Christopher C Blyth1,2,3,4, Kristine K Macartney5,6,7, Jocelynne McRae5,7, Julia E Clark8, Helen S Marshall9, Jim Buttery10,11, Joshua R Francis12, Tom Kotsimbos13, Paul M Kelly14, Allen C Cheng15,16. 1. School of Medicine, University of Western Australia, Perth. 2. Department of Infectious Disease, Perth Children's Hospital, Perth. 3. PathWest Laboratory Medicine, QEII Medical Centre, Perth. 4. Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth. 5. National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, University of Sydney, New South Wales. 6. Department of Infectious Diseases and Microbiology, Children's Hospital Westmead, New South Wales. 7. School of Paediatrics and Child Health, University of Sydney, New South Wales. 8. Infection Management and Prevention Service, Lady Cilento Children's Hospital, Brisbane, Queensland. 9. Women's and Children's Health Network, Robinson Research Institute and Adelaide Medical School, The University of Adelaide, South Australia. 10. Department of Infection and Immunity, Monash Children's Hospital, Monash Health, Melbourne, Victoria. 11. Monash Centre of Health Care Research and Implementation, Departments of Paediatrics, Monash University, Melbourne, Victoria. 12. Royal Darwin Hospital and Menzies School of Health, Northern Territory, Melbourne, Victoria. 13. Department of Allergy, Immunology and Respiratory Medicine, Alfred Health, Monash University, Melbourne, Victoria. 14. ACT Government Health Directorate, Australian National University Medical School, Canberra, Australian Capital Territory, Melbourne, Victoria. 15. Infection Prevention and Healthcare Epidemiology Unit, Alfred Health, Melbourne, Victoria. 16. School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria.
Abstract
BACKGROUND: In 2017, Australia experienced record influenza notifications. Two surveillance programs combined to summarize the epidemiology of hospitalized influenza in children and report on vaccine effectiveness (VE) in the context of a limited nationally funded vaccination program. METHODS: Subjects were prospectively recruited (April-October 2017). Case patients were children aged ≤16 years admitted to 11 hospitals with an acute respiratory illness and laboratory-confirmed influenza. Controls were hospitalized with acute respiratory illness and tested negative for influenza. VE estimates were calculated using the test-negative design. RESULTS: A total of 1268 children were hospitalized with influenza: 31.5% were <2 years old, 8.3% were indigenous, and 45.1% had comorbid conditions predisposing to severe influenza. Influenza B was detected in 34.1% with influenza A/H1N1 and A/H3N2 detected in 47.2% and 52.8% of subtyped influenza A specimens. The median length of stay was 3 days (interquartile range, 1-5), 14.5% were admitted to the intensive care unit, and 15.9% received oseltamivir. Four in-hospital deaths occurred (0.3%): one was considered influenza associated. Only 17.1% of test-negative-controls were vaccinated. The VE of inactivated quadrivalent influenza vaccine for preventing hospitalized influenza was estimated at 30.3% (95% confidence interval, 2.6%-50.2%). CONCLUSIONS: Significant influenza-associated morbidity was observed in 2017 in Australia. Most hospitalized children had no comorbid conditions. Vaccine coverage and antiviral use was inadequate. Influenza vaccine was protective in 2017, yet VE was lower than previous seasons. Multiple Australian states have introduced funded preschool vaccination programs in 2018. Additional efforts to promote vaccination and monitor effectiveness are required.
BACKGROUND: In 2017, Australia experienced record influenza notifications. Two surveillance programs combined to summarize the epidemiology of hospitalized influenza in children and report on vaccine effectiveness (VE) in the context of a limited nationally funded vaccination program. METHODS: Subjects were prospectively recruited (April-October 2017). Case patients were children aged ≤16 years admitted to 11 hospitals with an acute respiratory illness and laboratory-confirmed influenza. Controls were hospitalized with acute respiratory illness and tested negative for influenza. VE estimates were calculated using the test-negative design. RESULTS: A total of 1268 children were hospitalized with influenza: 31.5% were <2 years old, 8.3% were indigenous, and 45.1% had comorbid conditions predisposing to severe influenza. Influenza B was detected in 34.1% with influenza A/H1N1 and A/H3N2 detected in 47.2% and 52.8% of subtyped influenza A specimens. The median length of stay was 3 days (interquartile range, 1-5), 14.5% were admitted to the intensive care unit, and 15.9% received oseltamivir. Four in-hospital deaths occurred (0.3%): one was considered influenza associated. Only 17.1% of test-negative-controls were vaccinated. The VE of inactivated quadrivalent influenza vaccine for preventing hospitalized influenza was estimated at 30.3% (95% confidence interval, 2.6%-50.2%). CONCLUSIONS: Significant influenza-associated morbidity was observed in 2017 in Australia. Most hospitalized children had no comorbid conditions. Vaccine coverage and antiviral use was inadequate. Influenza vaccine was protective in 2017, yet VE was lower than previous seasons. Multiple Australian states have introduced funded preschool vaccination programs in 2018. Additional efforts to promote vaccination and monitor effectiveness are required.
Authors: Huiying Chua; Shuo Feng; Joseph A Lewnard; Sheena G Sullivan; Christopher C Blyth; Marc Lipsitch; Benjamin J Cowling Journal: Epidemiology Date: 2020-01 Impact factor: 4.822
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