Elsevier

Vaccine

Volume 26, Issue 17, 16 April 2008, Pages 2142-2153
Vaccine

The cost-effectiveness of a universal influenza vaccination program for adults aged 50–64 years in Australia

https://doi.org/10.1016/j.vaccine.2008.01.050Get rights and content

Summary

Currently the Australian government funds universal influenza vaccine for all those aged ≥65 years under the National Immunisation Program (NIP). Annual vaccination rates in those aged 50–64 years are significantly lower than vaccination rates in those aged ≥65 years, and currently less than half those at high-risk of influenza-related complications aged 50–64 years are immunised. This study used a decision tree model to examine the cost-effectiveness of lowering the age threshold for the influenza NIP in Australia to include those aged 50–64 years. From a healthcare payer perspective, a new influenza vaccination policy would cost $8908/QALY gained. From a societal perspective, a new influenza vaccination policy would cost $8338/QALY gained. From a governmental perspective, a new influenza vaccination policy would cost $22,408/QALY gained. The most influential parameters in deterministic sensitivity analysis included: probability of death due to influenza, vaccine efficacy against mortality, vaccine uptake, vaccine cost, and vaccine administration cost. Influenza vaccination for people aged 50–64 years appears highly cost-effective, and should be a strong candidate for funding under the NIP.

Introduction

Influenza is a common viral infection causing significant morbidity and mortality. It is responsible for 2886 hospitalisations and 196 deaths annually amongst Australians aged 50–64 years [1]. Those with underlying risk factors, such as diabetes, cardiovascular disease, chronic respiratory disease, or weakened immune systems are particularly susceptible to influenza complications and mortality. Influenza vaccination offers an effective means of preventing much of this morbidity and mortality.

The National Health and Medical Research Council (NHMRC) recommends vaccination of all individuals aged ≥65 years, individuals (of any age) at increased risk of influenza-related complications, and contacts of high-risk (HR) patients [2]. However, the Australian government only funds influenza vaccine for those aged ≥65 years and Indigenous people aged ≥50 years under the National Immunisation Program (NIP) [3]. No government funded NIP exists for the non-Indigenous population aged 50–64 years, even those for whom vaccine is recommended. These people can purchase influenza vaccine privately or at reduced cost via the government-subsidised Pharmaceutical Benefits Scheme (PBS) [3].

A growing body of evidence indicates vaccination of healthy adults is often cost-saving [4], [5], [6]. Recently, the cost-effectiveness of universal influenza vaccination in those aged 50–64 years in Europe reported favourable results [7], [8], [9].

In the US, the Advisory Committee on Immunization Practices (ACIP) recommends vaccination for all persons aged 50–64 years as a way of increasing vaccination uptake in persons with HR conditions [10]. The ACIP argues that age-based vaccine strategies are more successful than targeting those at HR, and that those without HR conditions still benefit from vaccination [10].

Over one quarter of Australians aged 50–64 years are considered to be at HR of influenza-complications [3]. This age-group achieves annual vaccination rates of approximately 33% (with less than half those at HR being immunised) [3], significantly lower than the 79% influenza vaccination rate achieved under the NIP for Australians aged ≥65 years [3]. Similar vaccination coverage could potentially be achieved in the 50–64 year age-group if the NIP was extended to this group. Given the difficulties identifying and targeting those at HR, lowering the age threshold offers a pragmatic approach to increasing coverage levels in Australia [7]. However, the potential benefits of extending the NIP are not without costs. This study examines the cost-effectiveness of universal vaccination funding for Australians aged 50–64 years.

Section snippets

Methods

A decision tree model (adapted from Aballea et al. [7]) was used to evaluate the cost-effectiveness of extending universal vaccination funding to Australians aged 50–64 years. The model distinguished between those at HR and those at low-risk (LR) of influenza-related complications (Fig. 1). HR included those with chronic diseases such as diabetes mellitus, circulatory disease, respiratory disease, and those with weakened immune systems [2], [3]. Primary disease was defined as influenza-like

Health outcomes

A vaccination program targeted at 50–64-year-olds would reduce the annual number of ILI cases (medically attended and non-attended) by 3124, a 0.09% reduction in the incidence of ILI, from 1.90 to 1.81%. The new policy would also prevent 1172 hospitalisations, 89 deaths and 2805 work days lost (Table 3).

Costs

From a healthcare payer perspective, a new influenza vaccination policy would cost an additional $15.5 million (or an additional $4.40 per person aged 50–64 years). A total of $0.1 million would

Discussion

The incremental cost per QALY gained was less than $9000 from the healthcare payer perspective. This is well below the implied threshold for cost-effectiveness based on past PBAC funding decisions [40]. In the healthcare payer perspective 99% of all simulations were below a cost-effectiveness acceptability threshold of $50,000/QALY gained.

No previously published Australian study has examined the cost-effectiveness of public funding of influenza vaccine in people aged 50–64 years. The Aballea et

Acknowledgements

This research was commissioned by the Influenza Specialist Group. Information in this report has been drawn from data collected by the General Practice Statistics and Classification Unit, the University of Sydney in collaboration with the Australian Institute of Health and Welfare (AIHW). We thank the AIHW for provision of data. AN is funded by a Public Health Postgraduate Scholarship (402920) from the National Health and Medical Research Council (NHMRC) of Australia, and by a GlaxoSmithKline

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