Differing serologic responses to an Haemophilus influenzae type b polysaccharide-Neisseria meningitidis outer membrane protein conjugate (PRP-OMPC) vaccine in Australian Aboriginal and Caucasian infants - implications for disease epidemiology

This study compared Hib antibody responses to a single lot of PRP-OMPC vacc ine given at 7, 4 and 12 months to 57 Aboriginal infants in rural areas of the Northern Territory and 56 Caucasian infants in Sydney, Australia. The A boriginal infants had lower levels of antibody in cord blood (P > 0.05), wh ich were significantly lower (P < 0.02) by 2 months of age. Antibody respon ses to one or two doses of vaccine, measured at 4 and 12 months of age, wer e similar but the geometric mean titre following the booster dose in Aborig inal infants was significantly lower (1.98 vs 6.04 mcg/ml, P = 0.002). Low preimmunisation antibody is consistent with the early onset of Hib disease in Aboriginal infants before immunisation. Lower responses to boosting coul d correlate with persistence of Hib colonisation in indigenous populations. (C) 2000 Elsevier Science Ltd. All rights reserved.