For biological, social and economic reasons, women are more vulnerable than men to HIV/Aids infection. So the search for a female- controlled method of preventing the transmission of HIV grows ever more pertinent.
The disappointing progress in the development of an HIV vaccine has cast new light on research into an effective microbicide — a gel inserted into the vagina before sex to prevent HIV transmission.
But the rekindled interest also relates to the steady, if slow, advances in recent years in developing a safe and effective microbicide. Compared with vaccine trials, which are not in phase three anywhere (except for a controversial study in Thailand), microbicide phase three trials are starting in several places around the world. South Africa has the largest number of women participants and the widest spread of products are being tested here.
Drug companies have shown little interest in microbicides, which has hampered research efforts. The big pharmaceuticals see little profit potential in a preventative product targeted mainly at poor women in developing countries — a product that must retail cheaply for any chance of success. Currently all microbicide research is funded by governments and donor agencies.
But now, with researchers expressing cautious optimism about several microbicide products, there are hopes that a gel that reduces — if not prevents — transmission rates by as much as 60% could be on the market by 2007. As with most microbicides under the microscope, these two products are entry inhibitors — they prevent the virus from attaching to its target cells.
For the past two years, the Reproductive Health Research Unit (RHRU) has been working on a feasibility study with the Microbicides Development Programme and the Medical Research Council UK in London.
“We hope to be the first off the block,” says Jocelyn Moyes, director of microbicide research at the unit. The RHRU is running a two-month pilot in preparation for the big one — set to involve 3 000 women in Soweto and Orange Farm over three years . All women in the study will be encouraged to use condoms — it would be unethical, if scientifically less complicated, not to do so. But because regular condom use is thought to be so low, in part because of women’s inability to compel their partners to use them, the large-scale study is expected to show results — whether condoms are used or not.
There were fears at first that the participants would baulk at the mandatory HIV test. (They must, of course, be HIV-negative). But, says Moyes: “We haven’t had a problem. Women seem to want to know their status. Perhaps they see it as taking some sort of control.”
Although the ideal is for male partners to be involved in matters of sexual health, this is not always possible for the millions of women unable to negotiate safe sex. Researchers are keen to create a product that can be used undetected and that comes with or without a spermicidal contraceptive.
While phase one and two trials are all about safety, phase three trials are about efficacy. In essence, will the product work? Only time will tell, but as Moyes points out, pointers towards efficacy in preliminary trials must already be established before research moves into the final stages.
As to whether microbicides could really slow the spread of the epidemic, figures produced by the London School of Hygiene and Tropical Medicine are frequently trotted out: a 60% effective microbicide could prevent 2,5-million infections if used by 20% of women in 73 developing countries over three years, according to one model. Researchers say that by 2012, between 70% and 90% effective second-generation microbicides that could also stop the spread of other sexually transmitted diseases, could be on the market.
Some sceptics scoff at these figures as “spin” and argue that some of the millions of dollars being poured into expensive research with shaky outcomes should be diverted instead into saving lives. They also express doubts over whether women will use a product that is only 60% effective.
Gita Ramjee, director of HIV Prevention Research Unit at the Medical Research Council in Durban, disagrees.
“People fail to realise how desperate women are. They will use a product that is only 20% effective. There are not many women out there who can negotiate safe sex,” she says.
According to Moyes, the biggest problem is the lack of uptake by the pharmaceutical industry.
“It won’t be a money-spinner, so it’s hard to get a drug company to make and market it,” she says.
But if and when this happens, microbicides could well become an effective, woman-controlled weapon against HIV.
Philippa Garson is a fellow in the HIV/Aids and the Media Project, run by the Perinatal HIV Research Unit and the journalism programme at the University of the Witwatersrand