Male circumcision, cervical barriers such as the diaphragm, pre-exposure prophylaxis with anti-retrovirals and herpes suppression ‘ all prevention approaches in the late stages of clinical research ‘ have got prevention practitioners excited.
For long the ABC has been the main armor in the prevention battle, including in South Africa.
But researchers warn that none of the new methods, which could also in the future include microbicides and vaccines, are the only ‘magic bullet’ for HIV prevention.
None of the new prevention methods currently being tested is likely to be 100 percent effective. All will need to be used in combination with existing approaches, such as condoms, if they are to reduce the global burden of HIV/AIDS.
But the Global HIV Prevention Working Group (GHPWG) has warned that there are serious obstacles, particularly a lack of resources, that could delay or derail these critical prevention trials.
The Group, which includes the University of KwaZulu-Natal’s Professor Salim Abdool Karim and Professor Malegapuru Makgoba and Dr Nono Simelela (South Africa’s former AIDS chief), said other obstacles included a lack of capacity to launch and complete trials and ethical concerns.
These ethical concerns include how the existing ABC prevention methods should be presented to all trial participants, ensuring proper informed consent and determining how to facilitate HIV treatment for participants test HIV positive at the initial screening or who become HIV infected during a trial.
‘The world is unprepared to capitalize on the potential success of prevention research currently underway. Very little has been done to mobilize resources and develop the public health guidance, provider training, and public education needed to ensure rapid implementation of new prevention methods,’ said the GHPWG in a report released at the conference.
A long established and highly effective prevention programme, the prevention of mother to child transmission, has been provided to only nine percent of pregnant HIV positive women (according to UNAIDS).
The first randomised efficacy trial of male circumcision for HIV prevention was conducted in South Africa and showed that circumcised men were 60 percent less likely than uncircumcised men to become infected with HIV from female partners.
Three additional efficacy trials of male circumcision are underway in Kenya and Uganda to assess the applicability of the South African findings in other settings and in larger populations, and to determine if male circumcision also reduces the risk of HIV transmission from men to their female partners. Results are expected next year.
An efficacy trial of the diaphragm is also nearing completion in South Africa and Zimbabwe with results expected next year, Researchers hypothesize that cervical barriers such as the diaphragm (currently used for contraception) may help protect women from HIV and other sexually transmitted diseases.
‘If it works, the challenge will be to make the diaphragm acceptable and available,’ said Judith Auerbach, vice-president at amFAR, The Foundation for AIDS Research.
Although still in the early stages, pre-exposure prophylaxis (Prep) has got researchers excited. Research in animals suggests that antiretroviral drugs used for HIV treatment may also be effective in preventing infection in HIV-uninfected adults.
Efficacy trials of this approach are underway in Botswana (among heterosexual couples in which one partner is also HIV infected), Peru (men who have sex with men) and Thailand (injecting drug users) with results available at the end of next year or 2008.
Herpes, which infects up to 70 percent of people in some parts of sub-Saharan Africa, can triple the risk of HIV acquisition as well as increase the transmission to others. Figures show that 63,5% (24,5-m of 38,6-m) of HIV infected individuals live in sub-Saharan Africa.
The inexpensive, off-patent drug acyclovir is approved for herpes suppression, and two trials are being conducted in Africa (including South Africa), Latin America and the United States to test whether suppressing herpes lowers HIV risk. Results are expected in the next two years.
More established prevention methods into microbicides (a vaginal barrier gel) and an HIV vaccine are still ongoing, but results are as far as 10 years away. The first microbicide trial results could be available by 2008.