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of prevention technologies expanding, but no 'magical solution'
Edwin J. Bernard
August 23, 2006
Now that a vaccine
against HIV is not expected within the next decade, an expanding
array of other prevention technologies - which now includes microbicides,
male circumcision, cervical barriers, PrEP, and genital herpes suppression
- were extensively debated at the Sixteenth International AIDS Conference
held in Toronto last week, but there remain an array of practical
and ethical challenges to research and implementation, according
to the Global HIV Prevention Working Group, co-chaired by Dr Helene
Gayle, who also co-chaired the Conference.
"The data we are
seeing this week highlight the urgent need to accelerate prevention
research in order to study all reasonable strategies and expand
the number of options available to us," she said, adding that "we
must also seize the opportunity that treatment scale-up presents
to integrate prevention programmes into new and evolving systems
of HIV care."
Tuesday's plenary, Prevention: proven approaches and new technologies,
Dr. Cristina Pimenta of the Brazilian Interdisciplinary AIDS Association
warned against the "particularly worrisome" tendency to see biomedical
interventions as "quick" and "magical solutions to HIV/AIDS prevention"
which "deflect or redirect attention away from the fundamentally
political barriers that have been erected in recent years by some
governments and agencies impeding the implementation of proven effective
educational approaches, such as condom use and harm reduction."
Rather, she argued,
they "should be considered as complementary preventive measures
for the transmission of HIV but not a stand alone or absolute solution."
Dr Pimenta also suggested that the most effective prevention programmes
emphasise community empowerment and ensure access to tools - like
condoms and harm-reduction for injecting drug users - that are scientifically
proven to reduce the risk of HIV transmission.
Dr Gita Ramjee
of the South African Medical Research Council, who provided an overview
of current and future prevention technologies, also emphasised that
prevention cannot exist in a cultural and political vacuum and said
that the best way forward is "the synergistic use of social, behavioural,
biomedical and barrier methods," which "can only happen with community
involvement and leadership at all levels."
She also noted
that HIV prevention research faces significant financial, logistical,
and ethical obstacles that, if not quickly addressed, could delay
the completion of critical clinical trials. "Trials of potential
microbicides and other new HIV prevention approaches are hugely
complex undertakings," she said. "We face challenges on
a number of fronts - the world's ability to conduct these trials
is reaching maximum capacity, and current clinical trial ethical
guidelines were not written with today's HIV prevention research
outlined a number of approaches to HIV prevention that have been
in use over the past two decades. These include the use of male
and female condoms; voluntary counselling and testing; the prevention
of mother-to-child transmission; harm-reduction, such as needle
exchange; and behavioural interventions, known as the 'AB' part
of 'ABC' - abstain and be faithful.
She then proceeded
to outline other biomedical prevention technologies that may soon
expand the limited alphabet approach. "I would like to believe that
HIV prevention soon will be more than 'ABC'," she said. "We will
add one more 'C' for circumcision. We will add 'D' for diaphragm,
'E' for [pre- and post-exposure prophylaxis; 'F' for female controlled
microbicides; 'G' for genital tract infection control; 'H' for HSV-2
suppression; and 'I' for immunity by vaccines."
circumcision was one of the most discussed topics at the Toronto
conference, and the focus of several presentations examining both
the efficacy and cost-effectiveness of implementation in sub-Saharan
It also made headlines
around the world when President Clinton spoke about the need to
overcome the obstacles to scaling-up male circumcision in populations
where it is currently not considered acceptable on cultural or religions
grounds. "Should this be shown to be effective," he told the conference,
"we will have another means to prevent the spread of the disease
and to save lives, and we will have a big job to do. It is important
that as we leave here we all be prepared for a green light that
could have a staggering impact on the male population but that will
be frankly a lot of trouble to get done."
over male circumcision is on based on trial results from South Africa
which were first presented a year ago at the Third International
IAS Conference on HIV Pathogenesis and Treatment in Rio de Janeiro.
However, results of three further clinical trials from Uganda and
Kenya will be available in 2007 and 2008.
However, not everyone
is convinced that circumcision is a worthwhile prevention tool.
One of the few dissenting voices came from a study via Way and colleagues
that used demographic data to examine the association between male
circumcision and HIV infection in eight sub-Saharan African countries.
It found that in most countries there was a higher prevalence of
HIV infection amongst circumcised men, and that circumcision was
only significantly protective in Kenya.
