New technology debuted at the American Association of Pharmaceutical Scientists’ annual meeting last week will combine contraception and disease prevention into a vaginal ring. The small, flexible piece of plastic would be inserted high up in the vagina and could be left in place for 90 days. It would release both levonorgestrel, a hormonal contraceptive, and tenofovir, an antiretroviral that has been shown to inhibit the replication of HIV and herpes simplex virus-2 (HSV-2), one of the two strains of the virus that causes genital infections.

There is already a vaginal ring, called NuvaRing, on the market that can prevent pregnancy. Women insert the ring into their vagina and wear it continually for three weeks. They then remove it for one week, during which time they menstruate, and put a new ring in to start the cycle again. Similar to all hormonal methods of contraception, NuvaRing releases a combination of estrogen and progesterone to inhibit ovulation. NuvaRing does not provide any protection from sexually transmitted diseases.

Tenofovir is the first microbicide that has been proven to be effective in humans. In clinical trials, women who used a tenofovir gel before and after sex reduced their risk of HIV infection by 39 to 54 percent. The gel also reduced HSV-2 transmission by 51 percent.

The combination ring has thus far only been tested in animals but is moving into the human trial phase and has potential to be an important new tool for women. Women are more susceptible than men to both HIV and HSV-2 transmission during penile-vaginal sex, and researchers have been trying to develop products that women can control and use without needing their partner’s help or even consent. If it proves to be effective, this ring could be that method.

In addition to the combination ring, the drug company is also developing a tenofovir-only ring, and a one-size diaphragm (which will fit most women) that can be used with the tenofovir gel.

As it is just entering the trial phase, these products will not hit pharmacies for quite a while. In the meantime, it is important for both women and men to remember that currently only condoms can provide protection against both pregnancy and sexually transmitted diseases.