Effects of local faith-actor engagement in the uptake and coverage of immunization in low- and middle-income countries: A literature review

Introduction: Religious leaders are universally recognized as having an influence on immunization uptake and coverage in lowand middle-income countries (LMICs). Despite this, there is limited understanding of three questions: 1) how do religious leaders impact the uptake and coverage of immunization in LMICs? 2) what successful strategies exist for working with local faith actors to improve immunization acceptance? and 3) what evidence gaps exist in relation to faith engagement and


Introduction
Religious leaders and local faith actors are universally recognized as having an influence on immunization uptake and coverage in low-and middle-income countries (LMICs). 1,2 This association between religion and vaccination dates back to as early as 1,000 AD, when a Buddhist nun was described as grinding scabs from a smallpoxinfected person into a powder, blowing it into a nonimmune person's nostrils to induce immunity. [3][4][5] Today, many major religions commonly believe that vaccination-the act of administering a substance that stimulates the body's immune response against diseases-supports their shared objectives of preserving and protecting life, health, well-being, equity, and prevention of suffering, especially among children and other innocents. 5 Some religions even call for vaccination as a moral imperative to preserve the lives of children or within a community. 3,6 Yet, despite the powerful positive potential to reduce and eliminate diseases such as smallpox and polio, religious factors remain the third most frequently cited reason for vaccine hesitancy in global surveys. [7][8][9][10][11][12][13] Vaccine hesitancy in this case is defined as delay in acceptance or refusal of vaccines despite the availability of vaccination services. Religiously-linked, vaccine hesitancy concerns are especially pronounced and rising in LMICs, though often these concerns are inter-mixed with others related to political, economic, or social issues. [13][14][15] Prominent media coverage and academic study of widespread polio vaccine hesitancy among Muslim communities in Northern Nigeria and Pakistan in the 2000s and 2010s has further heightened awareness and interest in vaccine hesitancy and faith communities.

Specific aims of the literature review
There is still limited information on and understanding of how faith actors impact the uptake and coverage of immunizations in LMICs, as well as what interventions work to counter vaccine hesitancy among local faith actors. To date, the bulk of research on vaccine hesitancy and faith communities has been conducted in high-income countries. We are unaware of efforts to validate vaccine hesitancy measurement tools in sub-Saharan Africa. 16 This is a critical evidence gap, as vaccine hesitancy among faith communities has been demonstrated to negatively impact immunization coverage in certain LMICs. 17 The rollout of COVID-19 vaccinations in LMICs also represents an acute challenge and opportunity to engage faith leaders in what will be the largest public health vaccination campaign in the past 100 years.
The Faith Engagement Team of the US Agency for International Development's (USAID's) MOMENTUM Country and Global Leadership program undertook a study of the role of faith communities in vaccine hesitancy. In January 2021, May 2022. Christian Journal for Global Health 9 (1) we conducted a literature review to answer three key questions: 1) How do religious leaders and faithbased organizations impact the uptake and coverage of immunization in LMICs? 2) What successful strategies exist for working with local faith actors and communities to improve immunization acceptance and reduce vaccine hesitancy? and 3) What evidence gaps exist in relation to faith engagement and immunization? Findings will advance understanding on how to more effectively engage local faith actors in promoting routine and supplementary immunization campaigns and reducing vaccine hesitancy.

Search strategy
The research team searched PubMed and Google Scholar databases for peer-reviewed literature for the period from January 1, 2011 to January 15, 2021 with key search terms related to faith engagement and immunization ( Figure 1). Figure 1. Literature review search terms We combined the following terms: vaccin*, immuniz*, immunis*, vaccine hesitancy AND faith, faith-based, faith actors, relig*, church, mosque, temple, Christian, Muslim, Islam, Hindu, Buddhis* AND Low-and Middle-Income Countries, LMICs, Africa, Asia, Latin America. Note. The asterisk* indicates a wildcard symbol enabling a broader search by finding words that start with the same letters/word stems.
We supplemented the peer-reviewed database searches with a gray literature search, recognizing that many interventions related to religious leaders are not published in peer-reviewed journals. The review included a keyword search across several online databases and organizational websites for the same period: Google, the Vaccine Confidence Project Literature Archive, and USAID's Maternal and Child Survival Program website. References in papers meeting inclusion criteria were searched for further relevant studies for potential review. The authors also solicited submissions from a cohort of key informants who included experts from the USAID MOMENTUM Country and Global Leadership program and from a cohort of 18 global faith engagement and immunization experts drawn from Christian Connections for International Health's (CCIH) networks.

