MMR vaccine coverage and associated factors among overseas-born refugee children resettled in Aotearoa New Zealand: a national retrospective cohort study.

Background: Refugee children may be under-immunised against common vaccine-preventable diseases due to a myriad of factors related to their migration journey. Methods: This retrospective cohort study explored the rates and determinants of enrolment on the National Immunisation Register (NIR) and measles, mumps and rubella (MMR) coverage among refugee children up to 18 years old who resettled in Aotearoa New Zealand (NZ) from 2006 to 2013. Univariate and multivariable logistic regression were conducted to determine associations. Findings: Of the cohort (N = 2796), two thirds of the children (69%) were enrolled on the NIR. Among this sub-cohort (n = 1926), less than one third (30%) were age-appropriately vaccinated with MMR. MMR coverage was highest among younger children and improved over time. Logistic modelling revealed that visa category, year of arrival, and age group were significant factors that influenced NIR enrolment and MMR vaccine uptake. Those arriving via asylum seeking, family reunification and humanitarian pathways were less likely to be enrolled and vaccinated compared to refugees who entered under the national quota programme. More recent arrivals and younger children were more likely to be enrolled and vaccinated compared to children who arrived in NZ longer ago and were older. Interpretation: Resettled refugee children have suboptimal NIR enrolment and MMR coverage rates which varied significantly by visa category, highlighting the need for immunisation services to better engage with all refugee families. These findings suggest that broad structural factors related to policy and immunisation service delivery may influence the differentials seen. Funding: Health Research Council of New Zealand (18/586).