A Methodological Framework for Assessing Cold Chain Integrity and Measles Vaccine Seroconversion in Remote Angolan Health Facilities (2021–2026)

This methodology article presents a comprehensive framework for assessing vaccine cold chain integrity and its direct impact on measles vaccine seroconversion in remote Angolan health facilities. The persistent challenge of suboptimal vaccine efficacy in low-resource settings, often attributable to cold chain failures, necessitates robust, context-specific evaluation tools. Our mixed-methods approach, implemented from 2021 to 2026, integrates quantitative and qualitative components to ensure analytical rigour. Continuous temperature monitoring using wireless data loggers across the entire supply chain is combined with serological testing of infant cohorts pre- and post-vaccination. These data are triangulated with structured observations and interviews with healthcare workers to capture operational realities and systemic knowledge gaps. This design precisely quantifies temperature excursions and correlates them with immunogenicity outcomes, while the qualitative data elucidate root causes and vulnerabilities. Preliminary application in selected provinces has demonstrated the framework's feasibility in identifying critical breakpoints—from central storage to final administration—that jeopardise vaccine potency. The methodology's significance lies in its actionable, data-driven approach, moving beyond mere compliance monitoring to actively linking cold chain logistics with clinical outcomes. It provides a replicable model for strengthening immunisation programmes by prioritising evidence-based, targeted interventions, ultimately aiming to improve measles control and support broader public health goals across the continent.