Community Engagement in Vaccination Promotion: Systematic Review and Meta-Analysis

"Community engagement drives interventions operated in a bottom-up manner rather than the traditional top-down approach. This approach supports stakeholders coming together to achieve global vaccination coverage goals from childhood to adulthood."

Community engagement is a process that involves engaging and motivating diverse partners to collaborate in harnessing community potential and enhancing community health. This process can play a vital role in global immunisation strategies, offering the potential to overcome vaccination hesitancy and enhance vaccination confidence. However, the evidence supporting its effectiveness in vaccination promotion is fragmented and of uncertain quality. Thus, this review aimed to systematically examine the effectiveness of different contents and extent of community engagement for promoting vaccination.

In June 2022 and April 2023, the researchers conducted literature searches in 4 English databases (PubMed, Embase, Web of Science, and Cochrane Library) and 2 Chinese databases (CNKI and Wan Fang) to identify relevant articles. Original research articles applying an experimental study design that investigated the effectiveness of community engagement in vaccination promotion were eligible for inclusion. Each study was assessed and categorised as having low, moderate, or high risk of bias.

Twenty articles of 11,404 records from 2006 to 2021 were selected. The included studies used various designs: 12 applied single-group pre-post study designs, 5 were cluster randomised controlled trials (RCTs), and 3 were non-RCTs. These studies focused multiple vaccines, with 8 focusing on children's immunisation, 8 on human papillomavirus (HPV) vaccine, 3 on hepatitis B virus vaccine, and 1 on COVID-19 vaccine.

Community engagement does not neatly fit into predefined typologies, as it encompasses a variety of contexts, extents, and outcomes. To address this complexity, the contents of community engagement were delineated into 4 main categories: participant recruitment, intervention development, intervention implementation, and data collection. Community engagement took various forms of intervention strategies, including social marketing campaigns, community mobilisation, health education and discussions, health service support, and follow-up and reminders. These interventions were often combined into intervention packages.

The extents of community engagement were categorised as low, moderate, and high: A low extent of community engagement indicated that studies fulfilled 1 or 2 contents of community engagement; a moderate extent of community engagement indicated that studies fulfilled 3 contents of community engagement; and a high extent of community engagement indicated that studies fulfilled all 4 contents of community engagement. Most studies incorporated 2 engagement contents, with the majority engaged in intervention implementation (19/20, 95%) and intervention development (13/20, 65%), followed by participant recruitment (12/20,60%) and outcome evaluation (11/20, 55%). Furthermore, most studies fell into the moderate engagement extent category (n=10), followed by low engagement extent (n=7) and high engagement extent (n=3).

The pooled meta-analysis incorporated usable data from 21 intervention groups across 20 studies. The meta-analysis revealed:

• There were significant increases in vaccination rates both in pre-post comparison (rate difference [RD] 0.34, 95% confidence interval [CI] 0.21-0.47, I2=99.9%, P<.001) and between-group comparison (RD 0.18, 95% CI 0.07-0.29, I2=98.4%, P<.001). In other words, community engagement strategies resulted in a 34% increase in vaccination rates through a pre-post intervention effect analysis and an 18% increase in vaccination rates through a between-group intervention effect analysis.
• Participant recruitment, one of the 4 main types of community engagement, had the largest effect size (RD 0.51, 95% CI 0.36-0.67, I2=99.9%, P<.001), followed by intervention development (RD 0.36, 95% CI 0.23-0.50, I2=100.0%, P<.001), intervention implementation (RD 0.35, 95% CI 0.22-0.47, I2=99.8%, P<.001), and data collection (RD 0.34, 95% CI 0.19-0.50, I2=99.8%, P<.001). One implication: Community partners who possess the knowledge and skills to effectively approach the priority population and actively engage in participant recruitment hold the most potential to achieve relatively high recruitment and retention rates for participants.
• High community engagement extent yielded the largest effect size (RD 0.49, 95% CI 0.17-0.82, I2=100.0%, P<.001), followed by moderate community engagement extent (RD 0.45, 95% CI 0.33-0.58, I2=99.6%, P<.001) and low community engagement extent (RD 0.15, 95% CI 0.05-0.25, I2=99.2%, P<.001).
• "Health service support" (e.g., free vaccination, vaccination outreach or mobile clinic vaccination, and flexible vaccination schedules) demonstrated the largest effect sizes (RD 0.45, 95% CI 0.25-0.65, I2=99.9%, P<.001), followed by "health education and discussion" (RD 0.39, 95% CI 0.20-0.58, I2=99.7%, P<.001), "follow-up and reminder" (RD 0.33, 95% CI 0.23-0.42, I2=99.3%, P<.001), and "social marketing campaigns and community mobilisation" (RD 0.24, 95% CI 0.06-0.41, I2=99.9%, P<.001).

No discernible signs of publication bias were detected either in the pre-post or in the between-group intervention effect analyses (P=.25), and evidence quality in the meta-analysis was graded as moderate in both the pre-post and between-group intervention effect analyses.

In discussing the findings, the researchers observe that the effects of community engagement on vaccination promotion in the included studies did not occur as a linear progression but, rather, consisted of complex processes influenced by facilitators or challenges:

• At the individual level, the sense of confidence and ownership, along with the development of leadership skills and knowledge, facilitated community partners to engage with participatory processes. Conversely, the lack of interest and capacity, as well as the ambiguity of role and responsibility, challenged community partners to engage with participatory processes.
• At the community level, trust facilitated effective community engagement, while mistrust inhibited genuine community engagement.

Among the suggestions for future work outlined in the paper:

• Studies should adopt a broader range of study designs that encompass both quantitative and qualitative methodologies to measure intangible facilitators or challenges in the area of community engagement.
• "Community engagement functions as a dynamic process rather than as a discrete intervention, implying that evaluation should fully account for intrinsic complexities rather than simply focusing on outcome indicators. The primary studies should conduct thorough process evaluations to incorporate a spectrum of outcome measures and complement qualitative evaluations to elucidate the active ingredients of community engagement and the potential unintended effects of community engagement."
• Future work should focus on intervention theories, logic models, and outcome frameworks so as to assess multidimensional community-level outcomes of community engagement, thereby going beyond a framing of the effectiveness of community engagement in terms of short-term, individual-level outcomes. "The interaction between the engagement strategy and the community system creates a degree of complexity beyond the detail of intervention implementation....This complexity grows in concert with the delivery of the engagement strategy, which may, in some instances, reshape the intervention and the community context..."
• Future studies should incorporate economic analysis to explore the potential cost-utility and cost-effectiveness of community engagement in real-world contexts. "While studies support the value of community engagement, the evaluation of community engagement has largely focused on health outcomes and ignored economic information."
• "While there is a vast body of literature on community engagement spanning various disciplines, comprehensive guidelines and frameworks for community engagement are lacking. The adoption of consistent guidelines and frameworks can formalize the implementation and evaluation of community engagement efforts."

In conclusion: "The results of this meta-analysis supported the effectiveness of community engagement in vaccination promotion with variations in terms of engagement contents and extent. Community engagement required a 'fit-for-purpose' approach rather than a 'one-size-fits-all' approach to maximize the effectiveness of vaccine promotion."