If all HIV patients were ‘undetectable’ it could cut transmission rates by 90 percent

The JAMA Internal Medicine last week published a Centers for Disease Control study showing that 9 in 10 new HIV infections in the U.S. could be avoided as long as people living with HIV are on proper treatment.

“We were not surprised that this CDC study found a significant portion of new HIV infections arose from HIV-positive individuals who were not in care or may not even have known their HIV status; however, we were shocked to see that the number was as high as it is — nine out of ten new HIV infections in 2009 occurred this way —over 91.5 percent,” said Michael Weinstein, AIDS Healthcare Foundation President, in a prepared statement.

In another study that was released, the IPERGAY trial examined whether PrEP on demand was as successful as the once-a-day regimen that is currently prescribed. In this trial participants were to take the drug before sex and for several days after. The study found that it reduced HIV risk among MSM individuals by an average of 86 percent.

Heywood and Weinstein both have concerns about the IPERGAY study though.

"At first blush it seems clear that the IPERGAY study is limited to the most sexually active gay men, those with more than eight partners every two months, who presumably are also not using condoms,” Weinstein said. “This is a relatively small sub-set of the total gay male population and a far cry from the 500,000 men that the CDC recommended take the drug.”

While Heywood noted that because these men were so sexually active it appears they could have been taking the pill almost daily anyway reaffirming the effectiveness of Truvada to reduce the risk of HIV infection, but not much else.

“I think it proves a point of concept, but I don’t think it proves efficacy,” he said. He also that he doesn’t the concept of PrEP on demand will be very effective in the gay male community. “We are not very good at gaging when we will have sex. It just makes more sense from a prevention perspective to go with the daily dosing.”

Weinstein added that he’s worried that if PrEP on demand became the norm there could be other consequences.

“In addition, if before-and-after-sex dosing becomes the norm, it will heighten the risk of resistance since more men will be taking the drug after they have sero-converted,” he said.

This coincides with the results of the Opposites Attract study that were just released in Australia. That study followed gay males in mixed status relationships (sero-discordent couples) with the HIV positive male on medications and having an undetectable viral load. No transmissions between couples were recorded.  

Fifty-eight percent of the couples reported having condomless anal sex for a total of 5,905 times.

While over in the UK, the PROUD open-label study showed that daily usage of Truvada for PrEP reduced the risk of HIV infection by 86 percent.

“It’s Important to note that this latest study reaffirms what the original PrEP study found — when you take it, it works, when you don’t, it doesn’t — just like condoms,” Heywood said.