Providing healthy people with an antiretroviral drug to protect them against HIV infection could drastically slow the spread of the virus in sub-Saharan Africa, US researchers said Tuesday.
In a best-case scenario, the drug could prevent three million new HIV cases in this part of Africa over a 10-year span, even if it was only made available to the most sexually active individuals, the investigators said.
"This could represent another tool in our arsenal against HIV
infection," said Ume Abbas, an assistant professor of medicine at the
University of Pittsburgh School of Medicine and lead author of the
The drug in question is tenofovir, one of the cocktail of antiretroviral medications given to HIV patients.
Very effective in monkeys
In studies on monkeys, the drug has been shown to be very effective in protecting them against the simian version of the human immunodeficiency virus that can lead to Aids, and it is now being tested in humans.
US health authorities are funding five separate trials involving
high risk groups such as gay and bisexual men, sex workers and
intravenous drug users, on four continents.
The earliest results of those trials will not be available until
early 2008, but US and British researchers decided to use computer
modelling to project ahead to evaluate just how useful the drug
treatment might be in reducing HIV transmission rates in the context of
the HIV/AIDS epidemic of southern sub-Saharan Africa if and when it is
approved for that purpose.
The researchers looked at three different scenarios. In the first
they assumed that the drug was effective 90 percent of the time, and
that 75 percent of the sexually active population (15-49 year-olds)
could be persuaded to pop a daily pill to protect themselves from HIV.
May cut new infections by 74 %
If that rosy scenario panned out, the strategy could potentially cut
new HIV infections by a whopping 74 percent over a decade, according to
the computer projections.
If the drug was only effective 60 percent of the time and used by
just 50 percent of the sexually active population, the reduction fell
to about 25 percent over the same time period.
Finally, the researchers modelled a scenario where the drug was
effective 30 percent of the time and only a quarter of the target
population used it, yielding a reduction in new cases of a mere 3.3
Even assuming that the drug does prove as effective in humans as it
was in monkeys in protecting healthy individuals from infection, it is
"never going to be feasible to treat the entire population," Abbas
But even if governments or aid agencies were able to find the funds
to supply the drug to the most sexually active individuals - an
estimated 18 percent of the population - it could still make a big
dent in the problem, slashing the infection rate by almost 30 percent
over a decade.
3.2 million cases
That translates to 3.2 million cases.
"Our data highlights the enormous potential public health benefit of
pre-exposure chemoprophylaxis against HIV, provided the regimen is
efficacious and used consistently daily for a number of years," said
John Mellors, a professor at the University of Pittsburgh.
Sub-Saharan Africa is the epicentre of the global HIV/Aids epidemic,
with more than 22 million adults infected with the virus.
The study appears in PLoS One, a journal of the Public Library of
Science. – (Sapa-AFP)