The Epidemiological Impact of anHIV/AIDS Vaccine in Developing Countries

Stover, John ; Garnett, Geoff P. ; Seitz, Steve ; Forsythe, Steven

World Bank, Washington, D.C.

关键词: ADOLESCENCE;    ADOLESCENT;    ADULT POPULATION;    AGED;    AIDS EPIDEMIC;   

DOI  :  10.1596/1813-9450-2811
RP-ID  :  WPS2811

学科分类：社会科学、人文和艺术（综合）

来源: World Bank Open Knowledge Repository

【 摘 要 】

Many people see an effective preventiveAIDS vaccine as the best solution to the HIV/AIDS pandemic.Ten years ago many scientists had hoped that a vaccine wouldbe available by now. Most scientists are still optimisticthat vaccines will be developed and many candidates arebeing tested. Strategies to implement HIV/AIDS vaccinationneed to be developed to be ready when vaccines do becomeavailable. The nature of those programs will depend on thecharacteristics of each vaccine. How much does it cost? Howeffective is it? How long does protection last? The answersto these and other questions will help determine issues suchas: What will be the impact of the vaccine on the epidemic?Who should be vaccinated? Will an AIDS vaccine be morecost-effective than other prevention measures? Will othermeasures still be necessary? What will happen to theepidemic if vaccination leads to riskier behavior? How muchfunding will be needed? The authors use two computersimulation models to investigate the effects of variousvaccine characteristics and implementation strategies on theimpact and cost-effectiveness of vaccines in differentcontexts. A simulation model is applied to data from ruralZimbabwe and the iwgAIDS model is applied to Kampala(Uganda) and Thailand. The models are used to investigatethe effects of efficacy, duration, cost, and type ofprotection on impact and cost-effectiveness. The models alsoshow the merits of targeting public subsidies to variouspopulation groups: all adults, teenagers, high-risk groups,and women of reproductive age. The impact of vaccines on theepidemic is compared with the impact of other preventioninterventions such as condom use and behavior change.Finally, the models are used to explore the extent withwhich behavioral reversals may erode the positive benefitsof the vaccine. A highly effective, long-lasting,inexpensive vaccine would be ideal and could make a majorcontribution in controlling the HIV/AIDS pandemic. Butvaccines that do not attain this ideal can still be useful.A vaccine with 50 percent efficacy and 10 years durationsupplied to 65 percent of all adults could reduce HIVincidence by 25 to 60 percent, depending on the context andstage of the epidemic. Better efficacy and longer durationwould provide even more impact. Programs focused onteenagers or high-risk populations have less overall impactbut would provide significant benefits at much less costthan those reaching all adults. Behavioral reversals coulderode much of the benefits of vaccination programs so itwill be important to combine vaccination with continuedmessages about the importance of safe behaviors. The cost ofthe vaccines is not known at this time. At a cost of $10 or$20 per person vaccinated, the cost per infection avertedwould be as low or lower than other preventioninterventions. Higher costs for the vaccines and the needfor many booster shots could reduce the cost-effectiveness significantly.