Influenza hospitalizations in Australian children 2010-2019: The impact of medical comorbidities on outcomes, vaccine coverage, and effectiveness

doi:10.1111/irv.12939

. 2022 Mar;16(2):316-327.

doi: 10.1111/irv.12939. Epub 2021 Nov 16.

Influenza hospitalizations in Australian children 2010-2019: The impact of medical comorbidities on outcomes, vaccine coverage, and effectiveness

Daniel A Norman^{1

2}, Allen C Cheng^{3

4}, Kristine K Macartney^{5

6

7}, Hannah C Moore¹, Margie Danchin^{8

9

10}, Holly Seale¹¹, Jocelynne McRae^{5

7}, Julia E Clark¹², Helen S Marshall^{13

14

15}, Jim Buttery^{16

17}, Joshua R Francis^{18

19}, Nigel W Crawford^{8

10

20}, Christopher C Blyth^{1

2

21

22}

Affiliations

¹ Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, Western Australia, Australia.
² School of Medicine, University of Western Australia, Crawley, Western Australia, Australia.
³ Infection Prevention and Healthcare Epidemiology Unit, Alfred Health, Melbourne, Victoria, Australia.
⁴ School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia.
⁵ National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.
⁶ Department of Infectious Diseases and Microbiology, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.
⁷ Discipline of Child and Adolescent Health, Faculty of Medicine, University of Sydney, Sydney, New South Wales, Australia.
⁸ Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia.
⁹ Vaccine Hesitancy, Murdoch Children's Research Institute, Parkville, Victoria, Australia.
¹⁰ Department of General Medicine, The Royal Children's Hospital, Parkville, Victoria, Australia.
¹¹ School of Population Health, University of New South Wales, Randwick, New South Wales, Australia.
¹² Infection Management and Prevention Service, Queensland Children's Hospital, South Brisbane, Queensland, Australia.
¹³ Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia.
¹⁴ Robinson Research Institute, The University of Adelaide, Adelaide, South Australia, Australia.
¹⁵ The Vaccinology and Immunology Research Trials Unit, Women's and Children's Health Network, Adelaide, South Australia, Australia.
¹⁶ Department of Infection and Immunity, Monash Children's Hospital, Monash Health, Clayton, Victoria, Australia.
¹⁷ Monash Centre of Health Care Research and Implementation, Departments of Paediatrics, Monash University, Melbourne, Victoria, Australia.
¹⁸ Royal Darwin Hospital, Top End Health Service, Darwin, Northern Territory, Australia.
¹⁹ Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia.
²⁰ SAFEVIC, Murdoch Children's Research Institute, Parkville, Victoria, Australia.
²¹ Department of Infectious Disease, Perth Children's Hospital, Nedlands, Western Australia, Australia.
²² PathWest Laboratory Medicine, QEII Medical Centre, Nedlands, Western Australia, Australia.

PMID: 34787369
PMCID: PMC8818821
DOI: 10.1111/irv.12939

Influenza hospitalizations in Australian children 2010-2019: The impact of medical comorbidities on outcomes, vaccine coverage, and effectiveness

Daniel A Norman et al. Influenza Other Respir Viruses. 2022 Mar.

. 2022 Mar;16(2):316-327.

doi: 10.1111/irv.12939. Epub 2021 Nov 16.

Authors

Affiliations

¹ Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, Western Australia, Australia.
² School of Medicine, University of Western Australia, Crawley, Western Australia, Australia.
³ Infection Prevention and Healthcare Epidemiology Unit, Alfred Health, Melbourne, Victoria, Australia.
⁴ School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia.
⁵ National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.
⁶ Department of Infectious Diseases and Microbiology, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.
⁷ Discipline of Child and Adolescent Health, Faculty of Medicine, University of Sydney, Sydney, New South Wales, Australia.
⁸ Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia.
⁹ Vaccine Hesitancy, Murdoch Children's Research Institute, Parkville, Victoria, Australia.
¹⁰ Department of General Medicine, The Royal Children's Hospital, Parkville, Victoria, Australia.
¹¹ School of Population Health, University of New South Wales, Randwick, New South Wales, Australia.
¹² Infection Management and Prevention Service, Queensland Children's Hospital, South Brisbane, Queensland, Australia.
¹³ Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia.
¹⁴ Robinson Research Institute, The University of Adelaide, Adelaide, South Australia, Australia.
¹⁵ The Vaccinology and Immunology Research Trials Unit, Women's and Children's Health Network, Adelaide, South Australia, Australia.
¹⁶ Department of Infection and Immunity, Monash Children's Hospital, Monash Health, Clayton, Victoria, Australia.
¹⁷ Monash Centre of Health Care Research and Implementation, Departments of Paediatrics, Monash University, Melbourne, Victoria, Australia.
¹⁸ Royal Darwin Hospital, Top End Health Service, Darwin, Northern Territory, Australia.
¹⁹ Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia.
²⁰ SAFEVIC, Murdoch Children's Research Institute, Parkville, Victoria, Australia.
²¹ Department of Infectious Disease, Perth Children's Hospital, Nedlands, Western Australia, Australia.
²² PathWest Laboratory Medicine, QEII Medical Centre, Nedlands, Western Australia, Australia.

PMID: 34787369
PMCID: PMC8818821
DOI: 10.1111/irv.12939

Abstract

Background: Children with comorbidities are at greater risk of severe influenza outcomes compared with healthy children. In Australia, influenza vaccination was funded for those with comorbidities from 2010 and all children aged <5 years from 2018. Influenza vaccine coverage remains inadequate in children with and without comorbidities.

