MRC president Professor Anthony Mbewu confirmed that on January 31 the US-based agency CONRAD had informed the MRC that its international clinical trial of a vaginal microbicide cellulose sulphate (Ushercell) would have to be terminated early due to concerns by the Independent Safety Monitoring Committee that the microbicide might actually be increasing HIV transmission rather than preventing it.

Mbewu said all 604 women enrolled on the trial at the MRC clinical trial site have been informed, and the ‘€œ20 or more’€ who became HIV positive during the trial have been enrolled into a programme of care.

‘€œIt is as yet uncertain whether some of these women became HIV positive as a result of use of the microbicide, and this is currently being investigated,’€ Mbewu said.

Mbewu confirmed that following a meeting with the health minister Dr Manto Tshabalala-Msimang the MRC trial site would be inspected by the National Health Research Ethics Committee.

He gave the assurance that all MRC clinical trials were conducted according to the highest ethical standards and adhered to strict clinical trial protocols.

The Treatment Action Campaign pointed out that there was  a commonly held myth about microbicide trials which needed to be dispelled.

This myth has been perpetuated by at least two senior South African politicians and we have encountered journalists who have mistakenly believed it. The myth is that participants in microbicide trials (as well as vaccine trials and the recently conducted circumcision trials) are encouraged to have unprotected sex or, in the myth’s most extreme version, exposed to HIV by researchers. This is false,” the TAC said in a statement.

“On the contrary, participants in these trials must be counselled about safer sex. If a trial is conducted properly, participants are arguably at less risk of contracting HIV than the general population, because they have all been through a standardised comprehensive counselling session, approved by a regulatory ethics committee,” the TAC said.

The search for an effective and safe anti-HIV microbicide was been dealt a blow with recent news that two Phase III trials had been halted after evidence that there was potentially an increased risk of HIV infection for women using the substance.

Two Phase III trials of Ushercell (a cellulose sulfate-based barrier vaginal gel being tested for HIV prevention in women during sex) were being conducted in South Africa, Benin, Uganda and India.

This is the second failure of a potential microbicide in a full-scale trial in recent years. In 2000, a large full-scale trial showed that the only other microbicide candidate, nonoxynol-9, was unsafe when it had been expected to be effective.

Women in that trial developed a higher incidence of HIV infection, presumably through ulcers caused by chemical irritation.

In the latest failure the findings of increased risk were identified at some sites in a trial sponsored by CONRAD, a cooperating agency of USAID administered through the Department of Obstetrics and Gynecology at Eastern Virginia Medical School in the United States.

The South African leg of the trial was being conducted in South Africa by the MRC’€™s HIV Prevention Research Unit in Durban.