People with HIV reduced the risk of passing on the AIDS virus by an astonishing 92 percent while they were taking antiretroviral drugs, according to a trial reported on Thursday.
The research provides the strongest evidence to date that drugs which treat the human immunodeficiency virus could also be incorporated into strategies for fighting HIV's spread.
In a paper published by the British journal The Lancet, doctors recruited 3,381 heterosexual couples in seven African countries.
Each couple was "serodiscordant," meaning that one of the pair was infected with HIV while the other was uninfected.
Antiretroviral drugs were given to 349 individuals after their immune system, as measured by the numbers of CD4 cells, plunged below a given threshold. The other infected individuals received a dummy pill called a placebo.
The researchers took blood samples from the other partner every three months to see whether he or she had become infected. The trial was closely monitored by an ethics committee, and included a training course in safe sex as well as routine health checkups.
After 24 months, 103 partners who had been HIV-free at the start of the experiment had become infected with the virus by their partner.
But only one of these 103 transmissions was caused by a partner who was on antiretrovirals.
The results were confirmed by genetic fingerprinting of the virus, showing whether it had been passed on by an infected partner or by someone from outside the trial.
All in all, taking antiretroviral therapy (ART) reduced the risk of infecting someone else by 92 percent, a whopping fall that highlights the potential of these drugs as a weapon to prevent HIV, rather than just treat it, say the authors.
"Provision of ART to HIV-1 infected patients could be an effective strategy to achieve population-level reductions in HIV-1 transmission," says the paper.
HIV-1 is the most common strain of the AIDS virus.
ART cuts down the amount of virus in blood and body fluids and so reduces exposure to a non-infected person, experts believe.
There is a caveat, though, say the authors. Even though ART may lower the risk of infecting others, the danger is not eliminated, so safe-sex counseling is essential.
Copyright AFP
