title: Long-term trends in invasive Haemophilus influenzae type B disease among indigenous Australian children following use of PRP-OMP and PRP-T vaccines.
abstract: BACKGROUND
  Among indigenous populations with high incidence and early onset of invasive Haemophilus influenzae type b (Hib) disease, PRP-OMP vaccines are used in the United States and PRP-T vaccines in Canada. In Australia, PRP-OMP vaccines were exclusively used in indigenous children from 1993 until they were replaced by PRP-T between late 2005 and 2009.
  
  
  METHODS
  Analytic descriptive study of 20 years of enhanced surveillance data (1993-2013) for invasive Hib disease in Australian children <10 years of age was conducted.
  
  
  RESULTS
  Of 579 Hib cases under 10 years of age reported from vaccine introduction in 1993 to 2013, 78 (13%) were in indigenous children, 47 (60%) of whom lived in regions with high prevaccine incidence. In this population, incidence per 100,000 declined from 18.1 (95% confidence interval [CI]: 10.4, 29.4) in the early PRP-OMP period (1993-1996) to 6.2 (95% CI: 4.0, 9.2) and 4.7 (95% CI: 1.7, 10.3) in the later PRP-OMP (1996-2009) and PRP-T periods (2009-2013), respectively. The indigenous:nonindigenous incidence rate ratio increased to 43 (95% CI: 16, 145) and 58 (95% CI: 7, 2660) in the later PRP-OMP and PRP-T periods, respectively, more than 10-fold higher than in lesser-incidence Australian regions.
  
  
  CONCLUSIONS
  We found no change in Hib incidence among indigenous Australian children living in high-incidence regions in the first 4 years following a change to PRP-T-containing combination vaccines. This may be of relevance to North American indigenous populations characterized by suboptimal living conditions and young age of onset for whom PRP-OMP continues to be recommended, such as Alaska Natives.
authors.affiliation: *National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, Children's Hospital at Westmead, Sydney, Australia; and †University of Sydney, Sydney, Australia.
authors.forename: Robert Ian
authors.initials: RI
authors.lastname: Menzies
authors.forename: Kyla Margaret
authors.initials: KM
authors.lastname: Bremner
authors.forename: Han
authors.initials: H
authors.lastname: Wang
authors.forename: Frank Hudson
authors.initials: FH
authors.lastname: Beard
authors.forename: Peter Bruce
authors.initials: PB
authors.lastname: McIntyre
mesh_terms: D001315:Australia / Q000453:epidemiology; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control*; D001425:Bacterial Outer Membrane Proteins / Q000008:administration & dosage / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D006192:Haemophilus Infections / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control*; D018073:Haemophilus Vaccines / Q000008:administration & dosage / Q000276:immunology*; D019741:Haemophilus influenzae type b / Q000302:isolation & purification*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D011135:Polysaccharides, Bacterial / Q000008:administration & dosage / Q000276:immunology*; D044382:Population Groups; D013745:Tetanus Toxoid / Q000008:administration & dosage / Q000276:immunology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D018073:Haemophilus Vaccines; C055753:Haemophilus influenza type b polysaccharide vaccine-tetanus toxin conjugate; C061964:Haemophilus influenzae-type b polysaccharide-Neisseria meningitidis outer membrane protein conjugate vaccine; D011135:Polysaccharides, Bacterial; D013745:Tetanus Toxoid