IMMUNITY TO HEPATITIS-B, POLIOMYELITIS AND MEASLES IN FULLY VACCINATED ABORIGINAL AND TORRES STRAIT ISLAND CHILDREN

Objective: To determine the immunity to hepatitis B, poliomyelitis and measles in fully vaccinated Aboriginal and Torres Strait Island child ren in north Queensland. Methodology: A cross-sectional survey of immu nity in a sample of children; 101 fully vaccinated Aboriginal and Torr es Strait Island children, with a median age of 24.5 months, from 10 c ommunities in North Queensland participated in this study. The main ou tcome measures were the prevalence of adequate antibody levels against hepatitis B, poliomyelitis and measles. Results: Only 54% (95% CI 44- 63%) of the children had adequate immunity (greater than or equal to 1 0 m iu/mL) to hepatitis B, and one child had been infected despite vac cination. Although all the children (95% CI 96-100%) had adequate immu nity (i.e, neutralizing antibodies at a dilution of greater than or eq ual to 1:8) to poliovirus 2, only 93% (95% CI 86-96%) and 60% (95% CI 50-69%) had adequate immunity to polioviruses 1 and 3, respectively. N early all (96%; 95% CI 90-98%) of the children had adequate immunity ( i.e. detectable IgG antibody) to measles. Conclusions: Although a rela tively low proportion of the children had adequate antibody levels aga inst hepatitis B the clinical significance of this observation is unce rtain. Further studies are needed to determine whether fully vaccinate d Torres Strait Island children have been adequately protected and whe ther they require a booster dose of hepatitis B vaccine. A substantial proportion of fully vaccinated Aboriginal and Torres Strait Island ch ildren are inadequately protected against poliomyelitis, and therefore any such child with acute flaccid paralysis should be investigated fu lly for poliomyelitis. Vaccinated Aboriginal and Torres Strait Island children are well protected against measles, as are other Australian c hildren.