To describe in detail the pediatric intensive care experience of influenza A, particularly pandemic H1N1-09, in Australia and New Zealand during the 2009 Southern Hemisphere winter and to compare the pediatric experience with that of adults.


This was an inception-cohort study of all children who were admitted to intensive care with confirmed influenza A during winter 2009 at all general ICUs and PICUs in Australia and New Zealand.


From June 1 through August 31, 2009, 107 children (20.0 per million [95% confidence interval: 16.1–23.8]) with influenza A, including 83 (15.5 per million [95% confidence interval: 12.1–18.9]) with H1N1-09 were admitted to ICUs. Fifty-two percent (39 of 75) of children with H1N1-09 had 1 or more comorbidity, most commonly neurologic (20%). Most (48 of 83 [58%]) presented with pneumonia. Thirteen of 83 (16%) had neurologic presentations. Eighty percent of the children with H1N1-09 required ventilation. Mortality was lower than in adults: 6 of 83 (7%) vs 114 of 668 (17%) (P = .02). The median length of stay for children with H1N1-09 was 5 days. Children with H1N1-09 occupied 773 bed-days (147 per million children) and 5.8% of specialist PICU beds. Presentation with septic shock or after cardiac arrest and the presence of 1 or more comorbidities were risk factors for severe disease.


H1N1-09 caused a substantial burden on pediatric intensive care services in Australia and New Zealand. Compared with adults, children more commonly had nonrespiratory presentations and required ventilation more often but had a lower mortality rate.

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