AMSTERDAM, Netherlands — Undetectable equals uninfectious has become a rallying cry of academics, activists and doctors alike when it comes to the risk of HIV transmission. On Tuesday at the 2018 International AIDS Conference, researchers confirmed the slogan when they shared the results of the PARTNER2 study for the first time.
PARTNER2 recruited gay mixed-status couples who engage in condomless anal sex to determine the risk of transmitting HIV. In order to be eligible for the study, the negative partner could not be on pre-exposure prophylaxis to prevent HIV transmission. With over 77,000 condomless anal sex acts recorded among the 635 same-sex couples, researchers found “a precise rate of within-couple transmissions of zero” for all gay men when the positive partner had an undetectable viral load.
During the press conference, one researcher said that, “The outer limit of likelihood is you would have to have condomless sex for 420 years to have one incident of HIV transmission.”
Zero cases of HIV from condomless sex between sero-different gay partners (one HIV+, one not) found in new study.
“The outer limit of likelihood is you would have to have condomless sex for 420 years to have one incident of HIV transmission.” #UequalsU#AIDS2018
— Matthew Hodson (@Matthew_Hodson) July 24, 2018
In 2017, the Centers for Disease Control and Prevention acknowledged that being undetectable means that people cannot transmit the virus, as well. Despite the various groups signing on to affirm the statement, AIDS activists have bemoaned the lack of knowledge in the general population about what it means to be undetectable. A recent study found that up to two-thirds of HIV-negative gay and bi men, or men who didn’t know their status, actually doubt the veracity of the “U=U” slogan.
PARTNER2 is the second phase of the PARTNER study, which first demonstrated that people who were undetectable in mixed-status heterosexual or queer couples did not transmit the virus. However, at the time, researchers did not have as much data on gay couples. Basically, earlier research was not as confident about whether being undetectable could also prevent transmission for couples with repeated acts of anal sex without a condom. Now, researchers are sure.
When presenting the data for PARTNER2, principal researcher Alison Rodger’s final slide affirmed “Undetectable = Untrasmittable.”
“We looked so hard for transmissions,” Alison Rodger told Aidsmap. “And we didn’t find any.”
These scientific results come 12 years after the “Swiss statement” in 2006, the first time researchers espoused the idea that being undetectable meant that people with HIV would not pass on the virus to partners.