The success of a new anti-HIV gel in trials has been hailed as a “major advancement” by one of the world’s leading experts, Professor Robin Shattock of St George’s, University of London.

The new microbicide gel was found to halve women’s chances of getting HIV from an infected partner.

If the results from the South African trial are confirmed in a follow-up study, this will be the first time a microbicide gel has proven to be effective in preventing the disease spreading.

Prof Shattock, professor of molecular infection at St George’s, said. “This is the first biological intervention that has had a clear-cut impact on HIV transmission. The study represents a major advancement for HIV prevention research and provides an important new approach to reducing HIV infections.

“This is good news for South Africa, set against a background where young women in the developing world continue to bear a disproportionate number of new HIV infections. This was a trial performed by South African researchers for South Africans, which makes it all the more impressive. It is likely to have a far more enduring legacy than that of staging the World Cup.”

The vaginally applied microbicide gel, which contained the AIDS drug tenofovir, reduced the rate of infection by 50 per cent after one year, and 39 per cent after two-and-a-half years. It also reduced by 50 per cent the chance of catching the common sexually transmitted infection genital herpes, which itself increases the risk of contracting HIV.

New ways to stop the spread of HIV in trouble regions such as sub-Saharan Africa – where nearly 60 per cent of those infected are women – are needed urgently. Microbicide gels – substances intended to stop the transmission of the HIV virus when applied to the vagina or rectum before and after sex – are seen as a good defence for women whose partners refuse to wear condoms.

The latest study was conducted by the Centre for the Aids Programme of Research in South Africa (CAPRISA), and follows years of disappointing trials of microbicides by various organisations.

Prof Shattock said: “We really hope that this important finding will provide the momentum to ensure sufficient funding will be put behind the search for safe and effective microbicides. An effective microbicide would provide a discreet method that women can use to avoid sexual transmission of HIV.

“The study showed no safety concerns, which is important for a product designed to be used by healthy individuals, and its use vaginally means that the levels of drug used are 10-100 times lower than what would be needed to be used orally. While the results are extremely promising, they will need to be confirmed in additional studies before the gel can be made more widely available.”