Australian population cohort study of newly arrived refugee children: how effective is predeparture measles and rubella vaccination?

ABSTRACT

BACKGROUND: Predeparture medical screening and measles-mumps-rubella vaccination are routinely given to refugee children before departure from most transit countries en route to Australia. OBJECTIVES: The purpose of this study was to evaluate the effectiveness of this single measles-mumps-rubella vaccine and the reliability of its documentation. This is important in determining refugees' susceptibility to measles and rubella and the risk to the nonvaccinated community. METHODS: We analyzed measles and rubella serology in a comprehensively screened population of newly arrived refugees. We reviewed seropositivity rates based on age, sex, country of departure and vaccine documentation. RESULTS: Of 164 children screened, 139 (84.8%) were immune to rubella; 143 (87.7%) to measles and 119 (73.0%) to both. There was no significant difference in immunity among those of different ages or those departing different continents. Immunity rates among those with documented measles-mumps-rubella tended to be higher 91.1% for rubella, 89.1% for measles and 80.0% for both diseases, but this did not reach significance at the 5% level. There was a significant difference between males (65.9%) and females (81.3%) immune to both diseases (P = 0.042). CONCLUSIONS: This cohort demonstrated similar measles and rubella seropositivity rates to those of the Australian population, but lower rates than population seroconversion studies, which have been estimated at 95%. Males were less likely to be immune. Rates in those with documented vaccination approximated seroconversion studies. This confirms the appropriateness of current guidelines which suggest that immunization is not required in the face of documented prior vaccination, but is required without such documentation.