Inclusion/exclusion criteria
We included peer-reviewed studies and gray resources meeting the following criteria: 1) the study context was an LMIC; 2) it included any of the search keywords in the title or abstract; 3) the main focus of the study or resource was related to faithactor engagement and immunization and/or vaccine hesitancy; 4) it was published between January 1, 2011 and January 15, 2021; and 5) it was published in English. Resources were excluded if they were about faith engagement and immunization in highincome countries, news articles, online blogs, or references to social media postings.
As depicted in Figure 2, the literature review found an initial 434 articles through initial search terms and an assessment of relevance using the preidentified inclusion criteria. All articles that met the inclusion criteria (137) were included for quality assessment and data extraction. Of these, 27 duplicate references were manually removed, leaving 110 resources. These are presented in Appendix 1.

Data extraction and analysis
We reviewed the 110 relevant papers and entered qualitative and quantitative descriptive information into an Excel data extraction matrix template that included the following categories: author, year, publication; country(ies), and/or region covered; type of study/article/resource; focal religion(s); and topical area of focus (including vaccine hesitancy, specific types of vaccine). The matrix also captured key observations and findings, vaccine hesitancy findings, evidence-based interventions related to engaging local faith actors and immunization, promising practices for faith engagement and immunization, and reported evidence gaps. Data were coded using a predefined set of themes and sub-themes from the matrix categories to answer the three literature review questions.

Description of the resources reviewed
Despite results, there is still scant published evidence of the role of religion and local faith actors on immunization. 1 Most studies treat religion as a confounding variable without a detailed examination of the nuanced impact or inter-related factors (social/political/economic) that impact immunization uptake. 1,2 The review did find a number of key thematic foci, as depicted in Table 1.  May 2022. Christian Journal for Global Health 9(1)

Religion of Focus in Relation to Immunization Exploration
Multiple religions or no specific religion Akseer, N (2018); Bangura JB (2020)

Study/resource type and quality
The review found a total of 110 relevant articles, 69% of which were peer reviewed, and the other 31% were from gray literature. While the literature review did not explicitly assess and score study quality, the quality of literature reviewed appears mixed based upon the study designs found. Most peer-reviewed literature cited was observational in nature; gray literature or discussion papers represented 44.5% of resources reviewed. The review found only three intervention studies (2.7%) examining approaches for engaging faith leaders. As the dominant resource type, the descriptive literature consisted of cross-sectional studies, qualitative studies, mixed methods, and data analysis. Additionally, there were several comment-aries and discussion papers along with both literature and systematic reviews. The gray literature consisted of tools, guidelines, various resources, and reports. There were a variety of additional gray resources found including books, evaluations, poster/oral presentations, and unpublished theses.

Topical focus
The relevant literature was predominantly focused on vaccine hesitancy (60%) among different faith groups, versus a general exploration of religious engagement and vaccines (36%). The remaining 4% of resources focused on new vaccine acceptance among local faith actors and vaccines delivered by local faith actors in humanitarian environments. Of the articles that examined a specific vaccine type, there was a focus on campaign-based vaccinations and so-called "controversial" vaccines (those causing hesitancy), rather than routine immunizations. The resource breakdown included: • Polio (20) • Human papillomavirus (HPV) (9)

Time period
At least five articles have been published every year since 2012 on the topic of local faith actors and immunization in LMICs. Interest in the topic appear to be rising as 70% of the resources identified were published within the last five years of the review (2016)(2017)(2018)(2019)(2020). Last year (2020) was the peak, with 20 articles published.

Religions of focus
Just under half the resources found (42%) focused on multiple religions or general local faithactor engagement and immunization rather than specific religions. The majority of studies with an explicit religious focus examined large-scale organized, monotheistic faiths (Islam, Christianity), and mainline religions-those linked to established denominations in the global North. Only eight studies explored immunization and faith engagement in traditional, folk, or growing non-networked religions such as Pentecostal or Charismatic denominations (12.5%), a growing proportion of religions in LMICs. We found few studies exploring immunization in the context of Buddhist or Hindu faiths in Asia.
The literature also reflects a heavy focus on polio vaccine hesitancy among Muslim populations, with 19% of all resources focused on that topic. The hesitancy literature in general focuses primarily on countries with large or predominantly Muslim populations, with the exception of Apostolic Christian denominations within Zimbabwe.

