By Julio Montaner, OC, OBC, MD, FRCPC, FCCP
The latest findings from a major international study support the already strong case that consistent and sustained HIV antiretroviral treatment prevents new HIV infections. In findings released in The Lancet, the PARTNER study found no cases of HIV transmission through condomless sex among gay couples in which one partner was living with HIV on treatment and the other was HIV-negative. These results follow previous PARTNER study findings showing no cases of HIV transmission in more than 58,000 instances of condomless sex among serodiscordant homosexual and heterosexual couples.
The results of the PARTNER study definitively show that consistent and sustained HIV treatment absolutely eliminates the risk of HIV transmission to sexual partners, equally among heterosexual and homosexual couples. The PARTNER study is bolstered by a decade-long history of scientific research by the BC Centre for Excellence in HIV/AIDS (BC-CfE) and other leading scientific institutions supporting access to HIV treatment as a means to control the epidemic.
The made-in-BC Treatment as Prevention¨ (TasP¨) strategy-providing earlier and free access to HIV testing and immediate, supported and sustained access to HIV treatment-is key to curbing HIV and ending AIDS. TasP¨ forms the basis of the UNAIDS plan to end AIDS as a pandemic by 2030 by hitting ambitious-but reachable-targets for expanding access to HIV testing and sustained HIV treatment.
It is now widely accepted in the scientific and medical community that an individual living with HIV should access antiretroviral treatment at the earliest possible time and maintain treatment for life to prevent AIDS-related morbidity and mortality. Antiretroviral treatment stops HIV replication and, therefore, drives HIV to undetectable levels in biological fluids, including blood, semen and cervico-vaginal fluids. As a result, people with HIV on antiretroviral treatment do not transmit the virus to others.
Scientists, researchers, health care providers and community members have taken up the bullhorn on this message. TasP¨ has provided a foundation for the Undetectable equals Untransmittable campaign (U=U). The BC-CfE was an early signatory to the U=U statement. In order to reduce stigma for those living with HIV, it is critical for this message to reach a broad audience that includes the general public and leaders in government.
One of the major hurdles we face in achieving the global goal of ending AIDS is ensuring that international funding continues to address the ongoing HIV epidemic. Globally, there are about 5,000 new HIV cases per day. Despite having the available tools to end AIDS, funding for HIV and AIDS has plateaued at a time when we urgently need to ramp up access to testing and treatment.
These latest findings emphasize that we need to put the pedal to the metal in our efforts to curb HIV and end AIDS. The arrival of the latest results of the PARTNER study could not come at a more opportune time as we approach the next round of financing for the Global Fund. We can only hope that the new results will help persuade countries around the world to strengthen their financial contributions to the Global Fund, so that we can deliver on the promise of the made-in-BC Treatment as Prevention¨ (TasP¨) strategy.
Dr. Julio Montaner is the Executive Director and Physician-in-Chief of the BC Centre for Excellence in HIV/AIDS.
A brief history of the science supporting TasP¨ and U=U
It was shortly after the rollout of the lifesaving highly active antiretroviral therapy (HAART), in 1996, that ecological data from Taiwan and British Columbia suggested new HIV diagnoses had decreased-even amid a steady rise in syphilis cases. This made an early case for HIV Treatment as Prevention¨ (TasP¨) that the BC-CfE began investigating.
In 2006, a landmark BC-CfE paper by Dr. Julio Montaner was published in The Lancet,”The case for expanding access to highly active antiretroviral therapy to curb the growth of the HIV epidemic”. Presented at the AIDS Conference in Toronto, the world-leading research used demographic and mathematical models to show maximal coverage for antiretrovirals could lead to the near elimination of AIDS related morbidity and mortality, as well as HIV transmission.
Through the implementation of TasP¨ with support from the BC Government, BC has successfully reduced HIV transmission-from a peak of more than 850 new cases per year to less than 200 per year in 2018. BC is the only Canadian province to implement TasP¨, expanding access to earlier free HIV testing and offering universal access to sustained free HIV treatment immediately upon diagnosis. As a result, BC has seen the largest decline in new HIV cases in Canada.
BC is a recognized leader in the fight against HIV. A number of international jurisdictions have adopted the proven-effective strategy to address their own epidemics. In 2011, China was the first nation to adopt TasP¨ and a partnership between the BC-CfE and the China Centre for Disease Control and Prevention (China CDC) was renewed in late 2018. The World Health Organization and the United Nations have formally adopted TasP¨ as a the key for controlling HIV globally.
Further background
The PARTNER study is the largest and longest study assessing risk of HIV transmission between serodiscordant couples. The first phase of the multi-site international European study (PARTNER1) enrolled heterosexual and gay couples at 75 centres in 14 countries. More than 58,500 instances were recorded of condomless sexual intercourse between couples in which one couple had HIV and the other did not. The PARTNER1 study found zero cases of HIV transmissions from a positive partner on antiretroviral treatment to their HIV-negative partner.
Couples recruited had to already be having sex without condoms. To be included in the results, viral load had to be undetectable at the most recent test. Undetectable in this study was defined as being less than 200 copies/mL.
The latest iteration of the multi-site study (PARTNER2) exclusively followed gay couples, in which one partner was living with HIV and the other was HIV-negative. As with PARTNER1, no cases of HIV transmission were linked to HIV-positive partners in PARTNER 2. Some instances of HIV seroconversion occurred, but were linked to sex with other partners outside of the couple.