Annex A
Additional information relating to Q5
The Global Fund has revolutionized access to
treatment for those with HIV/AIDS, but there has not been a concomitant
increase in prevention efforts. There is already a large investment
in HIV vaccine development, but increasing pessimism about the
likelihood of an effective vaccine.1 Greater emphasis should therefore
be put on other forms of prevention of HIV infection.
There is convincing evidence that other sexually
transmitted infections (STIs) enhance the transmission of HIV
during sexual intercourse by enhancing both the vulnerability
of HIV uninfected persons and the infectiousness of HIV infected
persons. The most common STI in sub-Saharan Africa is Herpes
simplex virus type 2 (HSV-2) infection. HSV-2 prevalence
rises steeply with age, reaching rates of more than 70% in women
and 60% in men in some populations.2 People infected with HSV-2
have a three-fold higher risk of acquiring HIV. This effect is
highest following recent HSV-2 infection and is therefore most
important in young people, the group with the highest incidence
of HIV. It has been estimated that 20-50% of HIV infections
may be attributable to HSV-2,2 depending on the prevalence
of HSV-2 infection. An intervention that could reverse this would
have a significant impact.
Treatment of herpes with antiviral drugs shows
potential in reducing the infectiousness of HIV (as well as HSV-2),3
but long-term suppressive therapy is not possible at a population
level. For a feasible and effective population approach, a vaccine
against HSV-2 is needed.
No vaccine is yet available, for both technical
and commercial reasons. Bringing prophylactic vaccines to the
market is a long and costly exercise with uncertain returns. None
of the major global vaccine players (Merck, GSK, Wyeth, Sanofi-Aventis,
Chiron and Baxter) is currently focusing significant vaccine development
efforts on HSV. GSK is collaborating with the NIH/NIAID on a recombinant
gD protein vaccine that has shown some efficacy, but only in women
and only in those who are not infected with HSV-1:4 infection
with HSV-1 is almost universal in Africa.
The most promising vaccine candidate has
been developed by a British biotechnology company. This is
highly effective in pre-clinical studies and safe in early clinical
studies, but due to change of ownership of the company has been
stuck at this stage of development. Targeted action is needed
to further the development of products such as this that are potentially
of major public health importance but are languishing because
of the investment needed and the uncertainty of commercial returns.
REFERENCES
1 Steinbrook R. One step forward, two steps back—will
there ever be an AIDS vaccine? N Engl J Med 2007;357:2653-5.
2 Freeman E E, Weiss H A, Glynn J R, Cross P
L, Whitworth J A, Hayes R J. Herpes simplex virus 2 infection
increases HIV acquisition in men and women: systematic review
and meta-analysis of longitudinal studies. AIDS 2006;20:73-83.
3 Nagot N, Ouedraogo A, Foulongne V, et al.
Reduction of HIV-1 RNA levels with therapy to suppress herpes
simplex virus. N Engl J Med 2007;356(8):790-9.
4 Stanberry L R, Spruance S L, Cunningham A L,
et al. Glycoprotein-D-adjuvant vaccine to prevent genital
herpes. N Engl J Med 2002;347(21):1652-61.
| 
