Durban - The much anticipated pill-a-day HIV prevention tool has been dealt a huge blow: a large-scale study – mostly conducted in South Africa – has found that most women do not take the one antiretroviral drug daily.
Widely know as the Voice (Vaginal and Oral Interventions to Control the Epidemic) trial, it tested whether ARV pills tenofovir, Truvada (a combination of tenofovir and emtricitabine) or a tenofovir gel (a vaginal microbicide) were safe and could prevent sexual transmission of HIV.
The 5 029 female participants were given one of these prevention methods, depending on which study arm they were in.
One of the lead investigators, Dr Jeanne Marrazzo, of the University of Washington in Seattle, confirmed on Monday that their results showed that daily use of the pills or microbicide was neither effective nor acceptable to the participants.
The unmarried, under-25-year-old women were found to be the least likely to adhere to the daily dosage, with the HIV incidence remaining very high, especially in areas of high prevalence such as KwaZulu-Natal.
“Adherence was a critical determinant of effectiveness and we knew poor adherence would affect the study results,” said Marrazzo.
She and her co-investigator, Dr Mike Chirenje, of the University of Zimbabwe, were due to present their results at the 20th Conference on Retroviruses and Opportunistic Infections in Atlanta on Monday.
Marrazzo said that although the results were disappointing, Voice had provided a clear answer – that daily use of the product, whether a vaginal gel or oral tablet – was not the right HIV prevention approach for African women like those in the study, who were predominantly young, unmarried and known to be at high risk.
She also said that the high HIV incidence among the South African trial participants – seven percent, compared to 0.8 percent in Zimbabwe and 2.1 percent in Uganda – could be ascribed to the fact that they had managed to enrol women who were at high risk.
HIV incidence reflected the number of women who became newly infected for every 100 participants in a given year. It was nearly 10 percent at some South African trial sites.
Truvada has been found to be effective in other trials in other populations, and was subsequently approved by the US Food and Drug Administration for HIV prevention.
In July 2010, the Caprisa 004 study in South Africa found that tenofovir gel was safe and reduced the risk of HIV by 39 percent among women who used it before and after sex, but the study was small and further study was required.
In the Voice trial, the women used the gel once a day, but not necessarily when there was sexual intercourse. – Health-e News