The PARTNER Study, a two-year study, has reported no incidence of HIV transmission by partners with a undetectable viral load.
For some time now we’ve known that having an undetectable viral load (VL) significantly reduces the chances of transmitting the virus onto partners and thus reduces the chance of infection, but in a landmark study of 1,110 couples (40% gay couples) there were no recorded transmissions of HIV between the positive and negative partners.
The PARTNER study took on 1,110 couples – 40% of which were gay. To qualify for the study the partners had to be having condomless sex “at least some of the time” with the negative partner not receiving Pre-Exposure Prophylaxis (PrEP) or Post-Exposure Prophylaxis (PEP), the positive partner had to be receiving HIV treatment and have a viral load below 200 copies/ml. A small number of couples were excluded from the study, for VL increases or having taking PrEP / PEP.
The headline news is that out of an estimated 16,400 occasions of sex in the gay men and 14,000 in the heterosexuals there have been no reported HIV transmissions within the study couples. A number of people in the study did become HIV positive but through genetic testing the the study was able to determine that the virus had come from outside of the relationship.
Alison Rogers from The PARTNER Study told CROI 2014 conference attendees that zero infections is not the same as zero percent risk. With a 95% confidence in their figures the team peg the risk per year at 0.45% to the negative partner, and 1% for those who engage in anal sex. But when asked what the study tells us about the chance of someone with an undetectable viral load transmitting HIV, presenter Alison Rodger said: “Our best estimate is it’s zero.”
This is clearly great news for those couples in serodiscordant relationships, or concerned about dating someone of a different HIV status. But we must remember that though the chance of transmission is close to zero percent, there is still a statistical chance.
The PARTNER Study is still recruiting male couples, and its final results will be out in 2017. For more information about the partner study please visit: http://www.partnerstudy.eu/