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PharmacoEconomics
Published in: PharmacoEconomics 8/2008

01-08-2008 | Original Research Article

Demand Forecasting for Preventive AIDS Vaccines

Economic and Policy Dimensions

Authors: Robert Hecht, Mr Gian Gandhi

Published in: PharmacoEconomics | Issue 8/2008

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Abstract

Background

An AIDS vaccine could play a very significant role in reversing the HIV pandemic, saving millions of lives. For a vaccine to have such an impact, it must be widely available and adopted and taken up rapidly in the countries most affected. A demand-forecasting model provides a valuable tool that can guide R&D spending decisions and identify policy actions to help achieve these goals.

Objective

To identify the key determinants of vaccine demand, model global adoption and uptake dynamics, estimate potential demand and revenues associated with future preventive AIDS vaccines, and to conduct sensitivity analyses to assess the impact of each parameter on demand.

Methods

A discrete, deterministic, linear, predictive mathematical model based on stratified population averages with a 30-year time horizon was developed to assess scenarios of future demand. This forecasting model was used to explore the effects of vaccine characteristics and a variety of regulatory, political, financial and health service factors on future demand and revenues.
The intervention modelled was a preventive AIDS vaccine (efficacy: 30–90%; duration of protection: 3–5 years; in a two-dose prime-boost combination). The main outcome measure was the number of complete courses of vaccine administered.

Results

The model suggests that demand for a preventive AIDS vaccine with a medium efficacy (50%) and duration of protection (3 years) would average 68 million courses annually over a 30-year period. Under different scenarios, demand would peak at 38–152 million courses annually. On the basis of tiered pricing across public and private markets ($US2–100 per dose), these levels of peak demand would translate into $US2.5–5.5 billion in peak annual sales revenues.
Private markets and high-income countries account for small volumes but large shares of projected revenues, while low-income countries account for large volumes and more modest, but still significant, sales revenues. Vaccinations to ‘catch-up’ those who are missed or not eligible for routine annual programmes (whether adolescent or high-risk populations) would account for 20–35% of cumulative vaccination courses across all scenarios.
Demand was found to be sensitive to vaccine efficacy, duration of protection and price. Efforts to expedite regulatory review processes, improve immunization infrastructure and reduce political constraints could increase demand for an AIDS vaccine by 40 million additional courses a year compared with the medium efficacy (baseline) vaccine forecast.

Conclusions

Our model can provide vaccine developers with credible estimates of market potential for an AIDS vaccine, and with a tool that can be used to improve forecasts over time as AIDS vaccine science progresses. It can also help governments to identify and pursue those policies that could best strengthen demand and uptake of a safe and effective preventive AIDS vaccine.
Footnotes
1
Eighty stakeholder interviews were conducted across the world, surveying policy makers and influencers of policy; namely, government advisers and civil servants, academics, non-government organization personnel, pharmaceutical executives and vaccine researchers. The perceptions/preferences of each stakeholder group were sought with respect to the likely characteristics (including price) of a first-generation AIDS vaccine, the associated vaccination strategy that would be employed, and the likely effectiveness (reach/coverage) of such strategies. This helped define country/regional inputs with respect to particular drivers of demand. For a full list of interviewees and collaborators see the International AIDS Vaccine Initiative[2].
 
2
The year of licensure is an assumption made within the model — the chosen year is hypothetical, yet it is necessary to specify it because the year is a crucial determinant of the size of populations around the world who might be targeted for vaccination.
 
3
We defined an efficacy of 50% as implying that for every ten people vaccinated, five would be fully protected against HIV no matter how risky their behaviour. This is known as ‘take-type’ efficacy in that the vaccine ‘takes’ or has an effect in a proportion of those vaccinated. Researchers have considered other definitions of efficacy for HIV vaccines (e.g. ‘degree-type’ efficacy);[4,26,27] however, for the purposes of our stakeholder interviews, we chose the simpler and cognitively intuitive definition.
 
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Metadata
Title
Demand Forecasting for Preventive AIDS Vaccines
Economic and Policy Dimensions
Authors
Robert Hecht
Mr Gian Gandhi
Publication date
01-08-2008
Publisher
Springer International Publishing
Published in
PharmacoEconomics / Issue 8/2008
Print ISSN: 1170-7690
Electronic ISSN: 1179-2027
DOI
https://doi.org/10.2165/00019053-200826080-00005

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