Researchers once again confirm: It's impossible for HIV-positive people on treatment to transmit the virus through sex -- this time among gay men.
Zero risk of HIV transmission via condomless sex. That is what the world's largest study among HIV-positive gay men, who are on effective antiretroviral (ARV) treatment, has found.
The results were revealed at the 22nd International Aids conference in Amsterdam on Tuesday.
The study, known as the Partner 2 study, followed close to 1 000 gay couples, of which the one person had HIV and the other was HIV negative, between 2010 and 2017. Couples were selected from 14 European countries.
Although previous studies have produced similar results for heterosexual couples, and small observational studies have been conducted among men who have sex with men, "the level of evidence for gay men remained less than for heterosexual couples", the study authors point out.
The Joint United Nations Programme on HIV and Aids has identified men who have sex with men as one of the "key population" groups that are particularly vulnerable to contracting HIV.
In the Partners 2 study, HIV-negative partners were tested for the virus every six to twelve months and also filled out sexual behaviour questionnaires. They were only included in the trial if they reported having condomless anal sex, did not take the HIV prevention pill or post-exposure prophylaxis (medication people can take after they had been exposed to HIV to reduce their chances of infection).
HIV-positive partners had to be on ARV treatment and, as a result be virally suppressed. Studies have shown that people are virally suppressed when treatment has reduced the amount of HIV in their bodies to such low levels that laboratory-based viral load testing can't detect it.
Although ARVs cannot cure someone from HIV, the medication, if taken as prescribed, suppresses the replication of the virus.
The couples reported a total of 74 567 condomless anal sex acts - more or less 42 acts per couple per year, or three to four acts per month. About a third of the HIV-negative men also had anal sex outside of their relationships.
The risk of contracting HIV from anal sex is about 18 times greater than that associated with vaginal sex, 2010 research published in the International Journal of Epidemiology shows.
At the end of the study, only 17 HIV-negative men had been infected, but genetic tests revealed that none of those infections could be linked to their HIV-positive partners, "giving a precise rate of within-couple HIV transmission of zero [for condomless anal sex]", the study authors said.
"About 77 000 of condomless sex acts among gay men resulted in not a single case of HIV transmission," the lead author of the study, Alice Rodgers from University College in London, said. "It clearly reconfirms that undetectable translates to untransmittable [U=U]."
If your partner is HIV-positive & virally supressed - or has an undectable viral load - "you'd have to have condomless sex for 420 years to get HIV," says Allison Rodgers of the new PARTNERS2 study among MSM. #uequalsu #AIDS2018 https://t.co/tolfngDtgW - Bhekisisa M&G Health (@Bhekisisa_MG) July 24, 2018
U=U is a scientifically proven concept that people with HIV who take ARVs daily as prescribed, and achieve and maintain an undetectable viral load, have effectively no risk of transmitting the virus to someone else through sex.
In November 2017, more than 500 organisations and scientists from 67 countries, including South Africa, signed on to an international consensus statement supporting U=U.
Although U=U does not protect someone against unwanted pregnancies or contracting other sexually transmitted infections, it does protect them against contracting HIV.
"U=U is one part of a set of ways that people can use to reduce their risk of HIV infection, including condoms, STI screening and pre-exposure prophylaxis (the HIV prevention pill), Kevin Rebe from the Anova Health Institute told Bhekisisa in December.
"Condoms alone could prevent most HIV transmissions. But, in the real world, it is obvious that some people can't or won't use condoms consistently and effectively. For people like this, U=U provides a powerful HIV prevention tool, even in the face of risky sex."
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