Vaccination coverage among migrants: A systematic review and meta-analysis

Abstract

Background: Migrants, a population vulnerable to communicable diseases, face multiple barriers in access to immunization programs. Individual studies suggest that they suffer immunization inequity compared to non-migrants, but the gap in vaccination has not been quantified. This systematic review assessed quantitatively the level of vaccination coverage among migrants, in comparison with non-migrants, collating the published literature.

Methods: Review protocol was prospectively registered (PROSPERO CRD42021228061). A literature search without language restrictions was conducted in PubMed, Scopus and Web of Science, from database inception to February 2021. This review included observational studies that provided the vaccination rates among migrant and non-migrant groups. Study quality was assessed using Newcastle-Ottawa scale. Data were synthesized pooling data from individual studies to generate summary odds ratio (OR) with 95% confidence interval (CI) using random effects model, assessing heterogeneity with I² statistic and publication bias with funnel asymmetry analysis.

Findings: There were 44 relevant studies (7,937,996 participants). Overall risk of bias was low in 13 (30%), moderate in 22 (50%) and high in 9 (20%) studies. Point estimates of individual ORs showed lower vaccination coverage among migrants in 36 of 39 meta-analyzable studies. Overall, the odds of vaccination coverage among migrants were lower compared to non-migrants (7,375,184 participants; summary OR 0.50; 95% CI 0.37-0.66; I² 99.9%). There was no funnel asymmetry.

Interpretation: Migrants are half as often vaccinated compared to non-migrants. Public health prevention programs need to prioritize vaccination equity, not just to protect migrants but also to protect the host communities.

Keywords: Cobertura de vacunación; Migrant; Migrantes; No migrantes; Non-migrant; Vaccination coverage.