Scientists were extremely joyous last year when they realized a daily combination on anti-HIV pill Truvada, which is designed to treat the disease, may actually be able to prevent HIV infection.

The study’s investigators halted one arm of the trial when they noticed the Truvada did nothing to lower the risk of HIV infection in women. However Dr Fauci, director of the National Institute of Allergy and Infectious Diseases, says it’s still too early in the testing phases to draw any conclusions.

He states there could also be a biological explanation of why the protective effect found among gay men was not seen in women. There could be a physiological difference in how men and women acquire HIV since different tissues are involved during sexual contact.

Alternatively, it may be that different tissues retain different concentrations of HIV-fighting drugs, which could help explain why the medications may work in blocking infection among men but not in women.

Researchers say this discovery will lead to further studies among women to determine if there is a fundamental difference between men and women that prevents women protection from Truvada.

By J.L. Murray