Demand Forecasting for Preventive AIDS Vaccines
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.
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.
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.
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.
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.
- 1.Sekhri N. Forecasting for global health: new money, new products and new markets [background paper]. Washington, DC: Center for Global Development, 2006Google Scholar
- 2.International AIDS Vaccine Initiative. Forecasting the global demand for preventive HIV vaccines [policy research working paper no. 15]. New York: IAVI, 2007Google Scholar
- 3.International AIDS Vaccine Initiative. Estimating the global impact of an AIDS vaccine [policy research working paper no. 4]. New York: IAVI, 2005Google Scholar
- 4.International AIDS Vaccine Initiative. The impact of an AIDS vaccine in developing countries: a new model and preliminary results [policy research working paper no. 8]. New York: IAVI, 2006Google Scholar
- 5.The United Nations Joint Programme on HTV/AIDS. 2007 AIDS epidemic update. Geneva: UN AIDS, 2007Google Scholar
- 6.International AIDS Vaccine Initiative. Demand for a preventive HIV vaccine: a review of the literature [policy research working paper no. 3]. New York: IAVI, 2005Google Scholar
- 7.Esparza J. Potential vaccination strategies using HIV vaccines in developing countries [background paper; GPA/IFP.4/93.8]. Fourth meeting of the WHO-IFPMA Working Group on the development, testing, utilization and supply of drugs and vaccines for HIV infection and HIV-related disease; 1993 Feb 1–2; GenevaGoogle Scholar
- 8.Bishai D, Lin MK, Kiyonga CWB. Algorithms for purchasing AIDS vaccines [World Bank policy research working paper no. 2321]. Washington, DC: World Bank 2000Google Scholar
- 10.International AIDS Vaccine Initiative. An advance market commitment for AIDS vaccines: accelerating the response from industry [policy research working paper no. 7]. New York: IAVI, 2005Google Scholar
- 11.Shaffer C, Brandewinder M, Wroebel S, et al. Applied strategies: analysis using the AMC-FIRM model. San Mateo (CA): Applied Strategies, 2007. Data on fileGoogle Scholar
- 12.Medicines for Malaria Venture. Planning for success: analysis conducted by the Bill and Melinda Gates Foundation and the Boston Consulting Group. Boston (MA): Medicines for Malaria, 2005 (data on file)Google Scholar
- 13.Longhi A, Chisholm R, Rilling M, et al. Principles for forecasting demand for global health products. Washington, DC: Center for Global Development Forecasting Principles Mini-Group, 2006Google Scholar
- 15.World Health Organization. Selected vaccine introduction status into routine immunization worldwide, 2003. Geneva: WHO, 2003 [online]. Available from URL: http://www.who.int/immunization_monitoring/routine/schedule_analysis_2003.pdf [Accessed 2008 Jan 15]Google Scholar
- 16.International AIDS Vaccine Initiative. Forecasting the global demand for preventive HIV vaccines [policy research working paper no. 15, appendices III-IV]. New York: IAVI, 2007Google Scholar
- 17.Central Intelligence Agency. Age structure/distribution by country [online]. Available from URL: https://www.cia.gov/library/publications/the-world-factbook/index.html [Accessed 2008 Jun 23]
- 18.United Nations Secretariat. Department of Economic and Social Affairs. Population Division. World population prospects: the 2004 revision [online]. Available from URL: http://www.un.org/esa/population/publications/WPP2004/2004Highlights_finalrevised.pdf [Accessed 2008 Jun 23]
- 22.The United Nations Joint Programme on HIV/AIDS. Report on the global AIDS epidemic: annex 1. Country profiles. Geneva: UNAIDS, 2006: 374Google Scholar
- 23.USAID, UNAIDS, WHO, and the POLICY Project. The level of effort in the national response to HIV/AIDS: the AIDS program effort index (API) 2003 round. Washington, DC: USAID, 2003 [online]. Available from URL: http://www.policyproject.com/pubs/monographs/API2003.pdf. [Accessed 2006 Jun 10]Google Scholar
- 24.World Bank. GNI per capita 2005: Atlas method and purchasing power parity [online]. Available from URL: http://siteres ources.worldbank.org/ICPINT/Resources/Atlas_2005.pdf [Accessed 2008 Jun 23]Google Scholar
- 25.The Global Fund to fight AIDS, Tuberculosis and Malaria (GFATM). Resource needs: funding the global fight against HIV/AIDS, tuberculosis and malaria. Resource needs for the global fund 2008–2010. GFATM 2007 [online]. Available from URL: http://www.theglobalfund.org/en/files/about/replenishment/oslo/Resource%20Needs.pdf [Accessed 2006 Aug 22]
- 28.Rogers EM. Diffusion of innovations. 4th ed. New York: The Free Press, 1995: 22–23Google Scholar
- 29.Andre F. How the research-based industry approaches vaccine development and establishes priorities. Developmental biology 2002; 110: 25–29Google Scholar
- 30.International AIDS Vaccine Initiative. Speeding the manufacture of an HIV vaccine: policy issues and options [policy discussion paper]. New York: IAVI, 2005Google Scholar
- 31.Van Exan R. BIOTECanada Vaccine Industry Committee. Current challenges in immunization: the delicate balance of vaccine supply and demand [presentation]. Ottawa (ON): BIOTECanada, 2004 [online]. Available from URL: http://www.phac-aspc.gc.ca/cnic-ccni/2004/pres/_pdf-wed-mec/2_VAN_EXAN_ROB_Wednesday_210ae.pdf [Accessed 2006 Oct 6]Google Scholar
- 32.Cohen J. Shots in the dark: the wayward search for an AIDS vaccine. New York: Norton, 2001Google Scholar
- 33.Kalorama information. Vaccines: the world market. Rockville (MD): Kalorama information, 2007 [online]. Available from URL: http://www.kaloramainformation.com/Vaccines-1351010/ [Accessed 2007 May 5]Google Scholar
- 34.IMS Health. Vaccines: an antidote to sluggish pharma sales? [online]. Available from URL: http://www.imshealth.com/web/end/0,3150,64576068_63872702_82367711,00.html [Accessed 2008 Jun 17]
- 35.Barth-Jones DC, Cheng H, Kang LY, et al. Cost effectiveness and delivery study for future HIV vaccines. AIDS 2005; 19 (13): wl–w6Google Scholar
- 36.Barth-Jones DC, Longini Jr IM. Determining optimal vaccination policy for HIV vaccines: a dynamic simulation model for the evaluation of vaccination policy. In: Anderson JG, Katzper M, editors. Proceedings of the International Conference on Health Sciences Simulation 2002 Western Multiconference; 2002 Jan 27–31; San Antonio (TX): 6–79Google Scholar