Geographic focus
Nearly half of the studies that met the inclusion criteria (44%) offered a global or multi-country focus in LMICs, rather than zeroing in on a specific geographic area. The other resources were localized to specific regions, predominantly sub-Saharan Africa (34%), followed by Southeast and South Asia (19%). Within sub-Saharan Africa, the majority of resources focused on Nigeria (16 articles), with fewer resources from Ethiopia, Kenya, Uganda, Tanzania, Zambia, and Zimbabwe ( Figure 3).  (1) Within the Southeast and South Asian region, the majority of resources were specific to Pakistan (12 articles), while Afghanistan, Bangladesh, India, Indonesia, and Malaysia had fewer published research resources. The literature review uncovered major research gaps for the Latin American and Caribbean region, and only three resources were found for the Middle East and North Africa. There were no articles published for Eastern Europe nor the Asia Pacific region.

Question 1: How do religious leaders and faith-based organizations impact the uptake and coverage of immunization in LMICs?
Measuring the precise impact and causality of local faith actors on immunization rates is challenging. Most studies generally treat religion as a confounding variable without a detailed examination of the nuanced impact or inter-related factors (social/political/economic) that effect immunization uptake. 1,2 This remains an important area for future research and exploration.
The reviewed literature did demonstrate four main mechanisms through which religious leaders and faith actors impact immunization uptake in LMICs: 1) influencing caretaker beliefs and values, 1,2,17,18 2) impacting access to resources that facilitate immunization uptake, 1 3) communicating immunization messages and conducting mobilization, 2 and 4) providing routine immunizations in hard-to-reach areas or humanitarian settings. These findings suggest that continued investment in and engagement with faith leaders can be a valuable strategy for immunization programming. 2,19 At the same time, the review did not find detailed explorations and analysis of the dynamics and mechanisms of how faith actors specifically influenced immunization uptake and coverage within local communities. This may warrant additional research in this area to unpack the influence and interplay of local faith actors within communities to better understand these mechanisms and design evidence-based interventions.

Religiously-linked vaccine hesitancy
Vaccine hesitancy is a complex phenomenon. Few religious groups or their sacred texts explicitly reject immunization ( Figure 4). 3,5,11,12,20,21  Multiple resources reviewed suggested that vaccination hesitancy is often cloaked under the guise of "religion," without a theologicallygrounded objection. 3,12 Instead, religious objections to vaccination serve as a cover or proxy for concerns about safety, social norms, socio-cultural issues, political, and economic factors. 2,3,5,26,27 Common faith-linked vaccine hesitancy views across religions included the belief(s) that: • Humans should not attempt to override God's will with man-made solutions. 3,4,28 • God created a perfect world, including a perfect immune system: humanity should not attempt to improve on it. 4

•
The human body is a temple of Godimmunizations introduce potentially harmful viruses, bacteria, and/or derivatives of forbidden substances. 4 • Violations against taking life, including the use of fetal tissue from abortions, which are used in the development of cell lines used to make certain vaccines. 4,21 • Violation of dietary laws (such as using vaccine development materials with porcine or bovine origins). 3 The review found additional vaccine hesitancy themes, including: promotion of faith healers and/or the power of prayer over the use of vaccines or medicine, 11,29,30 distrust of Western medicine/fear that vaccines are being tested on their community, 29,30 worry that vaccines will sterilize recipients/impact fertility, and the promotion of traditional remedies rather than biomedical solutions. 8,30,31 While these vaccine hesitancy themes were explored in numerous resources in the review, we did not find systematic analysis or study of the specific actions that local faith actors took to translate these beliefs into action and influence social norms, outside of specific references to case studies of vaccine hesitancy in certain countries among local faith actors. In these specific country examples, actions taken by local faith actors included sharing anti-vaccine messaging within houses of worship; disseminating anti-vaccination messaging informally within the community outside religious structures; broadcasting anti-vaccine messaging on mass media channels; and establishing formal or informal boycotts and encouraging adherents to avoid immunizing their children.

