Table 1.
Summary of key seasonal signatures of monthly pertussis notifications from January 1991 to December 2016 for all of Australia and for each subgroup (by states and territories and by age groups)
| Multiannual cycle length in years | Peak month | Yearly amplitude | Multiannual amplitude | |
|---|---|---|---|---|
| Australia | 3.8 years | Early November (10.80–11.78) | 1.15 (1.11–1.19) | 1.04 (1.01–1.09) |
| States/Territories | ||||
| New South Wales | 3.8 years | Early November (10.45–11.74) | 1.15 (1.10–1.20) | 1.05 (1.00–1.10) |
| Victoria and Tasmania | 3.0 years | Mid-December (11.57–1.22) | 1.13 (1.07–1.19) | 1.08 (1.02–1.13) |
| Queensland and Northern Territory | 3.8 years | Early December (11.40–12.87) | 1.13 (1.08–1.18) | 1.06 (1.01–1.12) |
| South Australia | 4.4 years | Early October (9.58–10.92) | 1.18 (1.11–1.24) | 1.06 (1.00–1.12) |
| Western Australia | 3.8 years | Mid-November (10.84–12.43) | 1.17 (1.10–1.25) | 1.06 (0.99–1.13) |
| Age groups | ||||
| <6 months | 3.8 years | Mid-January (12.65–2.07) | 1.20 (1.12–1.27) | 1.15 (1.07–1.23) |
| 6 months – 4 years | 3.8 years | Early January (12.49–1.92) | 1.16 (1.10–1.22) | 1.06 (1.00–1.11) |
| 5 years – 9 years | 3.8 years | Mid-November (10.85–11.90) | 1.22 (1.16–1.28) | 1.05 (1.00–1.10) |
| 10 years – 64 years | 3.8 years | Late October (10.46–11.41) | 1.15 (1.11–1.19) | 1.04 (1.01–1.08) |
| ⩾65 years | 5.3 years | Late November (11.00–12.58) | 1.15 (1.09–1.21) | 1.13 (1.05–1.21) |
Numbers inside ( ) are the estimated 95% CIs. Numbers corresponding to the peak month are interpreted as the month and its part in a 12-month calendar. Amplitude is interpreted as the % increase observed in notifications during the peaks as compared to the seasonal average.