Influenza vaccination in Western Australian children: Exploring the health benefits and cost savings of increased vaccine coverage in children

Christopher C Blyth; Parveen Fathima; Rebecca Pavlos; Peter Jacoby; Olivia Pavy; Elizabeth Geelhoed; Peter C Richmond; Paul V Effler; Hannah C Moore

doi:10.1016/j.jvacx.2023.100399

Influenza vaccination in Western Australian children: Exploring the health benefits and cost savings of increased vaccine coverage in children

Vaccine X. 2023 Oct 18:15:100399. doi: 10.1016/j.jvacx.2023.100399. eCollection 2023 Dec.

Authors

Christopher C Blyth^{1

2

3

4}, Parveen Fathima^{1

5}, Rebecca Pavlos¹, Peter Jacoby⁶, Olivia Pavy¹, Elizabeth Geelhoed⁶, Peter C Richmond^{1

2

7

8}, Paul V Effler⁹, Hannah C Moore^{1

10}

Affiliations

¹ Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth, WA, Australia.
² School of Medicine, University of Western Australia, Perth, WA, Australia.
³ Department of Infectious Diseases, Perth Children's Hospital, Perth, WA, Australia.
⁴ Department of Microbiology, PathWest Laboratory Medicine, QEII Medical Centre, Perth, WA, Australia.
⁵ School of Public Health, University of Sydney, Sydney, New South Wales, Australia.
⁶ Telethon Kids Institute, Perth Children's Hospital, Perth, WA, Australia.
⁷ Department of Immunology, Perth Children's Hospital, Perth, WA, Australia.
⁸ Department of General Paediatrics, Perth Children's Hospital, Perth, WA, Australia.
⁹ Communicable Disease Control Directorate, Department of Health, Perth, WA, Australia.
¹⁰ School of Population Health, Curtin University, Perth, Western Australia, Australia.

Abstract

Introduction: To assess potential benefits and direct healthcare cost savings with expansion of an existing childhood influenza immunisation program, we developed a dynamic transmission model for the state of Western Australia, evaluating increasing coverage in children < 5 years and routinely immunising school-aged children.

Methods: A deterministic compartmental Susceptible-Exposed-Infectious-Recovered age-stratified transmission model was developed and calibrated using laboratory-notification and hospitalisation data. Base case vaccine coverage estimates were derived from 2019 data and tested under moderate, low and high vaccine effectiveness settings. The impact of increased coverage on the burden of influenza, influenza-associated presentations and net costs were assessed using the transmission model and estimated health utilisation costs.

Results: Under base case vaccine coverage and moderate vaccine effectiveness settings, 225,460 influenza cases are expected annually across all ages. Direct healthcare costs of influenza were estimated to be A$27,608,286 per annum, dominated by hospital costs. Net cost savings of >$A1.5 million dollars were observed for every 10 % increase in vaccine coverage in children < 5 years. Additional benefits were observed by including primary school age children (5-11 years) in the funded influenza vaccination program - a reduction in cases, presentations, hospitalisations and approximately $A4 million net costs savings were observed for every 10 % increase in coverage. The further addition of older children (12-17 years) resulted in only moderate additional net cost savings figures, compared with a 5-11year-old program alone. Net costs savings were predominantly derived by a reduction in influenza-associated hospitalisation in adults.

Conclusions: Any increase in influenza vaccine coverage in children < 5 years, above a base case of 50 % coverage resulted in a substantive reduction in influenza cases, presentations, hospitalisations and net costs when applied to the West Australian population. However, the most impactful pediatric program, from both a disease prevention and costs perspective, would be one that increased vaccination coverage among primary-school aged children.

Keywords: Child; Costs; Influenza; Influenza vaccination.