Effectiveness and feasibility of vaccination interventions for Indigenous and hard-to-reach populations in Latin America and the Caribbean: a systematic review and meta-analysis.

Abstract

Background: Persistent vaccination inequities affect Indigenous and hard-to-reach populations in Latin America and the Caribbean (LAC), yet evidence on effective interventions remains fragmented.

Objectives: To synthesize evidence on the effectiveness and feasibility of interventions designed to improve vaccination coverage among Indigenous and hard-to-reach populations in LAC.

Design: Systematic review and meta-analysis following PRISMA 2020 guidelines.

Methods: We searched PubMed/MEDLINE, Scopus, Web of Science, Cochrane Library, Google Scholar, and PAHO/WHO repositories for studies published between January 2015 and March 2025. Eligible studies reported primary data on vaccination coverage among Indigenous, rural, migrant, or marginalized populations in LAC. Two independent reviewers performed screening, data extraction, and quality assessment (JBI tools). Random-effects meta-analysis was conducted for comparable outcomes, with subgroup analyses by population and intervention type. Feasibility was assessed across logistical, financial, and cultural domains using an implementation science framework.

Results: Of 2750 records, 21 studies met inclusion criteria, representing 10 LAC countries. Interventions included community health worker (CHW) outreach (43%), mobile units (29%), school-based delivery (14%), digital reminders (10%), and culturally tailored campaigns (5%). Meta-analysis of 16 studies showed that individuals receiving interventions were 64% more likely to achieve complete vaccination (risk ratio (RR) = 1.64; 95% confidence interval (CI), 1.32-2.04). Effects were stronger for Indigenous populations (RR = 1.85; 95% CI, 1.42-2.25) than for other rural groups (RR = 1.45; 95% CI, 1.20-1.80). CHW outreach and mobile units showed the largest effects. Feasibility was highest for CHW and culturally adapted strategies due to community trust, low costs, and adaptability.

Conclusion: Community-based, culturally grounded interventions, particularly those integrating CHW networks and Indigenous leadership, significantly improve vaccination coverage among hard-to-reach populations in LAC. These findings support scaling equity-centered models within national immunization policies.