgroup analyses by vaccine type: within RCTs, the effectiveness of educational interventions varies markedly across vaccine categories (QM = 248.93, p < 0.0001). Tailored content appears crucial: for instance, Tdap education yields the largest benefit, likely because the public already recognizes its value [44]; conversely, MMR education shows a smaller effect, perhaps due to lingering myths and safety concerns [48]. These patterns underscore the need for vaccine-specific messaging to maximize impact [52,54-59]. The low residual heterogeneity (I² ͌ 8%) suggests that well-designed, targeted approaches can produce consistent gains across many vaccines [47].

Cross-sectional studies subgroup analyses by vaccine type and intervention strategy: cross-sectional analyses demonstrated that educational interventions were positively associated with vaccination-related outcomes across vaccine types (QM = 63.31, p < 0.0001). Influenza vaccine interventions showed the largest effect (effect = 1.59, p < 0.0001), likely reflecting heightened public awareness and the routine implementation of seasonal vaccination campaigns [48]. The relatively low heterogeneity (I² = 20%) suggests that educational interventions have reasonably consistent effects within vaccine categories, although differences between vaccine types indicate that intervention content should be tailored to address vaccine-specific concerns. Similarly, subgroup analyses by intervention type revealed significant differences in effectiveness (QM = 578.8525, p < 0.0001), highlighting the value of combining traditional and digital educational approaches. Although social media interventions demonstrated the largest effect estimates, these were not statistically significant, suggesting considerable variability across studies and the need for further evaluation of digital platforms [44]. Questionnaire-based interventions were among the most effective, emphasizing the importance of active participant engagement during educational programmes [47]. However, because cross-sectional studies cannot establish causal relationships and remain susceptible to unmeasured confounding, longitudinal and experimental studies are needed to confirm these findings and refine vaccine-specific educational strategies [48,60-66].

Implications for policy, practice, and research: in terms of policy, funding and research efforts should be expanded to under-studied regions such as Asia and Latin America. Governments should embed evidence-based, culturally resonant educational tactics and involve community leaders in vaccination programs for priority vaccines like HPV and COVID-19 to build trust and uptake. Furthermore, the practice implications point to the fact that multimedia tools (educational videos, social-media posts) and community engagement approaches proved effective; however, educational interventions should also be integrated with behavioural strategies such as appointment reminders, SMS prompts, digital scheduling platforms, and healthcare-provider recommendations to bridge the gap between vaccination intention and actual uptake.

Lastly, implications for future research highlight the need for longitudinal designs are needed to establish causal links between education and vaccination behaviour and to track attitude changes over time. Comparative studies should test different educational formats across vaccine types and demographic groups, especially for under-represented vaccines such as Tdap and MMR. Emerging digital platforms (mobile health apps, interactive online tools) warrant investigation for their potential to boost vaccine education and acceptance.

Limitations of the review: this review included studies on multiple vaccine types across diverse populations, which may limit the applicability of the findings to individual vaccine contexts. Only English-language studies indexed in the selected databases (PubMed, Scopus, Google Scholar, and PsycINFO) were included, potentially excluding relevant grey literature and non-English publications. The substantial heterogeneity observed across studies reflected differences in study designs, populations, interventions, outcome measures, and data collection methods, which limited quantitative pooling and subgroup comparisons. In addition, the evidence base was dominated by studies conducted in the United States and Europe and included a higher proportion of female participants, which may reduce the generalizability of the findings to other regions and populations.

Conclusion     

Educational interventions are effective in improving vaccination-related outcomes, although their effectiveness varies according to intervention type and vaccine category. Multi-component and tailored educational strategies generally demonstrated greater effectiveness than single-format approaches, while vaccine-specific interventions produced different effect sizes across vaccines. The substantial heterogeneity observed was largely explained by differences in intervention design, vaccine type, study populations, and study design. These findings support the use of evidence-based, culturally appropriate educational strategies to improve vaccine uptake. Future research should prioritize longitudinal evaluations, comparative studies across vaccine types, and the integration of behavioural strategies with educational interventions to achieve sustained improvements in vaccination uptake.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Oluwaseun Omotola Omoyele conceived and designed the study; Oluwaseun Omotola Omoyele and Daprim Samuel Ogaji conducted the literature search, data extraction, and analysis; Oluwaseun Omotola Omoyele drafted the initial manuscript; Daprim Samuel Ogaji and Olufemi Martins Adesope critically reviewed and revised the manuscript for important intellectual content. All authors contributed to the interpretation of findings, agreed to be accountable for all aspects of the work, and read and approved the final version of this manuscript.

Tables and figures     

Table 1: search strategy and study selection criteria for the systematic review from January, 2012 to August, 2024

Table 2: distribution of study characteristics based on search strategy results on educational interventions for vaccine hesitancy (total number of studies n = 66) from January, 2012 to August, 2024

Table 3: quantitative effects of educational interventions on vaccine-related outcomes, stratified by vaccine type and study design (randomised controlled trials (RCTs) (n=20 studies) and cross-sectional studies (n=15 studies)) from January, 2012 to August, 2024

Figure 1: PRISMA flow diagram illustrating the study selection process for the systematic review of educational interventions targeting vaccine hesitancy from January, 2012 to August, 2024

Figure 2: (A,B) forest-plot comparison of the effectiveness of educational interventions on vaccine-related decision-making outcomes, stratified by study design from January, 2012 to August, 2024

Annex     

Annex 1: supplementary materials (PDF KB)

References