A multi-national study shows that if an HIV-positive person starts taking antiretroviral therapy early on, that is, when their CD 4 count is still high, their chances of infecting their HIV-negative partner can decrease by as much as 96%.
The results of the study are viewed as confirmation of untested wisdom among clinicians who have for a number of years thought that people on combination antiretroviral therapy have a lower chance of transmitting HIV to their uninfected partners. This was presumed on the basis that ARVs fight off HIV infection, which results in the reduction of the viral load in one's system. The study involved almost 1 800 people in sero-discordant relationships, where one partner has HIV and the other doesn't. They were from Africa, Asia and the Americas. In South Africa, the study was conducted at two sites in Johannesburg - Helen Joseph and Chris Hani Baragwanath Academic hospitals, and involved almost 100 participants. A key requirement was that they needed to have a considerably higher CD 4 count of 350 - 550.
"We were looking to confirm or to evaluate whether combination antiretroviral treatment can interrupt HIV transmission between HIV-discordant partners", says Dr Guy de Bruyn, the principal investigator who conducted the clinical study at Chris Hani Bara.
The result showed a significant potential.
"We've shown that there's a 96% reduction in transmission of HIV from the positive partner to the negative partner", says Dr Sharlaal Badal-Faesen, the principal investigator at the Helen Joseph Hospital site.
This was a randomised study where participants were divided into two groups. Those on the intervention arm were given different ARV combinations and those on the control arm started receiving ARVs only when they reached a stage where, according to national AIDS treatment guidelines, they would qualify for treatment at a CD 4 count of 200 or when they started getting ill with AIDS defining symptoms.
"On the one arm, 50% of these patients received ARVs immediately. On the second arm, those patients did not receive ARVs when they started on the trial. They were monitored until their CD 4 counts reached 250 or below, and then initiated on ARVs. So, in that way we could compare subjects that got ARVs to subjects that do not get ARVs", explains Dr Badal-Faesen.
Dr de Bruyn adds that "there had been 28 infections that were linked in other words, that were demonstrated by molecular methods to have come from the HIV-infected partner and passed to the initially uninfected partner. Of those 28, 27 were in the group that received treatment according to guidelines and only one was in the group that received immediate antiretroviral therapy. So, that is where we arrived at the 96% difference comparing those two rates".
He says throughout the study, participants were advised to follow safe sexual practices, which some might have followed adequately and others not. That, then, would explain the differences in levels of infection in both study groups.
"What we are reporting is the actual number of infections that occurred. Essentially, we're showing that the immediate treatment arm was protected at a far higher rate than people that were in the arm that was treated per guidelines. We assume that the behaviours, on average, would have been similar across both groups. That's something that's inherent in a randomised trial. For example, potentially by the act of randomization, the propensity to use condoms when advised to do so should be equally distributed between the two groups", Dr de Bruyn says.
The second element of the study was to investigate whether early anti-retroviral therapy can protect HIV-positive people from HIV-associated illnesses, as "starting patients earlier on ARVs obviously improves their immunity. So, in so doing they have the added advantage of protection from opportunistic infection", adds Dr Badal-Faesen.
"In this particular study we've shown that there was a 40% reduction in morbidity", she says.
The recommendations arising out of the findings suggest that early intervention with ARVs could reduce morbidity in HIV-infected people as well as add to HIV prevention methods that exist.
"The implication is that we need to be providing treatment earlier than we do currently. The benefit to the individual receiving treatment is present whether you start late, when it's life saving, or earlier, in which case you reduce clinical events as we saw in this study. Not only is it beneficial to the individual, but it's also highly effective in reducing transmission to their partners. And that, hopefully, could be an important tool in reducing the epidemic", concludes Dr de Bruyn.