Paris: People with HIV reduced the risk of handing on the AIDS virus by an astonishing 92 percent while they were taking antiretroviral drugs, according to a trial reported on Wednesday.
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
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
"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 commonest
strain of the AIDS virus.
The benchmark could be when an individual has a low
count of CD4 cells and high numbers of viruses in the blood,
it suggests. The biggest impact could be among people whose
CD4 count is lower than 200 cells per microlitre, if the
research is a guide.
ART cuts down the amount of virus in blood and body
fluids such as semen and vaginal mucus 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 counselling is essential.