Bulletin of the World Health Organization

The impact of adolescent pertussis immunization, 2004–2009: lessons from Australia

Helen E Quinn & Peter B McIntyre

Volume 89, Number 9, September 2011, 666-674

Table 3. Incidence rate ratios (IRRs)a for pertussis notifications in adolescents aged 12 to 19 years for each year after diphtheria, tetanus and acellular pertussis vaccine programme roll-out, by jurisdictional group, Australia, 2004–2009

Jurisdictional groupingb Pre-programme
epidemic ratec,d (95% CI)
IRR (95% CI)
2005 2006 2007 2008 2009
Australian Capital Territory/ South Australia/Victoria 92.6 (87.4–98.0) 0.41 (0.36–0.47) 0.26 (0.23–0.31) 0.20 (0.17–0.24) 0.39 (0.34–0.35) 1.03 (0.93–1.13)
New South Wales 156.8 (150.4–163.4) 0.29 (0.25–0.32) 0.20 (0.17–0.22) 0.13 (0.11–0.15) 1.22 (1.14–1.30) 1.23 (1.15–1.31)
Western Australia 284.2 (263.2–306.9) 0.08 (0.06–0.11) 0.03 (0.02–0.05) 0.01 (0.01–0.03) 0.03 (0.02–0.05) 0.05 (0.04–0.08)
Queensland 134.7 (127.1–142.8) 0.57 (0.50–0.64) 0.36 (0.31–0.42) 0.18 (0.15–0.22) 0.29 (0.25–0.34) 0.95 (0.86–1.05

CI, confidence interval.

a These represent the ratios given by dividing the notification rate during each of the two epidemic periods after diphtheria, tetanus and acellular pertussis vaccine programme roll-out by the notification rate during the most recent epidemic period before programme roll-out.

b Jurisdictional groupings were based on programme delivery characteristics.

c The recent epidemic periods used in the analysis were as follows: Australian Capital Territory, 2003; South Australia, 2001; Victoria, 2001/2002; New South Wales, 2000/2001; Queensland, 2001/2002; Western Australia, 2004; national, 2001.6

d Per 100 000 population.