The Epidemiological Impact of an HIV/AIDS Vaccine in Developing Countries
Many people see an effective preventive AIDS vaccine as the best solution to the HIV/AIDS pandemic. Ten years ago many scientists had hoped that a vaccine would be available by now. Most scientists are still optimistic that vaccines will be develop...
| Main Authors: | , , , |
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| Format: | Policy Research Working Paper |
| Language: | English en_US |
| Published: |
World Bank, Washington, D.C.
2013
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| Subjects: | |
| Online Access: | http://documents.worldbank.org/curated/en/2002/03/1744002/epidemiological-impact-hivaids-vaccine-developing-countries http://hdl.handle.net/10986/14818 |
| Summary: | Many people see an effective preventive
AIDS vaccine as the best solution to the HIV/AIDS pandemic.
Ten years ago many scientists had hoped that a vaccine would
be available by now. Most scientists are still optimistic
that vaccines will be developed and many candidates are
being tested. Strategies to implement HIV/AIDS vaccination
need to be developed to be ready when vaccines do become
available. The nature of those programs will depend on the
characteristics of each vaccine. How much does it cost? How
effective is it? How long does protection last? The answers
to these and other questions will help determine issues such
as: What will be the impact of the vaccine on the epidemic?
Who should be vaccinated? Will an AIDS vaccine be more
cost-effective than other prevention measures? Will other
measures still be necessary? What will happen to the
epidemic if vaccination leads to riskier behavior? How much
funding will be needed? The authors use two computer
simulation models to investigate the effects of various
vaccine characteristics and implementation strategies on the
impact and cost-effectiveness of vaccines in different
contexts. A simulation model is applied to data from rural
Zimbabwe and the iwgAIDS model is applied to Kampala
(Uganda) and Thailand. The models are used to investigate
the effects of efficacy, duration, cost, and type of
protection on impact and cost-effectiveness. The models also
show the merits of targeting public subsidies to various
population groups: all adults, teenagers, high-risk groups,
and women of reproductive age. The impact of vaccines on the
epidemic is compared with the impact of other prevention
interventions such as condom use and behavior change.
Finally, the models are used to explore the extent with
which behavioral reversals may erode the positive benefits
of the vaccine. A highly effective, long-lasting,
inexpensive vaccine would be ideal and could make a major
contribution in controlling the HIV/AIDS pandemic. But
vaccines that do not attain this ideal can still be useful.
A vaccine with 50 percent efficacy and 10 years duration
supplied to 65 percent of all adults could reduce HIV
incidence by 25 to 60 percent, depending on the context and
stage of the epidemic. Better efficacy and longer duration
would provide even more impact. Programs focused on
teenagers or high-risk populations have less overall impact
but would provide significant benefits at much less cost
than those reaching all adults. Behavioral reversals could
erode much of the benefits of vaccination programs so it
will be important to combine vaccination with continued
messages about the importance of safe behaviors. The cost of
the vaccines is not known at this time. At a cost of $10 or
$20 per person vaccinated, the cost per infection averted
would be as low or lower than other prevention
interventions. Higher costs for the vaccines and the need
for many booster shots could reduce the cost-effectiveness significantly. |
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