Beyond Access: A Mixed-Methods Analysis of the Proximity Paradox and Immunization Inequities Sustaining Zero-Dose Children in Cameroon

Technical Summary: Beyond Access: A Mixed-Methods Analysis of the Proximity Paradox and Immunization Inequities Sustaining Zero-Dose Children in Cameroon

Problem Statement
Despite the global "Big Catch-Up" (BCU) initiative aimed at restoring routine immunization coverage following the disruptions of the COVID-19 pandemic and armed conflict, Cameroon continues to face a critical burden of zero-dose (ZD) and under-immunized (UI) children. While geographic proximity to health facilities is often assumed to correlate with service utilization, this study identifies a "proximity paradox" where caregivers living closest to facilities experience high rates of service refusal. The research addresses a gap in primary literature regarding the specific structural, socio-behavioral, and policy-level barriers that sustain immunization inequities among vulnerable populations, even when physical access is available. The study seeks to inform the sustainable institutionalization of the BCU strategy by moving beyond temporary, campaign-style responses to understand the systemic determinants of missed opportunities.

Methodology
The study employed a cross-sectional, mixed-methods multiple-case design conducted between July and August 2025. The research was grounded in a multidimensional conceptual framework analyzing three intersecting domains: supply-side constraints, socio-behavioral determinants, and macro-level policy/financing pathways.

• Study Settings: Four purposively selected health districts representing distinct vulnerability archetypes were chosen: Cité Verte (urban slums), Kumba South (armed conflict), Manoka (remote maritime island), and Mokolo (isolated rural area).
• Quantitative Component: A household survey was administered to 264 caregivers of ZD and UI children (aged 12–59 months). The sample was derived from a target of 300, adjusted for non-response, using a pre-tested quadrant sampling approach. Data were collected via KoboCollect and analyzed using descriptive statistics in R software.
• Qualitative Component: Data were gathered through 37 Key Informant Interviews (KIIs) with stakeholders across all health system levels and 11 Focus Group Discussions (FGDs) involving 86 community stakeholders (including Community Health Workers and caregivers). Interviews were audio-recorded, transcribed, and analyzed using thematic analysis with a hybrid inductive-deductive coding approach.
• Triangulation: Findings from the surveys, qualitative narratives, and secondary data (DHIS2, EPI dashboards, policy documents) were iteratively triangulated to validate conclusions.

Key Results
The study reveals a stark disconnect between perceived access and actual service delivery, characterized by the following findings:

1. The Proximity Paradox: While 76% of caregivers reported easy physical access to services, 25% (66/264) reported being "turned away" from facilities. Counterintuitively, caregivers living closest to facilities (≤15 minutes) experienced the highest refusal rates (34%), compared to 18% for those 16–30 minutes away. This suggests that reliance on fixed-site facilities, which often suffer from stockouts and rigid multi-dose vial policies, creates higher missed opportunities than mobile outreach in more remote or conflict-affected areas.
2. Supply-Side Barriers: The primary drivers of facility turn-aways were vaccine stockouts, rigid scheduling, and strict multi-dose vial policies (refusing to open vials for small numbers of children). Additionally, qualitative data revealed instances of illegal informal payments for free services, which eroded community trust.
3. Socio-Behavioral Determinants: Despite high general awareness (98% knew where to get vaccinated) and belief in vaccine importance (97%), vaccine hesitancy was driven primarily by fear of Adverse Events Following Immunization (AEFI) (55%) and circulating rumors (25%). Only 10% cited poor physical access as a primary barrier. In conflict-affected zones, hesitancy was deeply intertwined with political mistrust and a boycott of state-sponsored interventions.
4. Policy and Financing Fragility: The BCU initiative successfully utilized proactive "Catch and Vaccinate" outreach models to bypass facility friction. However, the long-term institutionalization of these models is threatened by an impending "fiscal cliff" as donor funding (e.g., Gavi) tapers off. The study highlights a lack of domestic financing for Community Health Worker (CHW) stipends and high-cost logistics. Furthermore, the use of parallel digital tracking platforms (e.g., IASO) alongside national systems (DHIS2) created structural fragmentation and double-reporting burdens, delaying data reconciliation.

Key Contributions

• Empirical Evidence of the Proximity Paradox: The study provides quantitative evidence that geographic proximity does not guarantee immunization coverage, identifying facility-level operational rigidities (stockouts, vial policies) as the primary drivers of exclusion for those living nearest to clinics.
• Differentiation of Barriers by Context: The research demonstrates that while urban and fixed-site settings suffer from supply-side rigidity, conflict-affected and remote areas benefit from adaptable mobile outreach, yet face unique challenges related to political mistrust and security.
• Identification of Systemic Fragility: The paper documents the specific risks of transitioning from donor-funded vertical campaigns to routine horizontal primary care, specifically highlighting the "fiscal cliff" for CHW financing and the inefficiencies caused by fragmented digital health information systems.
• Operational Insights for Policy: By analyzing the intersection of supply-side failures and socio-behavioral fears, the study offers a nuanced view of why "catch-up" strategies succeed in some contexts but fail to sustain coverage without structural reform.

Significance and Claims
The paper claims that resolving immunization inequities in Cameroon requires moving beyond the assumption that geographic access is sufficient. The authors argue that achieving the Immunization Agenda 2030 targets necessitates dismantling intersecting operational and socio-behavioral barriers.

The study asserts that the temporary success of the BCU initiative is unsustainable without urgent domestic financial investment to support proactive outreach models and the structural harmonization of digital health systems. The authors conclude that transitioning from donor-reliant emergency responses to resilient routine primary care is the only viable pathway to prevent coverage backsliding and ensure that no child is left behind. The findings are intended to provide policymakers with actionable evidence to navigate the fiscal transition and institutionalize community-adapted delivery models.