Acellular pertussis vaccine effectiveness for children during the 2009-2010 pertussis epidemic in Queensland

Sarah L Sheridan1, Bradley J McCall2, Craig A Davis3

  • 1Queensland Children's Medical Research Institute, University of Queensland, Brisbane, QLD, Australia. s.sheridan@uq.edu.au.

Insights

Acellular pertussis vaccine offers good protection in young children, but its effectiveness wanes with age. Increased testing identified milder pertussis cases, potentially lowering vaccine effectiveness estimates.

Area of Science:

  • Immunization
  • Pediatric Infectious Diseases
  • Public Health

Background:

  • Pertussis (whooping cough) remains a concern in young children.
  • Acellular pertussis vaccines are widely used but their long-term effectiveness requires ongoing evaluation.

Purpose of the Study:

  • To assess the effectiveness of acellular pertussis vaccine doses against pertussis notification and hospitalization in children.
  • To evaluate vaccine effectiveness (VE) across different age groups (1-4 years and 5-12 years) and vaccination schedules.

Main Methods:

  • A population-based retrospective study in Queensland, Australia (2009-2010).
  • Utilized routinely collected data on pertussis notifications, hospitalizations, testing (including PCR), and vaccinations.
  • Employed the screening method to calculate vaccine effectiveness.

Main Results:

  • Vaccine effectiveness against pertussis notification and hospitalization in 1-4 year olds was high (83.5%-89.4%).
  • Effectiveness against notification in 5-12 year olds varied significantly by year (71.2%-87.7% in 2009, 34.7%-70.3% in 2010).
  • Increased use of PCR testing coincided with higher notification rates and potentially milder disease detection.

Conclusions:

  • Acellular pertussis vaccine provides robust protection in the initial years post-vaccination.
  • Vaccine effectiveness appears to decrease as children age.
  • Changes in diagnostic practices, particularly increased PCR testing, may influence pertussis notification rates and VE estimates.
Abstract

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