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12-03-2013 | Internal medicine | Article

Daily HIV prevention strategies not effective in African women


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medwireNews: Results of the VOICE study show that daily use of oral tablets or vaginal gel are ineffective strategies for preventing HIV in young, unmarried African women.

Adherence to the three products tested in the study - oral tenofovir, oral tenofovir/emtricitabine, and 1% vaginal tenofovir gel - was low, and none of the three products proved to be effective among the women enrolled in the study, the researchers report.

They therefore suggest that products that are long acting and require minimal daily adherence may be more suitable for this population. The VOICE (Vaginal and Oral Interventions to Control the Epidemic) findings were presented at the 20th Conference of Retroviruses and Opportunistic Infections in Atlanta, Georgia, USA.

A total of 5029 women (mean age 25.3 years, 79% unmarried) were randomly assigned to use one of the three products. HIV testing was done monthly and plasma tenofovir levels measured quarterly.

Overall, 312 (5.7%) of the women acquired HIV during the study.

After a mean follow-up period of 5511 person-years, the researchers found that none of the three products were effective in preventing HIV, and that most of the women did not use them daily as recommended.

Indeed, in an analysis of blood samples from a subset of 773 participants (including 185 women who acquired HIV), tenofovir was only detected in 28% of the women assigned to oral tenofovir, 29% assigned to oral tenofovir/emtricitabine, and 22% assigned to vaginal tenofovir gel.

HIV incidence was 8.8% for unmarried women younger than 25 years of age compared with 0.8% for older women who were married. These differences were statistically significant. Moreover, these high-risk, young, single women were much less likely to use their assigned study product than their older counterparts.

"Although there may be other explanations for why these products don't always work to prevent HIV, it's hard to ignore the fact that so few women in our study used them," said study author Jeanne Marrazzo (University of Washington, Seattle, USA) in a press statement.

"No intervention is going to be effective if it's not used, and the point is that the majority of women in VOICE didn't use any of the study products as recommended," added co-author Zvavahera Chirenje (University of Zimbabwe, Harare). "So, while we are disappointed in these results, we have answered the questions VOICE was designed to answer, and what we have learned is critically important."

The researchers conclude that an understanding of HIV risk perception and biomedical, social, and cultural determinants of adherence in this high-risk population is urgently needed.

By Nikki Withers, medwireNews Reporter

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