Preventing the transmission of HIV/AIDS has been an elusive goal for researchers. But a new study published in the current issue of Science by a team from Columbia University’s Mailman School of Public Health offers a remarkable breakthrough. Notably, their approach offers the first viable way for women to actively protect themselves from HIV infection without having to persuade a partner to use a condom.
Results of the study were announced at the XVIII International AIDS Conference in Vienna, timed to coincide with the online publication of the study in Science.
The study was led by the husband-wife team of Salim S. Abdool Karim and Quarraisha Abdool Karim, both professors of clinical epidemiology at the Mailman School and director and associate director, respectively, of the Centre for AIDS Programme of Research in South Africa (CAPRISA). Their team of Columbia-trained researchers found that the use of a vaginal gel containing the antiretroviral drug tenovofir reduced a woman’s chance of becoming infected with HIV during sex by 39% compared with a control group that used a placebo gel. Earlier studies of vaginal gels to prevent HIV transmission have not been successful.
“This new technology has the potential to alter the course of the HIV epidemic, especially in southern Africa where young women bear the brunt of this devastating disease,” observed Dr. Quarraisha Abdool Karim.
“This is an advance because it empowers women,” said Dr. Salim S. Abdool Karim. “What you can advise women right now is to get the man to use condoms. We haven’t had something that a woman can control.”
The study involved 889 South African women, who were instructed to use the gel within 12 hours before sexual intercourse and again within 12 hours afterward. After 12 months, there were 50% fewer instances of HIV infection among women who used the gel compared with the placebo group.
After two and a half years, there were 39% fewer cases among those using the tenovofir gel. The degree of protection was proportional to the degree to which the women complied with the instructions. Women who reported using the gel more than 80% of the time they engaged in sexual relations had a 54% reduction in HIV infection, whereas those who used the gel less than half the time had a 28% reduction.
If the study results are supported by further studies, the researchers estimate that widespread use of the gel could prevent over half a million new HIV infections in South Africa alone over the next decade.
“For every 20 women using the gel, we’ve prevented one HIV infection,” says Dr. Salim S. Abdool Karim. “That’s a pretty good rate of return. If we implement this gel and see at a community level a similar profile of efficacy, we would prevent about 1.3 million HIV infections over 20 years in South Africa alone.”
Offering women a way to protect themselves is a critical advance and a particularly urgent need in sub-Saharan Africa where, according to U.N. estimates, about 60% of HIV cases occur in women. In Vulindlela, South Africa, a region where the gel was tested, half of pregnant women ages 24 or older are infected with HIV/AIDS. Fewer than a quarter of participants in the trial said that their partners used a condom. About a third said that their partners did not know that they were using the gel.
The study also showed that the gel was effective in preventing transmission of genital herpes simplex virus (HSV-2). The women using the tenovofir gel had 51 percent fewer cases of HSV-2 infection than the control group. Earlier research has shown that genital lesions caused by herpes virus increases vulnerability to infection with HIV/AIDS.
“Tenofovir gel has a potential dual effect in preventing HIV,” explains Dr. Salim S. Abdool Karim. “Since women with genital herpes are much more likely to become infected with HIV, the additional protection of tenofovir gel against herpes creates a second mechanism in preventing HIV.”
“The trial’s findings create a new vision for the prevention of HIV and a public health approach to controlling HIV,” added Dr. Linda Fried, dean of Columbia’s Mailman School of Public Health.
The study was jointly funded by the Governments of South Africa and the United States, through the Technology Innovation Agency (TIA) and the U.S. Agency for International Development (USAID), respectively. Tenofovir was provided free of charge by Gilead Sciences Inc. of California. The drug is widely used to treat HIV infection.
July 20, 2010