Clinical Epidemiology and Predictors of Outcome in Children Hospitalised With Influenza A(H1N1)pdm09 in 2009

*Hospital admission rate = number of children aged <15 years admitted for laboratory-confirmed influenza compared to total number of children aged <15 years admitted to hospital for the period 1 June 2009–30 September 2009.
**One or more conditions.

ARDS, Acute respiratory distress syndrome; LOS, length of hospital stay; SD, standard deviation; POC, Point of care tests (rapid antigen test). Bold values indicates significant difference between groups.

PICU, paediatric intensive care unit.
*Age ≥ 4 years (reference variable).
**Laboratory-proven bacterial co-infection at a sterile site within 72 hours of admission.
***Vaccination for seasonal influenza.
^†SEIFA (disadvantaged).

Authors and Disclosures

Gulam Khandaker^a,b,c, Yvonne Zurynski^a,d, Greta Ridley^a,d, Jim Buttery^e, Helen Marshall^f, Peter C. Richmond^g, Jenny Royle^h, Michael Goldⁱ, Tony Walls^j,k, Bruce Whitehead^l, Peter McIntyre^b,c,j, Nicholas Wood^b,j, Robert Booy^b,c,j and Elizabeth J. Elliott^a,c,d,j

^aThe Discipline of Paediatrics and Child Health, The University of Sydney, Sydney, NSW, Australia. ^bNational Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, The Children's Hospital at Westmead, Sydney, NSW, Australia. ^cThe Marie Bashir Institute for Infectious Diseases and Biosecurity (MBI), Sydney Medical School, the University of Sydney, Sydney, NSW, Australia. ^dThe Australian Paediatric Surveillance Unit, Sydney, NSW, Australia. ^eDepartment of Paediatrics, Murdoch Children's Research Institute, Monash Children's Hospital, Monash University, Melbourne, Vic., Australia. ^fVaccinology and Immunology Research Trials Unit, Women's and Children's Hospital, Robinson Institute and School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, SA, Australia. ^gSchool of Paediatrics and Child Health, University of Western Australia, Princess Margaret Hospital for Children, Perth, WA, Australia. ^hImmunisation Service, Department of General Medicine, Royal Children's Hospital, Melbourne, Vic., Australia. ⁱSchool of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, SA, Australia. ^jThe Sydney Children's Hospitals Network (SCHN), Sydney, NSW, Australia. ^kDepartment of Paediatrics, University of Otago, Christchurch, New Zealand. ^lDepartment of Paediatric Respiratory and Sleep Medicine, John Hunter Children's Hospital, Newcastle, NSW, Australia.

Correspondence
Prof Elizabeth J Elliott, The Australian Paediatric Surveillance Unit, c/o The Children's Hospital at Westmead, Locked Bag 4001 Westmead, NSW 2145, Australia. E-mail: elizabeth.elliott@health.nsw.gov.au

Conflict of interests
GK was an investigator in studies supported by Roche. HM has participated as a Board Member of Global Advisory Boards for Merck, Novartis and GlaxoSmithKline, has received travel support to present scientific data at international meetings and is an investigator in industry-sponsored clinical vaccine trials. Her institution has received funding for investigator-led research from Novartis, Pfizer and GlaxoSmithKline. JB has served on advisory and/or data safety monitoring committees for CSL Vaccines and GSK for which the Murdoch Children's Research Institute (MCRI) receives payments into an educational fund. MCRI has received travel support for JB to present scientific data at international meetings, and he is an investigator in industry-sponsored vaccine trials. PCR is a member of the Vaccine Trials Group. The Vaccine Trials Group has received institutional funding for research from vaccine providers including CSL Biotherapies, Sanofi Pasteur, Baxter and GlaxoSmithKline. PCR has also previously been a member of a CSL Limited vaccine scientific advisory board and received travel support from Baxter, Sanofi and Pfizer to present scientific data at international meetings. RB has received financial support from CSL, Sanofi, GSK, Roche, Novartis and Wyeth, to conduct research and present at scientific meetings. Any funding received is directed to an NCIRS research account at The Children's Hospital at Westmead and is not personally accepted by Professor Booy. The other authors declare that they have no conflict of interests in relation to this work.

Author contributions
Gulam Khandaker (gulam.khandaker@health.nsw.gov.au): involved in data analysis and interpretation and contributed to the first and subsequent drafts of the manuscript. Yvonne Zurynski (yvonne.zurynski@health.nsw.gov.au): contributed to development of the initial concept, protocols and data collection forms; data analysis and critical review of the first and subsequent version of the manuscript. Greta Ridley (greta.ridley@health.nsw.gov.au): involved in data analysis and interpretation and contributed to the first and subsequent drafts of the manuscript. Jim Buttery (jim.buttery@mcri.edu.au): contributed to collection of surveillance data, data cleaning, study analysis and drafting the manuscript and approved the final version to be submitted. Helen Marshall (helen.marshall@adelaide.edu.au): contributed to collection of surveillance data, data cleaning, study analysis and drafting the manuscript and approved the final version to be submitted. Peter C Richmond (prichmond@meddent.uwa.edu.au): contributed to collection of surveillance data, data cleaning, study analysis and drafting the manuscript and approved the final version to be submitted. Jenny Royle (jenny.royle@bigpond.com): contributed to collection of surveillance data, data cleaning, study analysis and drafting the manuscript and approved the final version to be submitted. Michael Gold (michael.gold@adelaide.edu.au): contributed to collection of surveillance data, data cleaning, study analysis and drafting the manuscript and approved the final version to be submitted. Tony Walls (tony.walls@otago.ac.nz): contributed to collection of surveillance data, data cleaning, study analysis and drafting the manuscript and approved the final version to be submitted. Bruce Whitehead (Bruce.Whitehead@hnehealth.nsw.gov.au): contributed to collection of surveillance data, data cleaning, study analysis and drafting the manuscript and approved the final version to be submitted. Peter McIntyre (peter.mcintyre@health.nsw.gov.au): contributed to collection of surveillance data, data cleaning, study analysis and drafting the manuscript and approved the final version to be submitted. Nicholas Wood (nicholas.wood@gov.au): contributed to collection of surveillance data, data cleaning, study analysis and drafting the manuscript and approved the final version to be submitted. Robert Booy (robert.booy@health.nsw.gov.au): liaised with additional hospitals in NSW to obtain their involvement in the study. Contributed to development of the initial study concept, protocols and data collection forms; data analysis and critical review of the first and subsequent version of the manuscript. Elizabeth J Elliott, (elizabeth.elliott@health.nsw.gov.au): liaised with additional hospitals in NSW to obtain their involvement in the study. Contributed to development of the initial study concept, protocols and data collection forms; data analysis and critical review of the first and subsequent version of the manuscript.