Efficacy in infancy of oligosaccharide conjugate Haemophilus influenzae type b (HbOC) vaccine in a United States population of 61,080 children. The Northern California Kaiser Permanente Vaccine Study Center Pediatrics Group

Pediatr Infect Dis J. 1991 Feb;10(2):97-104. doi: 10.1097/00006454-199102000-00004.


The efficacy of the HbOC conjugate Haemophilus influenzae type b vaccine was evaluated in a study population of 61,080 infants in the Northern California Kaiser Permanente Medical Care Program. Between February, 1988, and June, 1990, the HbOC vaccine was given as part of a three-dose series at 2, 4, and 6 months of age to 20,800 infants. The study population included children with a well-care visit at a study center during the first 6 months of life. There were 25 cases of Haemophilus influenzae type b disease in the study population: 22 in unvaccinated children and 3 in children who received only one dose of HbOC vaccine. The efficacy of the full three-dose series was evaluated by several methods: a primary analysis comparing fully vaccinated children with unvaccinated children from 7 to 18 months of age; a stratified exact analysis adjusted for age and seasonality; and a case-control analysis which further adjusted for known risk factors. The efficacy of three doses of vaccine was 100% with the lower bound of the 95% confidence interval for the three analyses at 68, 71, and 64%, respectively. There were no cases of disease resulting from two doses of HbOC vaccine yielding an estimate of 100% efficacy (95% confidence interval, 47 to 100) for two doses of HbOC vaccine. However, for children who had received only one dose of HbOC vaccine, vaccine efficacy was estimated to be 26% and the possibility that one dose of HbOC vaccine had no efficacy could not be excluded.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Clinical Trial
  • Comparative Study
  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins*
  • Bacterial Vaccines*
  • Bias
  • California
  • Case-Control Studies
  • Cohort Studies
  • Confidence Intervals
  • Haemophilus Infections / prevention & control*
  • Haemophilus Vaccines*
  • Haemophilus influenzae / immunology*
  • Humans
  • Immunization Schedule
  • Infant
  • Research Design
  • Vaccination
  • Vaccines, Synthetic


  • Bacterial Proteins
  • Bacterial Vaccines
  • Haemophilus Vaccines
  • Vaccines, Synthetic
  • HibTITER protein, Haemophilus influenzae