JOHANNESBURG, 23 August 2010 (PlusNews) - The recent release of positive results from a microbicide trial in South Africa have kick-started discussions between scientists, activists and community workers about the quickest and most responsible way of getting a product into women's hands.

The trial by the Centre for the AIDS Programme of Research in South Africa (CAPRISA) found that a vaginal gel containing tenofovir, an antiretroviral (ARV) drug, was 39 percent effective at reducing women's risk of contracting HIV during sex.

In other parts of the world, such results might not be cause for celebration, but in South Africa, and particularly in hard-hit KwaZulu-Natal Province, where the trial was conducted, even such partial effectiveness could prevent 1.3 million new HIV infections over the next two decades and avert over 800,000 deaths, according to mathematical modelling.

"The discomfort we all have is that if this [product] is working, shouldn't we be pushing its use as quickly as possible?" said Prof Helen Rees, director of the Reproductive Health and HIV Research Unit (RHRU) of Witwatersrand University, at a meeting about the CAPRISA trial results in Johannesburg.

Representatives from various sectors in South Africa's AIDS community attended the meeting convened by the South African National AIDS Council, RHRU, and the Treatment Action Campaign (TAC), a local lobby group, to discuss the implications of the results.

While some participants raised concerns about whether a female-controlled HIV prevention product might give men an excuse not to use condoms, most wanted to know what the complex trial results would mean for women in their communities, how soon it could be on pharmacy shelves, and what it would cost.

Rees explained that South Africa's regulatory authority, the Medicines Control Council (MCC), will probably demand confirmatory results from a second study before approving registration of a microbicide product containing tenofovir. "It's still possible that some of this result was due to chance," she said.

Three trials of prevention methods using ARVs are ongoing in South Africa. The VOICE trial is testing a tenofovir gel, as well as a daily oral dose of tenofovir, and another ARV called truvada, among 5,000 HIV-negative women from multiple sites in South Africa and elsewhere in Africa.

A trial called FEM-PrEP is also assessing a daily truvada pill for preventing HIV infection in women and a third trial, called iPrEx, is evaluating the same oral regimen of truvada for preventing HIV among men who have sex with men.

But as none of these trials are using the same regimen as the CAPRISA trial, Rees said they were unlikely to produce confirmatory results that could be used to seek product registration.

Larger trial planned

A consortium of six research centres in South Africa is considering repeating the CAPRISA trial on a larger scale, among a wider age group. The CAPRISA trial only included women over the age of 18, so a second study would have to establish that the product was safe for younger women.

A larger multi-site trial could also provide more information about how women in different communities might use the gel, and the relationship between adherence and product effectiveness.

The original trial found that women who used the gel for 80 percent of sex acts had a 54 percent reduced risk of becoming infected with HIV, while women who used it less than half the time only had a 28 percent reduction in risk.

"Different trials will answer different questions, but they won't determine the safety and effectiveness [of a product] in a real world setting," said Thesla Palanee of RHRU.

Rees noted that the extensive HIV counselling and regular testing that women in prevention trials received had a significant impact on their sexual risk-taking behaviour. CAPRISA trial participants, for instance, reported increased condom use and lower levels of sexual activity. "Why can't we do this in the real world?" she asked.

Despite the level of behaviour change, 98 women became infected during the CAPRISA trial - 38 in the tenofovir arm and 60 in the placebo arm - and there was some debate at the meeting in Johannesburg about whether it was ethical for women participating in future microbicide trials to be given a placebo, now that there was evidence of an effective product.

Rees reminded the meeting that the CAPRISA findings still had to be replicated by a confirmatory trial. "If we see that a product is very effective, we can stop the study early," she said.

In the meantime, researchers and activists will have plenty of work to do, conducting studies and exploring how a microbicide product might best be manufactured, branded and distributed as cheaply as possible.