Table 1 Epidemiological characteristics of ICU admissions due to influenza A in 2010 and 2009 in Australia and New Zealand
| Â | 2010 | 2009 | P- value |
|---|---|---|---|
Number of Influenza A cases | 315 | 1113 | Â |
   H1N1 2009 | 283 (90%) | 921 (83%) | 0.002 |
   Seasonal H1N1 | 0 (0%) | 36 (3%) | < 0.001 |
   Seasonal H3N2 | 3 (1%) | 24 (2%) | 0.17 |
   Not sub-typed or other | 29 (9%) | 132 (12%) | 0.22 |
Incidence of admission to ICU per million inhabitants, (95% CI) | Â | Â | Â |
   ANZ | 10.6 (9.4 to 11.9) | 35.2 (32.9 to 37.5) | < 0.001 |
   Australia | 9 (7.8 to 10.3) | 36.5 (34 to 39.1) | < 0.001 |
   New Zealand | 18.8 (14.6 to 23) | 28.3 (23.2 to 33.5) | 0.005 |
Maximum daily ICU occupancy per million inhabitants, (95% CI) | 2.4 (1.8 to 3.0) | 7.5 (6.5 to 8.6) | < 0.001 |