title: Reduced effectiveness of Haemophilus influenzae type b conjugate vaccine in children with a high prevalence of human immunodeficiency virus type 1 infection.
abstract: BACKGROUND
  Haemophilus influenzae type b (Hib) conjugate vaccines have successfully reduced the burden of invasive Hib disease in developed countries; however, their effectiveness in countries with a high incidence of pediatric HIV-1 is unknown.
  
  
  METHODS
  The effectiveness of Hib conjugate vaccine was prospectively evaluated in South African children. The burden of invasive Hib disease in children < 1 year old was compared in 2 cohorts. The first cohort included 22,000 African children born in 1997 [969 (4.45%) of whom were estimated to be HIV-1-infected] who were not vaccinated with Hib conjugate vaccine. This group was compared with 19,267 children [1162 (6.03%) of whom were estimated to be HIV-1 infected] vaccinated at 6, 10 and 14 weeks of age with an Hib conjugate vaccine [TETRAMUNE (polyribosylribitol phosphate-CRM(197)-diphtheria-tetanus toxoids-whole cell pertussis)] between March, 1998, and June, 1999.
  
  
  RESULTS
  The estimated burden of invasive Hib disease in nonimmunized HIV-1-infected children < 1 year of age was 5.9-fold [95% confidence interval (95% CI), 2.7 to 12.6] higher than in HIV-1-uninfected children. The overall estimated effectiveness of Hib conjugate vaccine in fully vaccinated children <1 year of age was 83.2% (95% CI 60.3 to 92.9). Vaccine effectiveness was significantly reduced in HIV-1-infected [43.9% (95% CI -76.1 to 82.1)] compared with uninfected children [96.5% (95% CI 74.4 to 99.5); P < 10(-5)]. Among three of the fully vaccinated HIV-1-infected children who developed invasive Hib disease, the anti-Hib polyribosylribitol phosphate serum antibody concentrations were 0.23, 0.25 and 0.68 microg/ml.
  
  
  CONCLUSIONS
  Although the Hib conjugate vaccine was less effective among HIV-1-infected than among uninfected children, it was 83% effective in preventing overall invasive Hib disease and therefore should be considered for inclusion in the routine vaccination schedule by other African countries.
authors.affiliation: NHLS/Wits/MRC Pneumococcal Diseases Research Unit, University of Witwatersrand, Johannesburg, South Africa.
authors.forename: Shabir A
authors.initials: SA
authors.lastname: Madhi
authors.forename: Karen
authors.initials: K
authors.lastname: Petersen
authors.forename: Manikant
authors.initials: M
authors.lastname: Khoosal
authors.forename: Robin E
authors.initials: RE
authors.lastname: Huebner
authors.forename: Nontombi
authors.initials: N
authors.lastname: Mbelle
authors.forename: Rosalia
authors.initials: R
authors.lastname: Mothupi
authors.forename: Haroon
authors.initials: H
authors.lastname: Saloojee
authors.forename: Heather
authors.initials: H
authors.lastname: Crewe-Brown
authors.forename: Keith P
authors.initials: KP
authors.lastname: Klugman
mesh_terms: D000917:Antibody Formation; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000150:complications* / Q000276:immunology; D015497:HIV-1 / Q000472:pathogenicity*; D006192:Haemophilus Infections / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology; D018073:Haemophilus Vaccines / Q000276:immunology* / Q000494:pharmacology; D019741:Haemophilus influenzae type b / Q000276:immunology / Q000472:pathogenicity*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015995:Prevalence; D011446:Prospective Studies; D013019:South Africa
chemical_list: D018073:Haemophilus Vaccines