0 cases of transmission in 888 gay and heterosexual couples.
The PARTNER study, which is the world’s largest study of people with HIV who have had condomless sex with their HIV negative partners, has found that neither gay men nor heterosexual people with HIV transmit the virus through unprotected sex — as long as they’re on suppressive antiretroviral treatment.
The research was a collaboration amongst scientists from the University of Liverpool, University College London, Royal Free NHS, and Rigshospitalet, one of Denmark’s largest hospitals.
The researchers monitored 888 couples from 14 different European countries — 548 heterosexual couples and 340 gay couples. All of the couples had sex regularly without using a condom, with one HIV-positive partner on an antiretroviral treatment and one HIV-negative.
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After monitoring the couples for a median of 1.3 years, the study results, which have been published in the Journal of the American Medical Association (JAMA), show that there was not one instance of transmission of the HIV virus.
However, there were 11 cases of HIV-negative partners being infected with the HIV virus in the period following the study, so the researchers from the University of Liverpool's Institute of Infection and Global Health conducted phylogenetic analyses of the 11 cases.
A phylogenetic analysis is the study of evolutionary relationships, and usually an evolutionary history is illustrated with “treelike diagrams that represent an estimated pedigree of the inherited relationships among molecules (''gene trees''), organisms, or both,” according to microbiology and immunology researchers.
Lead researcher Anna Maria Geretti explains that the HIV virus can be divided into several sub-groups, and each possesses unique genetic characteristics that would tell the researchers whether the acquired HIV virus was genetically similar to the individual’s partner’s HIV.
Through the phylogenetic analyses, the results showed that in all 11 cases, the virus came from someone else other than the partner under antiretroviral treatment.
"The results clearly show that early diagnosis of HIV and access to effective treatment are crucial for reducing the number of new HIV cases,” senior author Jens Lundgren, from Rigshospitalet and head of the Centre for Health and Infectious Diseases (CHIP), said in a press release. “As soon as a patient with HIV is on treatment with a suppressed viral load, the risk of transmission becomes minimal."
As exciting as these results are, more data is expected to surface sometime in 2018. Moving forward, the researchers will continue to monitor gay couples for three more years in order to see whether these encouraging results hold up for anal sex.
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