In the largest study of its kind, European researchers have concluded that the chances of a HIV positive person on successful antiretroviral treatment infecting a partner with the virus is ‘minimal’ – even if they regularly engage in penetrative sex without a condom.
Looking at 888 sero-different couples (where one is HIV positive and one is HIV negative), none of the HIV positive partners infected their partners during the course of the study. Previous research has estimated that the reduction in risk of transmission was around 93%.
The PARTNER study was carried out by researchers at University of Liverpool, University College London, Royal Free NHS and Danish hospital Rigshospitalet. Results were published yesterday in the Journal of the American Medical Association (JAMA).
Researchers monitored 888 couples from 14 different European countries over the course of several years (all recruited between 2010-2014; average study length 1.3 years). Of these, 548 were heterosexual and 340 were gay men.
All the HIV positive volunteers in the study were successfully responding to antiretroviral treatment; they had suppressed HIV levels for more than six months when starting the study.
In total, over 40,000 incidents of condomless sex were reported by the couples but none are known to have led to any HIV transmission.
Other surveys have found similar results, but they have tended to look only at heterosexual couples and were smaller in scale.
Eleven individuals became infected in study – but not from sex with their partner
Researchers noted that 11 individuals did become HIV positive during the course of the PARTNER study. However, from studying the DNA of the virus, they concluded that these individuals had not become positive from their long-term partners but from other sources (i.e. from possibly having condomless sex with other people).
Liverpool University’s Professor Anna Maria Geretti, said: ‘The HIV virus can be divided into several sub-groups, each with its own genetic characteristics, and this makes it possible to see whether the virus is genetically similar to a partner’s. In all cases the results showed that the virus came from someone other than the partner under treatment.’
They cautioned that couples who agreed to take part in the study may not be typically representative of the wider HIV community, and that the HIV positive people studied may have been more motivated to strictly adhere to their HIV treatment.
They say that all had virtually undetectable levels of virus (plasma HIV RNA levels less than 200 copies/mL).
Professor Jens Lundgren from Rigshospitalet, senior author of the study and head of CHIP (the Centre for Health and Infectious Diseases), said in a statement: ‘The results clearly show that early diagnosis of HIV and access to effective treatment are crucial for reducing the number of new HIV cases.
‘As soon as a patient with HIV is on treatment with a suppressed viral load, the risk of transmission becomes minimal.’
‘This is one of the biggest developments in our knowledge of HIV’
Despite Ludgren describing the risk as ‘minimal’, JAMA concludes, ‘the risk is not zero and the actual number is not known, especially for higher-risk groups such as MSM [men who have sex with men].’
Gay couples in the study will continue to be monitored for a further three years to obtain further data – particularly in relation to anal sex. Of the heterosexual couples in the study, 20% also reported engaging in anal sex.
The news will be welcomed by those in sero-different couplings. Those working in the sexual health field also welcomed the results.
Writing for i-Base, Simon Collins, a community representative on the steering committee of the PARTNER study, said that although no risk can ever be regarded as zero, the findings provide, ‘the strongest estimate of actual risk of HIV transmission when an HIV positive person has undetectable viral load – and that this risk is effectively zero.’
Dr Michael Brady, Medical Director at Terrence Higgins Trust, said, ‘We can now say with confidence that if you are taking HIV medication as prescribed, and have had an undetectable viral load for over six months, you cannot pass HIV onto your partner, with or without a condom. The risk is effectively zero.
‘This is one of the biggest developments in our knowledge of HIV since effective antiretroviral therapy was first introduced around 20 years ago. It has the potential to dispel the stigma, discrimination and myths that so many people living with HIV face on a daily basis; especially around the risk of HIV transmission.’
Anthony Hayes, Vice President, Public Affairs and Policy, with New York’s GMHC, told GSN that the survey reinforced the importance of people knowing their status so that they could receive appropriate treatment.
‘GMHC has for a very long time supported putting people on antiretrovirals as soon as they as they are diagnosed with HIV. This leads to them being virally suppressed and makes it nearly impossible for them to transmit the virus. Not only do antiretrovirals help lead to an optimum health outcome, but they also act as prevention.’