Haemophilus influenzae type b experience in Alaska is reported

Researchers report the Alaska Haemophilus influenzae type b experience in a recent issue of the journal Pediatrics.

  Researchers from the U.S. Centers for Disease Control and Prevention report, “Before 1991, Alaska Native children experienced one of the highest rates of invasive Haemophilus influenzae type b disease. H. influenzae type b vaccine has led to a near-elimination of invasive H. influenzae type b disease in the United States. We describe challenges encountered in controlling H. influenzae type b disease in Alaska and update the current status of H. influenzae disease and carriage in Alaska as lessons to other populations.”

“We reviewed data from statewide H. influenzae disease surveillance conducted during 1980-2004,” said Rosalyn Singleton and colleagues. “Vaccine coverage data were based on audits from tribal facilities and the National Immunization Survey. H. influenzae type b colonization data were based on six carriage studies.”

  The investigators reported, “After universal infant vaccination in 1991, H. influenzae type b disease among Alaska Native and non-Native children <5 years of age decreased by 94% and 96%, respectively. After a 1996 change in H. influenzae type b vaccine from polyribosylribitol phosphate-outer membrane protein conjugate vaccine to H. influenzae type b oligosaccharide-CRM197 vaccine, the incidence of H. influenzae type b disease increased in rural Alaska Natives from 19.8 to 91.1 cases per 100,000 per year <5 years of age.

  “During 2001-2004, with use of polyribosylribitol phosphate outer membrane protein conjugate vaccine, the rate of H. influenzae type b disease in Alaska Native and non-Native children aged <5 years decreased to 5.4 and 0 per 100,000 per year, respectively,” the investigators stated.

  “In post-vaccine studies, H. influenzae type b carriage has decreased in Alaska Native children <5 years of age,” concluded Singleton and associates. “H. influenzae type b vaccination has resulted in a dramatic decrease in invasive H. influenzae type b disease in Alaska; however, despite high rates of H. influenzae type b vaccine coverage, H. influenzae type b disease rates among rural Alaska Native children <5 years of age remain higher than the rates among non-Native Alaska and other U.S. children.

  “Equity in disease rates may not be achieved in indigenous populations with the current vaccines unless other environmental and household factors contributing to disease transmission are addressed,” they advised.

  Singleton and coauthors published their study in Pediatrics (The Alaska Haemophilus influenzae type b experience: Lessons in controlling a vaccine-preventable disease. Pediatrics, 2006;118(2):E421-E429).