Magazine article UN Chronicle

Microbicides New Hope for HIV Prevention

Magazine article UN Chronicle

Microbicides New Hope for HIV Prevention

Article excerpt


HIV/AIDS is particularly severe in Africa, where women bear a disproportionate burden of the epidemic. One of the most crucial challenges in HIV prevention in Africa is to reduce the high infection rates among young women. Worldwide, just over half of all people living with HIV are women, and 70-90 per cent of all HIV infections among women are through heterosexual intercourse. (1) In sub-Saharan Africa, women aged fifteen- to twenty-four years with HIV represent 76 per cent of the total cases in that age group, outnumbering their male peers by as much as eight to one. (1) Although the majority of new HIV cases in the United States are through male-to-male sexual contact, heterosexual contact accounts for 84 per cent of new infections among women.


Women have few options to reduce their risk of acquiring HIV infection. They are often unable to convince their male partners, especially husbands and regular partners, to be monogamous and/or to use condoms. New technologies to enable women to protect themselves from sexual transmission of HIV are urgently needed. One of those is topical microbicides--products designed to prevent HIV and other sexually transmitted infections. (2-4) They can potentially be applied vaginally or rectally and, importantly, they are unique as being a female-controlled option.


After several years of disappointing microbicide trials that were unable to show protection against HIV infection, (5-10) or were even potentially harmful, (11-13) the results of the Centre for the AIDS Programme of Research in South Africa (CAPRISA) 004 tenofovir gel trial, released in July 2010, finally provided the evidence that the antiretroviral drug, tenofovir gel, used before and after sex can prevent HIV infection in women. (14) This landmark study has been heralded as one of the most significant scientific breakthroughs in the fight against HIV/ AIDS with global health leaders calling the results "a game changer," "a true breakthrough for AIDS prevention," and "a significant milestone for women in the thirty year history of the HIV/AIDS epidemic"

The CAPRISA 004 trial was a double-blind, randomized, placebo-controlled trial including 889 rural and urban South African women, aged eighteen to forty years, who were sexually active and HIV-negative. A total of 445 randomly assigned women received vaginal applicators containing a 1 per cent concentration of tenofovir in a gel formulation, and 444 women received applicators filled with a placebo gel that looked identical to the study gel but did not contain tenofovir. Study participants, who received HIV risk-reduction counseling, condoms, and monthly examinations, were told to apply no more than two gel doses in twenty-four hours: the first dose anytime within twelve hours before sex, and a second dose as soon as possible within twelve hours after sex.

The HIV incidence in the tenofovir gel arm was 5.6 per 100 women-years, compared to 9.1 per 100 women-years in the placebo gel arm. Tenofovir gel reduced HIV acquisition by 39 per cent overall, and the protective effect of tenofovir gel against HIV infection reached 54 per cent in women who used the gel consistently.

Tenofovir gel was also shown to be 51 per cent effective in preventing herpes simplex type 2 virus. (15) Genital herpes infection is an incurable lifelong condition, which potentiates the spread of HIV infection. Tenofovir gel is the first medical technology shown to prevent genital herpes, which is one of the most common sexually transmitted diseases globally.


CAPRISA 004 provided the proof-of-concept evidence that an antiretroviral drug can prevent sexual transmission of HIV in women. In addition to being the first study to demonstrate the effectiveness of a vaginal microbicide for the prevention of HIV, the CAPRISA 004 trial was the first microbicide trial where the consortium of partners was led by a developing country institution: the Centre for the AIDS Programme of Research in South Africa (CAPRISA), based at the University of KwaZulu-Natal in Durban, South Africa. …

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