The candidate vaginal microbicide gel Carraguard does not protect women from HIV infection, reports an Article in this week's edition of The Lancet, written by Stephanie Skoler-Karpoff and Barbara Friedland, Population Council, New York, USA, and colleagues.
Around 33.2 million people worldwide are living with HIV, of whom 68% live in sub-Saharan Africa; and in that region, women and girls are disproportionately affected, accounting for 61% of infections. Furthermore, in 15-24-year-olds, 90% of new HIV infections occur in girls and women. As a result, female-initiated HIV-prevention options, such as microbicides, are urgently need. In this randomised, placebo-controlled trial, the authors assessed Carraguard, a carrageenan-based compound developed by the Population Council.
The trial took place at three sites in South Africa, and involved 6,202 sexually active, HIV-negative women, who were assigned to receive Carraguard (3103 women) or a placebo gel of methylcelluose (3099). The women were instructed to use one applicator of gel plus a condom for each vaginal sex act. Participants were followed up for up to two years. The women visited a clinic every three months, which included testing for HIV presence and pregnancy, pelvic examinations, risk reduction counseling, and treatment for curable sexually transmitted infections and symptomatic vaginal infections. The primary outcome of the trial was time to seroconversion (HIV infection).
The researchers found that HIV incidence was 3.3 per 100-woman years in the Carraguard group (134 infections) and 3.8 per 100 woman-years in the placebo group (151 infections), with no significant difference in the time to serocoversion. Rates of self-reported gel use (96.2% Carraguard, 95.9% placebo) and condom use (64.1% both groups) at last sex acts were similar in both groups. On the basis of applicator testing, however, gel was estimated to have been used in only 42.1 % of sex acts on average (41.1% Carraguard, 43.1% placebo). Adverse events were similar in both groups; adverse events related to gel use and serious adverse events were similar in both groups.
The authors conclude: "This study did not show Carraguard's efficacy in prevention of male-to-female transmission of HIV, although no safety concerns were recorded. Low levels of gel use could have compromised the potential to detect a significant protective effect. Although the results from this and other completed microbicides efficacy trials have been disappointing, the search for female-controlled HIV-prevention methods must continue."
In an accompanying Comment, Dr Willard Cates and Dr Paul Feldblum, Family Health International, North Carolina, USA, say: "Whenever we develop effective new tools for HIV prevention, no single approach to prevention will suffice. Rather a combination of partly effective prevention approaches will be bundled into packages targeted to specific populations. This bundling will involve behavioural, biomedical, and structural interventions, each designed to reinforce the effect of the other. The cumulative influence of combination prevention is our hope for thwarting the spread of HIV."
Stephanie Skoler-Karpoff , Population Council, New York, USA T) +1-917-584-7252 E) skolers@mskcc.org
Barbara Friedland, Population Council, New York, USA T) +1 212-339-0629 E) bfriedland@popcouncil.org
Dr Willard Cates, Family Health International, North Carolina, USA contact by e-mail E) Wcates@fhi.org
For full Article and Comment: http://press.thelancet.com/carraguardfinal.pdf
Journal
The Lancet