A new gel can block the Aids virus and halve a woman’s chances of getting HIV from an infected partner, US scientists have claimed.
The breakthrough in the long quest for a tool to help women whose partners will not use condoms was reported in a study in South Africa.
The results need to be confirmed in another study, and that level of protection is probably not enough to win approval of the microbicide gel in countries like the United States, researchers say. But they are optimistic it can be improved.
“We are giving hope to women” who account for most new HIV infections, said Michel Sidibe, executive director of the World Health Organization’s UNAids programme.
A gel could “help us break the trajectory of the Aids epidemic”, he said.
Dr Anthony Fauci of the US National Institutes of Health said: “It’s the first time we’ve ever seen any microbicide give a positive result” that scientists agree is true evidence of protection.
The vaginal gel, spiked with the Aids drug tenofovir, cut the risk of HIV infection by 50 per cent after one year of use and 39 per cent after two and a half years, compared with a gel that contained no medicine.
To be licensed in the United States, a gel or cream to prevent HIV infection may need to be at least 80 per cent effective, Dr Fauci said. That might be achieved by adding more tenofovir or getting women to use it more consistently.
In the study, women used the gel only 60 per cent of the time; those who used it more often had higher rates of protection. The gel also cut in half the chances of getting HSV-2, the virus that causes genital herpes. That is important because other sexually-transmitted diseases raise the risk of catching HIV.
Even partial protection is a huge victory that could be a boon not just in poor countries but for couples anywhere when one partner has HIV and the other does not, said Dr Salim Abdool Karim, the South African researcher who led the study.
In the United States, nearly a third of new infections each year were among heterosexuals, he noted.
Countries may come to different decisions about whether a gel that offers this amount of protection should be licensed. In South Africa, where one in three girls is infected with HIV by the age of 20, this gel could prevent 1.3 million infections and 826,000 deaths over the next two decades, he said.
Dr Karim will present results of the study today at the International Aids Conference in Vienna, Austria. The research was published online yesterday by the US journal Science.
It is the second big advance in less than a year on the prevention front. Last year scientists reported that an experimental vaccine cut the risk of HIV infection by about 30 per cent. Research is under way to try to improve it.
If further study shows the gel to be safe and effective, WHO would work to speed up access to it, director-general Dr Margaret Chan said.
But the gel is in limited supply - it is not a commercial product and was made for this and another continuing study from drugs donated by California-based Gilead Sciences, which sells tenofovir in pill form as Viread.
If further study proves the gel effective, a full-scale production system would need to be geared up to make it.
PA