Heavy emphasis on Islam and vaccine hesitancy
The literature review found extensive documentation and exploration of Islam and vaccine hesitancy in LMICs, amounting to 69% of all studies with a specific single religion focus. This is likely due, in part, to very visible cases of vaccine hesitancy and boycotts in the early 2000s in northern Nigeria, Pakistan, and Afghanistan as well as the finding that Muslim religious leaders are especially influential in impacting vaccine uptake and hesitancy. 32,33 Several references underscore the principle that Islamic theology generally supports immunization, 14,22,23 and there are predominantly Muslim countries with low rates of reported vaccine hesitancy, including Bangladesh, Malaysia, Niger, and Saudi Arabia. The review did find multiple studies that suggested lower coverage of immunizations among Muslim populations in LMICs (across countries and within countries of heterogenous religions). 1,[14][15][16]34 Major drivers of vaccine hesitancy among Muslim faith communities identified in the studies included concerns that vaccines may contain haram materials (those prohibited under Islamic law) , 14,33,35 fears that immunization would impact the fertility of recipients, 32,36 and beliefs that vaccinations were part of a Western conspiracy to harm their population. 29,30 Other religions of interest Christian denominations accounted for 23% of all resources with a single religious focus in the literature review, with a strong focus on Apostolic denominations in Zimbabwe and Southern Africa. Originating from the Protestant Pentecostal church, Apostolic churches reflect a desire to emulate firstcentury Christianity in its faith, practices, and government and have historically objected to most medical interventions in lieu of prayer for healing. 9,11 Multiple studies showed lower basic immunization uptake and completion in Zimbabwe among Apostolic communities, with varying attitudes and degrees of refusal toward immunization among subsects, indicating a need for further study and interventions to address this growing population in Southern Africa. 8,9,11,20,37 Despite much coverage in news media and popular culture focused on the use of cells from aborted fetuses to develop vaccines, the review only found two resources meeting inclusion criteria focused on vaccine hesitancy among Catholic populations where Catholic bishops in Kenya led a call for the boycott of the maternal tetanus toxoid (fertility concerns) and childhood polio vaccines (safety concerns). 29,38 Vaccines of concern to faith actors Religiously-linked polio vaccine hesitancy featured most prominently within the literature (representing 20 articles/41.7% of all articles with a specific vaccine focus), with examples from Pakistan, 32,35,39,40 Nigeria, [41][42][43] and Kenya. 38 This hesitancy contributed to increased reported caretaker vaccine refusal in Kenya due to safety concerns. 38 Polio vaccine rejection by religious and community leaders was linked with overall reduced polio vaccine coverage in Nigeria. 41,43 In Pakistan, multiple barriers were found, including concerns that vaccines include non-halal ingredients 35 and fears of a Western plot to sterilize Muslims or reduce the Muslim population. 32,39 HPV immunization was found to be the second most frequently cited vaccine with religious objections. The HPV vaccine creates faith-linked challenges in both higher-and lower-income countries due to its perceived links to sexual activity.

Question 2. What successful strategies exist for working with local faith actors and communities to improve immunization acceptance and reduce vaccine hesitancy?
The literature review found limited highquality evidence and examples of specific approaches for engaging local faith actors to strengthen routine immunization and campaignbased immunization uptake. Most interventions involved engaging religious leaders and the local community in dialogue-based interventions 50 and engaging religious leaders and church structures in social mobilization and advocacy. 1,2,44,49,[51][52][53]

Improving immunization uptake and coverage
One study found that working with religious leaders on a multi-pronged immunization promotion and delivery strategy, including targeting priority populations and increasing service delivery availability, was more effective for increasing vaccine uptake than messaging with religious leaders alone. 50 Using church infrastructure, faith-based health facilities, and religious rituals as vaccination messaging or delivery points, including in humanitarian settings, was also found to be effective for increasing vaccine coverage. 19,28,54 Reducing religiously-linked vaccine hesitancy The review found limited examples of evidence-based approaches for tackling faith-linked May 2022. Christian Journal for Global Health 9(1) vaccine hesitancy. Engaging faith-based organizations and faith leaders in the rollout of new vaccines was found in multiple studies to be important for increasing community acceptability and uptake and preventing potential vaccine hesitancy. [55][56][57] Several studies found that religious concerns focused on the bioethics of vaccine production may be effectively addressed through theological analyses of sacred text and dialogue with faith leaders, including understanding the alternatives among available vaccines. 25,55,58 In Muslim countries, where there is concern that vaccines were manufactured with haram (forbidden) materials, acknowledging these concerns and communicating effectively about them with Muslim faith leaders and structures is critical. 14,59

