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International study of gay couples reports no transmissions from an HIV-positive partner on treatment
Gus Cairns, 2017-07-25 09:00:00
A study of 343 gay couples, where one partner had HIV and
the other did not, has not found a single case of HIV transmission in 16,889
acts of condomless anal sex, the 9th International AIDS Society Conference on HIV Science (IAS 2017) in Paris, France, was told today.
The Opposites Attract study looked at whether HIV is
transmitted between gay male couples of different HIV status when the HIV
positive partner is on treatment that fully suppresses HIV. The
HIV-positive partners in Opposites Attract had a so-called ‘undetectable viral
load’ 98% of the time.
The study recruited and followed-up gay couples at clinics
in Australia, in Bangkok and in Rio de Janeiro.
The evidence from Opposites Attract adds to the evidence from
PARTNER study that HIV-positive people on effective HIV treatment that
fully suppresses their virus cannot transmit their infection through sex. Taken
together, the two studies have not found a single case of HIV transmission in
nearly 40,000 acts of condomless anal sex between gay men.
This adds further strength to the “U=U” (Undetectable equals Untransmissible)
tagline of the Prevention Access Campaign, whose consensus statement has been
signed by Aidsmap and also by the International AIDS Society (IAS), organisers
of this week’s International Conference on
HIV Science in Paris.
The studies also found that if the positive partner is on
successful treatment, even having another STI does not increase the risk of HIV
being transmitted. In Opposites Attract, participants had an STI during 6% of
anal sex acts and in PARTNER, 17.5% of participants had an STI at some point in
Sexual position also made no difference even though when
viral load is not suppressed,
transmission is 10-20 times more likely if the HIV-positive partner is the
insertive one; in Opposites Attract, the HIV-positive partner was ‘top’ over a
third of the time.
During the Opposites Attract study, three men became
infected with HIV, but genetic analysis showed that these infections came from
a partner outside the main relationship who was not virally suppressed.
Only 0.9% of the total proportion of condomless anal sex acts happened where the HIV positive partner had a detectable viral load, and only 1.7% during their first six months on antiretroviral therapy. There
were no transmissions from men in these groups either. Presenter Andrew Grulich commented: "In our Thai site, 40% of the men who entered the study were not on antiretroviral therapy when they entered the study, but immediately started it and were rapidly virally suppressed. They were really good at using condoms and other strategies to avoid transmission while they were still detectable, so the number of condomless anal sex acts with a detectable partner was very small."
In PARTNER, despite not many more episodes of condomless
sex, there were ten such ‘unlinked’ infections in gay men. The difference may
be due to 24% of the HIV-negative partners in Opposites Attract taking PrEP.
Researcher Benjamin Bavinton told Aidsmap there was evidence that PrEP-takers
in Opposites Attract were indeed mostly taking it to protect themselves from HIV
infection from partners outside
the main relationship.
At a press conference the previous day on viral load and
infectiousness, Dr Anthony Fauci, director of the IAS National Institute for
Allergies and Infectious Diseases, said: “Scientists never like to use the word
“Never” of a possible risk.
“But I think in this case we can say that the risk of
transmission from an HIV-positive person who takes treatment and has an
undetectable viral load may be so low as to be unmeasurable, and that’s equivalent
to saying they are uninfectious. It’s an unusual situation when the overwhelming evidence base in science
allows us to be confident that what we are saying is fact.”
Dr Louis Loures, Deputy Executive Director of UNAIDS, said
that in terms of the public impact of treatment as prevention, the agency was
seeing more and more cities where HIV incidence was falling as they reached a
tipping point in terms of the number of people who are on therapy and non-infectious:
he quoted San Francisco, Sāo Paulo and Nairobi as examples.
Bruce Richman, a Harvard-trained lawyer, is the prime mover
behind the “U=U” campaign.
He said: “In
2006 when I was diagnosed, I was terrified of infecting someone I loved and was
terrified of taking a pill that reminded me every day I was infectious. But in
2012 when I finally started therapy, my doctor told me that if I suppressed my
viral load, I would become non-infectious.
turned to outrage, because every website I found was saying I was still a risk.
The breakthrough science was not breaking through to communities that needed to
know it. Doctors would tell people on a one-to-on basis while withholding the
info from those they deemed irresponsible.
collaborated with doctors to endorse the U=U consensus statement. This
is demolishing HIV stigma and encouraging people to start treatment and bring
an end to the epidemic. We need people like UNAIDS, as they did today, to
confirm it’s true.”