Confirmed and needs to be stressed: The chance of any HIV-positive person with an undetectable viral load transmitting the virus to a sexual partner is scientifically equivalent to zero.
This is according to researchers who released at #AIDS2018 the final results from the PARTNER study. Results originally announced in 2014 from the first phase, PARTNER 1, already indicated that “Undetectable equals Untransmittable” (U=U). But while the first study was lauded in tackling vaginal sex, the statistical certainty of the result did not convince everyone, particularly in the case of gay men, or those who engage in anal sex.
But now, PARTNER 2, the second phase, only recruited gay couples. The PARTNER study recruited HIV serodifferent couples (one partner positive, one negative) at 75 clinical sites in 14 European countries. They tested the HIV-negative partners every six to 12 months for HIV, and tested viral load in the HIV-positive partners. Both partners also completed behavioral surveys. In cases of HIV infection in the negative partners, their HIV was genetically analyzed to see if it came from their regular partner.
And the results indicate “a precise rate of within-couple transmission of zero” for gay men as well as for heterosexuals.
The study found no transmissions between gay couples where the HIV-positive partner had a viral load under 200 copies/ml – even though there were nearly 77,000 acts of condomless sex between them.
PARTNER is not the only study about viral load and infectiousness. Last year, the Opposites Attract study also found no transmissions in nearly 17,000 acts of condomless anal sex between serodifferent gay male partners. This means that no transmission has been seen in about 126,000 occasions of sex, if this study is combined with PARTNER 1 and 2.
While this is good news overall in the fight against HIV, related issues continue to plague HIV-related efforts, particularly in countries like the Philippines.
For instance, aside from the overall silence on U=U (undetectable = untransmittable), use of anti-retroviral therapy (ART) continue to be low. As of May 2016, when the country already had 34,158 total reported cases of HIV infection, Filipinos living with HIV who are on anti-retroviral therapy (i.e. those who are taking meds) only numbered 14,356.
The antiretroviral medicines in use in the Philippines also continue to be limited, with some already phased out in developed countries.
All the same, this is considered a significant stride, with science unequivocally backing the scientific view helmed in 2008 by Dr. Pietro Vernazza who spearheaded the scientific view that viral suppression means HIV cannot be passed via a statement in the Bulletin of Swiss Medicine.