Methods: Children ≤16 years admitted with acute respiratory illness and tested for influenza at sentinel hospitals were evaluated (2010-2019). Multivariable regression was used to identify predictors of severe outcomes. Vaccine effectiveness was estimated using the modified incidence density test-negative design.

Results: Overall, 6057 influenza-confirmed hospitalized cases and 3974 test-negative controls were included. Influenza A was the predominant type (68.7%). Comorbidities were present in 40.8% of cases. Children with comorbidities were at increased odds of ICU admission, respiratory support, longer hospitalizations, and mortality. Specific comorbidities including neurological and cardiac conditions increasingly predisposed children to severe outcomes. Influenza vaccine coverage in influenza negative children with and without comorbidities was low (33.5% and 17.9%, respectively). Coverage improved following introduction of universal influenza vaccine programs for children <5 years. Similar vaccine effectiveness was demonstrated in children with (55% [95% confidence interval (CI): 45; 63%]) and without comorbidities (57% [(95%CI: 44; 67%]).

Conclusions: Comorbidities were present in 40.8% of influenza-confirmed admissions and were associated with more severe outcomes. Children with comorbidities were more likely experience severe influenza with ICU admission, mechanical ventilation, and in-hospital morality. Despite demonstrated vaccine effectiveness in those with and without comorbidities, vaccine coverage was suboptimal. Interventions to increase vaccination are expected to reduce severe influenza outcomes.

Keywords: comorbidities; hospitalizations; pediatric influenza; vaccination.

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Figures

**FIGURE 1**
(A) Influenza vaccine coverage in influenza test‐positive and test‐negative children by comorbidities:2010–2019. (B) Influenza vaccine coverage in influenza‐negative hospitalized children with and without comorbidities

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References

1. Lafond KE, Nair H, Rasooly MH, et al. Global role and burden of influenza in pediatric respiratory hospitalizations, 1982–2012: a systematic analysis. PLoS Med. 2016;13(3):e1001977 - PMC - PubMed
1. Chiu C, Dey A, Wang H, et al. Vaccine preventable diseases in Australia, 2005 to 2007. Commun Dis Intell Q Rep. 2010;34:S1 - PubMed
1. Gill PJ, Ashdown HF, Wang K, et al. Identification of children at risk of influenza‐related complications in primary and ambulatory care: a systematic review and meta‐analysis. Lancet Respir Med. 2015;3(2):139‐149. - PubMed
1. Kelly PM, Kotsimbos T, Reynolds A, et al. FluCAN 2009: initial results from sentinel surveillance for adult influenza and pneumonia in eight Australian hospitals. Med J Aust. 2011;194(4):169‐174. - PubMed
1. Zurynski Y, McIntyre P, Booy R, Elliott EJ, Group PI . Paediatric active enhanced disease surveillance: A new surveillance system for A ustralia. J Paediatr Child Health. 2013;49(7):588‐594. - PubMed

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[1] Lafond KE, Nair H, Rasooly MH, et al. Global role and burden of influenza in pediatric respiratory hospitalizations, 1982–2012: a systematic analysis. PLoS Med. 2016;13(3):e1001977 - PMC - PubMed

[2] Lafond KE, Nair H, Rasooly MH, et al. Global role and burden of influenza in pediatric respiratory hospitalizations, 1982–2012: a systematic analysis. PLoS Med. 2016;13(3):e1001977 - PMC - PubMed

[3] Chiu C, Dey A, Wang H, et al. Vaccine preventable diseases in Australia, 2005 to 2007. Commun Dis Intell Q Rep. 2010;34:S1 - PubMed

[4] Chiu C, Dey A, Wang H, et al. Vaccine preventable diseases in Australia, 2005 to 2007. Commun Dis Intell Q Rep. 2010;34:S1 - PubMed

[5] Gill PJ, Ashdown HF, Wang K, et al. Identification of children at risk of influenza‐related complications in primary and ambulatory care: a systematic review and meta‐analysis. Lancet Respir Med. 2015;3(2):139‐149. - PubMed

[6] Gill PJ, Ashdown HF, Wang K, et al. Identification of children at risk of influenza‐related complications in primary and ambulatory care: a systematic review and meta‐analysis. Lancet Respir Med. 2015;3(2):139‐149. - PubMed

[7] Kelly PM, Kotsimbos T, Reynolds A, et al. FluCAN 2009: initial results from sentinel surveillance for adult influenza and pneumonia in eight Australian hospitals. Med J Aust. 2011;194(4):169‐174. - PubMed

[8] Kelly PM, Kotsimbos T, Reynolds A, et al. FluCAN 2009: initial results from sentinel surveillance for adult influenza and pneumonia in eight Australian hospitals. Med J Aust. 2011;194(4):169‐174. - PubMed

[9] Zurynski Y, McIntyre P, Booy R, Elliott EJ, Group PI . Paediatric active enhanced disease surveillance: A new surveillance system for A ustralia. J Paediatr Child Health. 2013;49(7):588‐594. - PubMed

[10] Zurynski Y, McIntyre P, Booy R, Elliott EJ, Group PI . Paediatric active enhanced disease surveillance: A new surveillance system for A ustralia. J Paediatr Child Health. 2013;49(7):588‐594. - PubMed

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Influenza hospitalizations in Australian children 2010-2019: The impact of medical comorbidities on outcomes, vaccine coverage, and effectiveness

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Influenza hospitalizations in Australian children 2010-2019: The impact of medical comorbidities on outcomes, vaccine coverage, and effectiveness

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