Two large-scale studies in Africa are revealing an inexpensive and convenient device, coated with an antiretroviral dapivirine and replaced every month, can provide women with limited protection against the HIV virus, according to the Washington Post.

The device, a flexible vaginal ring, similar to one used for many years for birth control, can be inserted by the women themselves, and sits near the cervix while delivering a timed release of  the drug.  Researchers say the findings of the studies show great promise, even if the results were somewhat lower than the scientist expected.

One of the studies involved 2,269 women, aged 18 to 45 and living in Malawi, South Africa, Uganda and Zimbabwe.  The second study was done on 1,959 women of the same age group in South Africa and Uganda.  The findings of the studies show that use of the device led to a lower risk of transmission of the virus by 27 percent in the first study, and 31 percent in the second.  The researchers say the numbers could have been lower because of a failure of the women to adhere to the therapy.  They believe some of the participants might have only used the ring a few times per month and some, possibly, only a few hours before they came to the clinic for evaluation.

Surprisingly, the device seemed to work better in older women than in younger.  One of the groups of women aged and older, had a 56 percent lower risk of infection, and that led researchers to surmise those who failed to see a benefit to the device may have not used it correctly.

This form of treatment is not exactly a new idea.  More than 20 years ago, a number of gels, foams and rings were tested as a HIV prevention tool, but most of them did not appear to have any success.  The hope for this new trial is that the vaginal rings will be so much more convenient and inexpensive to use, more women will take advantage of them and slow the rise of HIV infections.  Reports say the device will cost around $5 and can be worn for a month, and has a shelf life of up to five years.

Findings from the first study were published in the New England Journal of Medicine, and the results of the second will be presented later this week at the Conference on Retroviruses and Opportunistic Infections.