Question 3. What evidence gaps exist in relation to faith engagement and immunization?
The literature review found promising evidence of the value of religious engagement for immunization promotion and acceptance in LMICs across faiths. In particular, we found multiple articles demonstrating the value of religious engagement for immunization promotion and acceptance, 2,16, 60 studies of vaccine hesitancy among Muslim leaders, 32,33,35,36,40,41 comparisons of immunization among different faiths within the same countries, 14,15,34 and reviews and discussion papers on the correlation between faith engagement and vaccine acceptance. 1,2,17,18 Despite these findings, this literature review found significant evidence gaps-described below-that limit the generalizability of some findings, such as: • A dearth of peer-reviewed research and gray literature on the influence of local faith actors on vaccine hesitancy in LMICs as compared to high-income countries. 16 • Low-quality evidence of impact of religious leaders' engagement on uptake of vaccines and the relative contribution of faith actors in vaccine uptake. 2 • Few studies or resources examined or evaluated the effectiveness of specific interventions with local faith actors and immunization and/or vaccine hesitancy. As a result, there is a lack of widely shared knowledge of what works (or doesn't) and successful models for engaging local faith actors. We found few published articles or gray literature that included the voices of local faith actors as primary authors or significant contributors discussing their role within immunization programs, indicating a need for further dialogue and research in this area.

Limitations
It is well-known that many local faith-based organizations and actors maintain practice-based knowledge and are less likely to publish their findings in journals. This literature review and its conclusions may therefore be subject to publication bias, in that unsuccessful interventions may be less likely to be documented in either the peer-reviewed or gray literature. In addition, the review excluded non-English language resources, potentially missing observations and promising practices.
Several other factors also warrant caution on extrapolating findings more broadly. While the literature did not explicitly assess and score study quality, the quality of literature remains mixed, based upon review of study/resource type, limiting generalizability and rigor of conclusions. As noted above, the review found evidence gaps among certain geographies, religion types, and different vaccines.
Finally, this literature was conducted amid the early launch and rollout of COVID-19 vaccination (January 2021). As such, the review found very limited and explicit gray or peer-reviewed literature on the topic of faith engagement and COVID-19 immunization. While many of the findings and interventions may be applicable and effective if applied to COVID-19 immunizations, further study and investigation is warranted for this urgent public health crisis.

Conclusions
Our literature review findings suggest that continued investment in and engagement with local faith actors can be a valuable strategy for immunization programming in LMICs. The review found that engaged religious leaders have long contributed to achieving full immunization coverage within their communities and today offer the potential to help counter growing vaccine hesitancy in some LMICs. At the same time, the review found numerous troubling examples of religiously-linked vaccine hesitancy, some well-known, such as Indonesia, Nigeria, and Pakistan, and some lesserknown examples in Burkina Faso, Chad, and Sudan.
More investigations and evidence are needed regarding what interventions that involve local faith actors are most effective, and in which contexts, in promoting vaccine uptake. Vaccine hesitancy is a highly complex phenomenon. The current peerreviewed and gray literature does not provide an adaptable, concise roadmap for tackling these issues in different geographic, cultural, linguistic, and other contexts. In particular, further study is needed on the role of faith leaders in the promotion of routine immunization (rather than campaign-based immunization), the impact of local faith actors on vaccine uptake among growing Pentecostal, Charismatic, and so-called "un-networked" faiths, and vaccine hesitancy among Buddhist and Hindu faiths in Asia.
Multiple studies and resources within the review did identify the importance of listening, understanding, and diagnosing some of the complex and inter-related socio-cultural factors that contribute to religiously-linked vaccine hesitancy. These review findings should reinforce an important caution for public health planners, policymakers, and implementers to avoid the temptation to oversimplify or blame faith actors for vaccine hesitancy. Evidence repeatedly demonstrates that apparent faith-based objections are sometimes a convenient proxy for more complex, inter-related socio-cultural, and political issues related to immunization. In cases where vaccine hesitancy is identified among local faith actors, the review suggests that listening and dialoguing with faith leaders is critical to finding theologically-acceptable solutions to vaccine hesitancy.
In addition, this review suggests that more work is needed to foster global and national-level discussions to engage faith leaders in vaccine hesitancy reduction efforts. Country-level strategies to stimulate research and dialogue with religious structures, interfaith networks, and theological institutions may help identify some of these underlying socio-cultural and political issues. To increase understanding and scale-up of successful strategies, we also encourage local faith actors and implementers to more widely share their experiences engaging religious leaders in immunization programs, which are largely absent from peerreviewed and gray literature.
This review comes at a critical time, given the rollout of COVID-19 vaccination in LMICs. At the time of the literature review, most COVID-19 vaccine hesitancy research in LMICs was just getting underway. However, emerging research in six countries shows that endorsement of the COVID-19 vaccine by faith leaders will be critical to vaccine acceptance. 61