Evaluation of Haemophilus influenzae type b carrier status among children 10 years after the introduction of Hib vaccine in Brazil

Mem Inst Oswaldo Cruz. 2015 Sep;110(6):755-9. doi: 10.1590/0074-02760150140.

Abstract

The aim of the present study was to assess the prevalence of Haemophilus influenzae type b (Hib) nasopharyngeal (NP) colonisation among healthy children where Hib vaccination using a 3p+0 dosing schedule has been routinely administered for 10 years with sustained coverage (> 90%). NP swabs were collected from 2,558 children who had received the Hib vaccine, of whom 1,379 were 12-< 24 months (m) old and 1,179 were 48-< 60 m old. Hi strains were identified by molecular methods. Hi carriage prevalence was 45.1% (1,153/2,558) and the prevalence in the 12-< 24 m and 48-< 60 m age groups were 37.5% (517/1,379) and 53.9% (636/1,179), respectively. Hib was identified in 0.6% (16/2,558) of all children in the study, being 0.8% (11/1,379) and 0.4% (5/1,179) among the 12-< 24 m and 48-< 60 m age groups, respectively. The nonencapsulate Hi colonisation was 43% (n = 1,099) and was significantly more frequent at 48-< 60 m of age (51.6%, n = 608) compared with that at 12-< 24 m of age (35.6%, n = 491). The overall resistance rates to ampicillin and chloramphenicol were 16.5% and 3.7%, respectively; the co-resistance was detected in 2.6%. Our findings showed that the Hib carrier rate in healthy children under five years was very low after 10 years of the introduction of the Hib vaccine.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ampicillin Resistance / immunology
  • Bacterial Capsules / immunology
  • Brazil / epidemiology
  • Carrier State / immunology*
  • Carrier State / microbiology
  • Child, Preschool
  • Chloramphenicol Resistance / immunology
  • Cross-Sectional Studies
  • Haemophilus Infections / epidemiology
  • Haemophilus Infections / prevention & control*
  • Haemophilus Vaccines / therapeutic use*
  • Haemophilus influenzae type b / classification
  • Haemophilus influenzae type b / immunology*
  • Humans
  • Immunization Schedule
  • Infant
  • Mass Vaccination
  • Microbial Sensitivity Tests
  • Nasopharynx / microbiology*
  • Polymerase Chain Reaction
  • Prevalence
  • Surveys and Questionnaires

Substances

  • Haemophilus Vaccines