Thirty-three years since human-immuno virus (HIV) was discovered, the cure has proved elusive. The amount of resources spent in the search for the HIV/Aids treatment in those 33 years could probably outweigh the entire budget of Africa in the same period. 

But these have been with varied results, with cases of patients being cured of the deadly virus.

The latest in a series of research findings is that US researchers have developed a new vaginal gel that might help protect women from HIV even it is applied three hours after sex.

The significant finding, last week, comes at almost the same time as other scientists proved that some woman-to-woman sex, hitherto believed to be safe from HIV transmission, has caused infections among some of the lesbian couples.

But it is the vaginal gels for the focus here. According to the researchers, the gels containing antiretroviral drugs are important for HIV prevention but are all designed to be applied by women before sex, which can interfere with sex practices and limit their use, the researchers wrote in their Science Translational Medicine paper.

They believed a gel that can be applied after sex would be more practical because it will give women more control and would require less preparation before sex and less partner acceptance.

The gel, developed by researchers of the US Centres for Disease Control and Prevention, contains the anti-HIV drug raltegravir.

Using a macaque model to assess efficacy, the researchers found applying the gel 30 minutes before exposure protected two of three macaques from SHIV, a combination of HIV and a related monkey virus.

More importantly, the gel was equally effective when applied after exposure. The researchers said five of six macaques treated with the gel three hours after SHIV exposure remained uninfected after 20 virus challenges and the 10-week follow-up period.

The researchers noted these observations require confirmation in larger numbers of animals.

"In conclusion, we show preclinical in vivo data that support the use of topical integrase inhibitors for HIV prevention,” they said.

"This study supports evaluation of this class of drug for HIV prevention ... (and) further evaluation of postcoital modalities in women for enhanced acceptability and compliance.

The new development comes 18 years after post-exposure prophylaxis (disease prevention) was started. Post-exposure prophylaxis (or Pep) means taking antiretroviral medications as soon as possible after exposure to HIV, so that the exposure will not result in HIV infection, usually within 72 hours of exposure on a combination of ARVs as may be prescribed by a doctor.

Pep has been standard procedure since 1996 for healthcare workers exposed to HIV, but in 2005, the Centres for Disease Control allowed the treatment to be available for use after HIV exposures that are not work-related. People can be exposed to HIV during unsafe sexual activity, when a condom breaks during sex, or if they share needles for injecting drugs. Infants can be exposed from breast milk.