The effectiveness of influenza vaccination in preventing hospitalisation in children in Western Australia

Christopher C Blyth; Allen C Cheng; Carolyn Finucane; Peter Jacoby; Paul V Effler; David W Smith; Heath Kelly; Kristine K Macartney; Peter C Richmond

doi:10.1016/j.vaccine.2015.10.122

The effectiveness of influenza vaccination in preventing hospitalisation in children in Western Australia

Vaccine. 2015 Dec 16;33(51):7239-7244. doi: 10.1016/j.vaccine.2015.10.122. Epub 2015 Nov 6.

Authors

Christopher C Blyth¹, Allen C Cheng², Carolyn Finucane³, Peter Jacoby³, Paul V Effler⁴, David W Smith⁵, Heath Kelly⁶, Kristine K Macartney⁷, Peter C Richmond⁸

Affiliations

¹ School of Paediatrics and Child Health, University of Western Australia, Perth, Australia; Department of Infectious Diseases, Princess Margaret Hospital for Children, Perth, Australia; Department of Microbiology, PathWest Laboratory Medicine WA, Princess Margaret Hospital for Children, Perth, Australia; Wesfarmers Centre for Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth, Australia. Electronic address: christopher.blyth@uwa.edu.au.
² Infection Prevention and Healthcare Epidemiology Unit, Alfred Health, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia.
³ Wesfarmers Centre for Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth, Australia.
⁴ Communicable Disease Control Directorate, WA Department of Health, Perth, Australia.
⁵ School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Australia; Department of Microbiology, QEII Medical Centre, PathWest Laboratory Medicine WA, Perth, Australia.
⁶ Victorian Infectious Diseases Reference Laboratory, Melbourne, Australia; Australian National University, Canberra, Australia.
⁷ National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, University of Sydney, Sydney, Australia; Children's Hospital Westmead, University of Sydney, Sydney, Australia.
⁸ School of Paediatrics and Child Health, University of Western Australia, Perth, Australia; Wesfarmers Centre for Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth, Australia; Department of General Paediatrics, Princess Margaret Hospital for Children, Perth, Australia.

PMID: 26549359
DOI: 10.1016/j.vaccine.2015.10.122

Abstract

Background: There is increasing evidence demonstrating influenza vaccine effectiveness (VE) in the prevention of influenza in children, including the very young. Data demonstrating the effectiveness against severe disease, including hospitalisation, are limited. We aimed to determine the VE of the southern hemisphere trivalent inactivated influenza vaccine (TIV) in preventing laboratory-confirmed influenza-associated hospitalisation in children.

Patients and methods: Laboratory records were used to identify children with confirmed influenza hospitalised (i.e., cases) during a 5 year period (2008, 2010-2013) at the only tertiary paediatric facility in Western Australia. Cases and time, age and ward matched controls were retrospectively reviewed to determine risk factors, vaccination status and outcome. Adjusted odds ratios and VE estimates were derived using conditional logistic regression models.

Results: Three hundred and eighty five cases were identified (Influenza A, 64.9%; Influenza B, 35.1%). Influenza-like illness and pneumonia were the most frequent presentation (74.5% and 23.9%, respectively). The median length of stay was 2 days (Interquartile range 1-4 days). Twenty children (5.2%) required admission to the intensive care unit. Vaccine uptake in cases and controls was low (4.9% and 8.5%, respectively). Three hundred and six case-control pairs were included in the VE analysis, of which 19 pairs were informative with discrepant vaccination status. VE (fully vaccinated vs. unvaccinated) was estimated to be 62.3% (95% CI: -6.6%, 86.7%).

Conclusion: In this study, the point estimate for the effectiveness of TIV in preventing influenza-associated hospitalisation in children was similar to that reported for emergency or outpatient attended, laboratory-confirmed influenza, yet confidence intervals were wide. Vaccine uptake remains low. Studies, enroling larger numbers of children, ideally with higher vaccine uptake, are needed to provide additional evidence on TIV protection against influenza hospitalisation in children.

Keywords: Influenza; Influenza vaccine; Vaccine effectiveness.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adolescent
Child
Child, Preschool
Female
Hospitalization*
Humans
Infant
Infant, Newborn
Influenza Vaccines / administration & dosage*
Influenza Vaccines / immunology
Influenza, Human / prevention & control*
Male
Retrospective Studies
Tertiary Care Centers
Treatment Outcome
Vaccination / statistics & numerical data
Vaccines, Inactivated / administration & dosage
Vaccines, Inactivated / immunology
Western Australia / epidemiology

Substances

Influenza Vaccines
Vaccines, Inactivated