title: Haemophilus influenzae type b vaccination: long-term protection.
abstract: OBJECTIVE
  To identify evidence of the impact of Haemophilus influenzae type b (Hib) conjugate vaccine on the epidemiology of invasive Hib disease.
  
  
  METHODS
  This review was based on a search of MEDLINE, LILACS, technical reports, national and international guidelines (publications from 1991 to 2005). The keywords Haemophilus influenzae type b, immunization, impact, and effectiveness, alone or in combination, were used to retrieve the articles. Studies published before 1991 and cited in the references of the studies reviewed were analyzed for useful information.
  
  
  RESULTS
  Introduction of the Hib conjugate vaccine produced great decline in the incidence of invasive Hib disease in childhood in countries where this vaccine was introduced into the routine immunization schedule. Nevertheless, the resurgence of invasive Hib disease in some regions has challenged several researchers to identify the reasons for this epidemiological pattern, as well as the measures to be implemented in order to avoid such a phenomenon.
  
  
  CONCLUSIONS
  The use of Hib conjugate vaccine on a population scale has been greatly effective; nonetheless, changes in the vaccination scheme seem to be necessary to keep invasive Hib disease under control.
authors.affiliation: Departamento de Pediatria, Faculdade de Medicina da Bahia, Universidade Federal da Bahia (UFBA), Salvador, BA, Brazil. nascimentocarvalho@hotmail.com
authors.forename: Cristiana M
authors.initials: CM
authors.lastname: Nascimento-Carvalho
authors.forename: Ana Lúcia S Sgambatti
authors.initials: AL
authors.lastname: de Andrade
mesh_terms: D016667:Bacterial Capsules; D014943:Global Health; D006192:Haemophilus Infections / Q000150:complications / Q000276:immunology / Q000517:prevention & control*; D018073:Haemophilus Vaccines / Q000276:immunology / Q000627:therapeutic use*; D019741:Haemophilus influenzae type b / Q000276:immunology*; D006801:Humans; D017589:Immunization Programs / Q000706:statistics & numerical data; D007115:Immunization Schedule; D008583:Meningitis, Haemophilus / Q000382:microbiology; D011135:Polysaccharides, Bacterial / Q000276:immunology / Q000627:therapeutic use*; D013997:Time Factors; D014611:Vaccination / Q000592:standards / Q000706:statistics & numerical data; D017778:Vaccines, Combined; D018074:Vaccines, Conjugate
chemical_list: D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D011135:Polysaccharides, Bacterial; D017778:Vaccines, Combined; D018074:Vaccines, Conjugate