Scientists on Monday reported failure in a large African trial of three different ways to protect women against H.I.V.
The failure was due not to the methods - two different pills and a vaginal gel - but to the fact that the women did not use them consistently.
Adherence among the women in the study was “very low,” a researcher from the University of Washington said at the Conference on Retroviruses and Opportunistic Infections in Atlanta, where the results were presented.
Because other studies have shown that the pills and gel can be protective when used, some AIDS experts urged that more studies be done and that donors not back away from the idea of “pre-exposure prophylaxis.”
The study, known as Voice, for Vaginal and Oral Interventions to Control the Epidemic, followed more than 5,000 women in South Africa, Uganda and Zimbabwe. Some were given daily pills to take containing the antiretroviral drug tenofovir, some got pills with Truvada (tenofovir and a booster drug), and some got a tenofovir-containing vaginal gel.
Although 95 percent of the women in the study made their monthly clinic visits, and 70 percent said they were using the pills or gel, blood tests suggested that only 25 percent actually were.
Although the study did not explain why adherence was so poor, Mitchell Warren, the director of AVAC, an AIDS prevention advocacy group, said that apparently “these women just had the sense that ‘H.I.V. won’t happen to me.’ ”
That was consistent, he said, with results from a recent study in which young gay American men were given Truvada for protection. The men stuck with the study and enjoyed being interviewed monthly, but they did not take their pills every day, even if they told researchers they did.
Young people think they are invulnerable, Mr. Warren said, and pre-exposure prophylaxis may not work until slow-release products that provide protection for months are available.
Such products are undergoing animal testing now.