Vaccine-preventable diseases and immunisation coverage among migrants and non-migrants worldwide: A scoping review of published literature, 2006 to 2016.

BACKGROUND: Studies of vaccine-preventable disease (VPD) burden and immunisation coverage among migrants compared to locally-born populations present a mixed picture on whether migrants experience disproportionate VPD rates and immunisation inequities, and what the associated factors are. We conducted a scoping review to explore differences in VPD burden and immunisation coverage between migrants and non-migrants worldwide. METHODS: We followed Arksey and O'Malley's five stage scoping review method. We searched for empirical, peer-reviewed literature published in English that compared VPD burden and/or immunisation coverage between migrant and non-migrant groups published between 2006 and 2016 using MEDLINE, EMBASE, CINAHL, Sociological Abstracts, and Web of Science databases. Relevant information from the studies were charted in Microsoft Excel and results were summarised using a descriptive analytical method. RESULTS: Forty-five studies met the inclusion criteria (n = 13 reporting on VPD burden; n = 27 reporting on immunisation rates; n = 5 reporting on both). Studies that met the criteria only reported findings from high income countries or high-middle income countries. Accounting for results that were presented according to separate ethnic migrant sub-groups, almost all of the studies comparing VPD burden (n = 17, 89%) reported higher burden among migrants compared to non-migrants, while most studies measuring immunisation rates (n = 26, 70%) noted lower rates among migrants. Numerous factors contributed to these findings, including the influence of migrants' nativity, socio-economic status, migration background, generation status, residential duration, cultural/personal beliefs, language proficiency and healthcare utilisation. CONCLUSIONS: Considerable variability of study foci and methodologies limited our ability to make definitive conclusions and comparisons, but the literature suggests that migrant populations generally experience higher VPD burden and lower immunisation rates. The findings highlight a number of important considerations for future research and immunisation programme planning. Future research should explore factors that influence VPD burden and immunisation rates, and strategies to overcome barriers to vaccine uptake among migrants.