title: Estimates of the effectiveness of a whole-cell pertussis vaccine from an outbreak in an immunized population.
abstract: Pertussis has re-emerged as a public health problem in Canada in recent years, emphasizing concerns about the effectiveness of the currently licensed whole-cell vaccine. Following a 1994 outbreak in Nova Scotia, we conducted a case-control study of 483 children aged < 10 years to assess vaccine effectiveness. Ninety-three percent of children aged 6 months and above had received three or more doses of vaccine, however, only 78% had received age-appropriate immunization. Among children aged 4 years and more, vaccine effectiveness against laboratory-confirmed pertussis was 57% (95% CI, 23-77%) for age-appropriate immunization (five doses) vs partial or no immunization. Vaccine effectiveness increased with increasing number of doses from 25% (95% CI, -58-65%) for three or more doses to 55% (95% CI, -15-83%) for five doses, compared with 0-2 doses.
authors.affiliation: Field Epidemiology Training Program, Laboratory Centre for Disease Control (LCDC), Ottawa, Canada.
authors.forename: A D
authors.initials: AD
authors.lastname: Bentsi-Enchill
authors.forename: S A
authors.initials: SA
authors.lastname: Halperin
authors.forename: J
authors.initials: J
authors.lastname: Scott
authors.forename: K
authors.initials: K
authors.lastname: MacIsaac
authors.forename: P
authors.initials: P
authors.lastname: Duclos
mesh_terms: D000367:Age Factors; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000517:prevention & control*; D005260:Female; D006801:Humans; D017589:Immunization Programs / Q000706:statistics & numerical data; D007223:Infant; D008297:Male; D009674:Nova Scotia / Q000453:epidemiology; D010567:Pertussis Vaccine / Q000276:immunology*; D014917:Whooping Cough / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control*
chemical_list: D010567:Pertussis Vaccine