Trying to prevent HIV infection through vaginal gels or daily tablets has proven ineffective in the southern African region ravaged by the disease because people did not use the medicines properly, a study released on Monday said.
A ground-breaking study issued in 2010 indicated a vaginal gel containing an HIV drug can sharply reduce infections in women who use it before and after sex.
However, a test of the gel and two types of anti-HIV pills among more than 5,000 women in South Africa, Zimbabwe and Uganda showed that, based on blood tests, more than 70 percent did not use the medication as instructed.
"We are obviously disappointed in the results. We were very hopeful that these products, which we know have been effective in other studies and clearly have a lot of promise, would work," Jeanne Marrazzo, a researcher on the project for the University of Washington, told reporters in a teleconference.
"Women did not use consistently any of the products. Adherence was very low," said Marrazzo, part of the project known as the Vaginal and Oral Interventions to Control the Epidemic (VOICE).
HIV/AIDS experts said the results showed how important a factor human behavior is when devising ways to prevent HIV.
"HIV prevention is never just biomedical - behavior is key. What we've learned from VOICE and other trials is that adherence to the prescribed dose - the behavioral component - is the variable that determines effectiveness," said Mitchell Warren, director of the HIV prevention advocacy group AVAC.
East and southern Africa are the areas most heavily affected by the HIV epidemic. Out of the total number of people worldwide in 2009 living with HIV, 34 percent were in 10 countries of southern Africa, according to the U.N. Programme on HIV/AIDS.
Experts have been searching for years for inexpensive, safe and simple medications to decrease the risk of transmission among a population that is largely destitute and with little access to quality health care.
The study also found the group most likely to contract HIV - unmarried women under 25 - was also the most likely not to use any of the medicines. The results were presented at a Conference on Retroviruses and Opportunistic Infections in Atlanta.
The three-year study that started in September 2009 tested a daily tablet called Truvada, which was approved for HIV prevention in July 2012 by the U.S. Food and Drug Administration after it was shown to significantly reduce the risk of HIV infection when used as a preventative measure.
The gel with a drug called tenofovir, which a previous study showed reduced HIV infections in women by 39 percent over two and a half years, and an oral tenofovir tablet were also tested.
Researchers have been trying for years to formulate a microbicide - a gel, cream, ring or tablet inserted into the vagina or rectum before sex to prevent transmission of the human immunodeficiency virus (HIV) that causes AIDS.
"We need to rethink the design of these intervention trials ... in healthy people because it is difficult for anybody to take a pill or anything every day, particularly when you are healthy and do not feel that you need a drug," said Marrazzo.
Truvada is made by Gilead Sciences, which also developed tenofovir. In 2006, Gilead assigned a royalty-free license for tenofovir gel to CONRAD.
Jonathan Mermin, an HIV/AIDS prevention expert at the U.S. Centers for Disease Control and Prevention (CDC) said these trial results underscored the complexities of getting healthy people to use preventative measures against HIV.
"Clinicians and public health professionals will have to further assess and better understand how to promote and support the high levels of adherence necessary," he said.