Methods for Improving Reproductive Health in Africa (MIRA) study
is currently examining whether the use of a cervical barrier, or
diaphragm - in this case the Ortho All-Flex diaphragm containing
Replens gel (an acidifying buffer) - can prevent HIV infection in
5445 HIV-negative women. The study is taking place at four sites
in two countries, South Africa and Zimbabwe, and is funded by USAID/Gates
Foundation. Dr Ramjee is the principal investigator at two of the
sites that are run by the Medical Research Council of South Africa.
basis is that the upper genital tract may be susceptible to HIV
infection so if you cover the cervix then you may reduce the risk
of HIV infection," she told the conference. "The trial recruitment
is complete and the study is going to end next month. We are hoping
the results will be out in June 2007."
was much excitement and coverage of pre-exposure prophylaxis (PrEP)
in Toronto, based on the preliminary results of a study from Family
Health International which hinted that PrEP might work in humans.
Three further oral tenofovir (Viread) PrEP trial are currently enrolling:
one in male and female Thai IDUs; one in high-risk women in West
Africa; and one in gay men in the United States.
studies have shown that the dual combination drug Truvada, which
contains tenofovir and FTC could be more effective and the protocols
of two new PrEP studies - in young men and women in a very high
prevalence region of Botswana, and in men who have sex with men
in Peru - have been altered to include this drug instead.
There are many
questions about scaling-up PrEP, not least whether it actually works.
Despite the current lack of availability of tenofovir and Truvada
for use as anti-HIV therapy in low-and middle-income countries,
several studies found that it may well be cost-effective if used
Dr Ramjee also
pointed out that there are many other unanswered questions. "Will
it lead to resistant virus for future therapy options?" she wondered.
"What is the level of the adherence required? Would it be acceptable
for otherwise healthy people to take chronic medication? Is there
potential for abuse of PrEP among those people who refuse to and
do not want to use condoms."
few new data were presented at the conference on vaginal and rectal
microbicides, they emerged as one of the biggest prevention stories
of the conference, thanks to the publicity given to them by Bill
and Melinda Gates at the opening ceremony.
The first microbicides
could be available as soon as 2010, noted Dr Ramjee, which is many
years before a preventative vaccine would be available. "There is
urgent need for HIV prevention among women and microbicides would
do just that," she added.
She added that
there are currently between 30 and 40 microbicides candidates in
preclinical development; fourteen in early safety trials and five
in clinical, large-scale efficacy trials, the majority of which
have been conducted in sub-Saharan Africa. Some of the first results
will be presented before the end of 2007.
(For much more
detail on current and developing microbicides see aidsmap's extensive
reports from Microbicides 2006, held in Cape Town, South Africa
use of antiviral drugs such as aciclovir to prevent genital herpes
(HSV-2) recurrences is now being seen as a possible large-scale
prevention strategy. The conference heard results from a French
study conducted in Burkina Faso which found that daily valaciclovir
significantly decreased HIV viral load in the blood and genital
secretions of women not on anti-HIV treatment and of women receiving
Two further large
placebo-controlled trials are currently examining HSV-2 suppressive
therapy. One (HPTN O39) examines the effect of daily aciclovir on
susceptibility to HIV acquisition in 3277 HIV-negative women and
gay men at nine global sites, and is funded by the US National Institutes
of Health. Results are expected next year.
The other (Partners
in Prevention) also uses daily aciclovir and this time includes
3000 sero-different couples (where one partner is HIV-positive at
enrolment) at fourteen sites in sub-Saharan Africa. Enrolment is
70% complete, so results are not expected until 2008, possibly at
the next International AIDS Conference in Mexico City.
of these approaches are examined in greater detail in a report from
the Global HIV Prevention Working Group entitled, New Approaches
to HIV Prevention: Accelerating Research and Ensuring Future Access,
which can be downloaded in full here. The Working Group includes
leading public health experts, clinicians, researchers, and people
affected by HIV/AIDS, and is co-convened by the Henry J Kaiser Family
Foundation and the Bill & Melinda Gates Foundation.
The report's authors
expand on Dr Pimenta's concern that the world is unprepared to ensure
widespread access for these new prevention technologies, and recommend
that individual countries, international agencies, and major donor
organisations need to prepare now for the immediate rollout of any
of the new HIV prevention approaches once they are proven effective
in clinical trials. They recommend that major new donor funding
will be needed to pay for the prevention tools, train healthcare
providers, conduct public education campaigns, and monitor effectiveness.
The report also
emphasises the importance of using new prevention approaches in
combination with existing prevention strategies.
A et al. Is male circumcision protective of HIV infection? Sixteenth
International AIDS Conference, Toronto, abstract TuPe0401, 2006.
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