Found at http://www.newscientist.com
18:26 13 May 2011 by Andy Coghlan
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In a decisive breakthrough against the spread of HIV, an international study has demonstrated conclusively that antiretroviral therapy blocks the spread of HIV from an infected person to their uninfected partner.
The study, which was halted early because the results were so compelling, covered 13 countries and involved 1763 “discordant” couples, in which one partner carried the infection at the outset.
In 886 of the couples, the infected partner received antiretroviral drug therapy (ART) straight away, while treatment was delayed in the other 877 couples until the infected partner showed pre-defined signs of sickness.
Preliminary results, announced yesterday by the US National Institute of Allergy and Infectious Diseases (NIAID), showed that only one of the 886 individuals who received immediate treatment passed the virus to their partner. There were 27 cases of cross-infection in the 877 couples where treatment was delayed.
Faced with this 96 per cent reduction in risk, the study was halted between three and four years early so all of the couples could be treated.
“This new finding convincingly demonstrates that treating the infected individual, and doing so sooner rather than later, can have a major impact on reducing HIV transmission,” says Anthony Fauci, director of NIAID.
“This is a crucial development, because we know that sexual transmission accounts for about 80 per cent of all new infections,” says Margaret Chan, director-general of the World Health Organization.
Called HPTN 052, the trial was led by Myron Cohen of the University of North Carolina at Chapel Hill. The results show that the treatment blocked transmission from either male or female partners, as there were equal numbers of both in the trial. Few gay couples were involved – just 3 per cent of those participating – so no knows yet whether the treatment would be equally effective for them.
All couples were counseled to continue their usual safe-sex practices, including use of condoms, to exclude this factor as a potential difference between the two groups.
To qualify for the trial, infected participants had to be at a relatively early stage of infection where CD4+ cells – the white blood cells targeted and depleted by HIV – were still moderately high, with counts of between 350 and 550 per millilitre of blood.
Current aid programs aimed at spreading treatment to all developing countries typically wouldn’t treat patients with CD4 counts this high. The count needs to fall below 350 before treatment begins – a strategy introduced by the WHO in 2009. But Cohen and his colleagues wanted to evaluate the potential for giving the drugs preventively in relatively healthy individuals, to see if it would help them avoid infecting their partners.
In the wake of the trial, the WHO will be under pressure to allow infected people with counts between 350 and 500 to qualify for treatment as part of a program specifically aimed at preventing infection of partners.
The WHO will issue its new guidelines in July, and Chan said yesterday that “the findings from this study will further strengthen and support the new guidance that WHO is releasing in July to help people living with HIV protect their partners”.
“We very strongly feel that treatment for prevention in this group must be an option they can choose,” says Bernhard Schwartlander, director of evidence, strategy and results at UNAIDS.
“We know that ART very effectively suppresses the multiplication and level of virus in blood and mucosal cells, such as those lining the vagina, and we’ve already successfully applied this same principle for years in treatment to block mother-to-child transmission of HIV,” says Schwartlander. “So if the prevention option is included in the guidelines in July, I think it would be a major step forward,” he says.
The trial is the second this week to provide new hope against HIV, which has so far killed 30 million people with 33 million infections around the world. Earlier this week, a vaccine trial in monkeys produced the first conclusive evidence that a vaccine could completely suppress the virus, but it could take a decade to demonstrate whether the approach works in people.