Half of the 33 million people living with HIV worldwide are women. In South Africa, which accounts for 70 per cent of the global HIV burden, about one in three women in the 20-34 age group is estimated to be infected. Large numbers of women in countries like India get infected despite their being in monogamous relationships. Hence the scientific community has had a strong sense of urgency in its quest for a safe and effective gel (microbicide) that women can use for self-protection. Now there is promise of a safe and effective microbiocide, going by the results of a clinical trial carried out on nearly 900 women in South Africa and published online in Science (“Effectiveness and safety of tenofovir gel, an antiretroviral microbiocide, for the prevention of HIV infection in women,” by Quarraisha Abdool Karim et al.) The gel, which can be topically applied to the vagina, was tried out in two sites in KwaZulu-Natal province — the epicentre of HIV in South Africa — from May 2007 to December 2009. Where the clinical study found an average protection of 39 per cent, protection levels shot up to 54 per cent in the case of women who used it more than 80 per cent of the time. The positive outcome caps nearly 20 years of research and trials of six microbiocides. Unlike other microbiocides, which even increased the chances of HIV infection, the one tested in KwaZulu-Natal province contained one per cent of tenofovir, an antiretroviral drug that is currently used as tablets in many countries to treat HIV.

More trials involving many volunteers are needed to corroborate the results of the latest trial. A microbiocide with tenofovir (MTN 003) is already on trial in South Africa since September 2009, and the process is expected to be completed in 2014. Unlike the current trial, MTN 003 will enrol a larger number of volunteers — 5,000. Though only a minimal amount of tenofovir is being used, this and the future trials need to look for resistance to the antiretroviral drug. Another challenge is to improve compliance. The KwaZulu-Natal trial required women to use the gel twice — first less than 12 hours before sex and again within 12 hours after sex. It was felt that to ensure adherence to such a specific dosage might be difficult. Indeed, the adherence rate was found to be less than 50 per cent in as many as 367 of the nearly 900 women. The MTN 003 trial will have a daily dosage schedule. It is hoped the results of this trial will bring more clarity in respect of the dosage schedule, the levels of adherence, convenience, and the protection achieved.

Correction and Clarification

The gel used in the prevention of HIV infection in women is a microbicide. It was misspelt as microbiocide in the heading and the text of “Promising microbiocide”

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