The Times Editorial: In a significant advance in the fight against HIV, South African researchers have pioneered the development of a gel that, in clinical trials, dramatically reduced the rate of HIV infection in women.

The trial, by the Centre for the Aids Programme of Research in South Africa (Caprisa), tested the efficacy of the gel, which contains the Aids drug tenofovir, on almost 900 women attending KwaZulu-Natal clinics.

The researchers found that the use of the vaginal microbicide reduced HIV infection in women by 39% over the two-and-a -half year test period. This follows years of disappointing results in other microbicide trials.

The Caprisa results are preliminary and must be confirmed by a second study - but they suggest that, for the first time, it might be possible to slow the rate of HIV infection by giving women another way in which to protect themselves. This is hugely important in Africa, where many women do not have the option of using condoms.

We should take pride in the fact that the study was funded by our government (supported by USAids) and was led by South African researchers: Caprisa's director, Dr Salim Abdool Karim, and his wife, Dr Quarraisha Abdool Karim, the centre's associate scientific director.

Aids activists have pointed out that the gel should not be regarded as a magic bullet and that condoms remain the most effective means of combating the spread of HIV.

For scientific and commercial reasons, it will probably take years for the gel to become available. But the signs are encouraging.

According to The New York Times, Gilead Sciences, the California company that developed tenofovir, donated 100kg of the drug's active ingredient for the study. And it has agreed to forego royalties on the gel if it is ultimately distributed in Africa and poor countries elsewhere.