The importance of scientific research and the need for continued support for it were key themes at the 2017 International AIDS Society Conference, which took place last week in Paris.
International experts said that, while the fields of HIV treatment and prevention have seen remarkable advances in recent years, further progress is threatened by funding cuts and lack of political will worldwide.
Scientific evidence continues to show that antiretroviral therapy that reduces HIV to an undetectable level dramatically cuts the risk of transmission.
"On a global level, the biggest story was data showing that increasing antiretroviral therapy access in Africa can dramatically reduce HIV transmission, as shown in Swaziland," Dr. Steven Deeks of UCSF told the Bay Area Reporter. "With regard to prevention, the biggest story was the identification of a new vaccine candidate that will likely soon be studied in thousands of people."
The Opposites Attract study, which included more than 300 gay male couples in Australia, Brazil, and Thailand that had an HIV-positive partner on effective treatment and an HIV-negative partner, did not see a single case of transmission in nearly 17,000 reported acts of anal sex without condoms.
This adds to the evidence from the earlier PARTNER study, which looked at nearly 900 mixed-status heterosexual and gay male couples, finding no evidence of transmission between partners in more than 58,000 sex acts when the positive partner was on treatment with an undetectable viral load.
"There is no such thing as zero risk, and I think it would be foolish to say that, but we live in a society where we accept some risks," National Institute of Allergy and Infectious Diseases director Dr. Anthony Fauci told reporters. "What the data are telling us is that the risk is exceedingly low, almost to the point of being unmeasurable."
Concerned that not enough people with HIV are aware of this research, advocates want to spread the message that people with undetectable viral load cannot spread the virus. Activists interrupted a plenary session on the final day of the conference, unfurling a banner proclaiming "Undetectable = Untransmittable."
"Knowledge of the science is changing lives, it's dismantling HIV stigma, it's encouraging people to initiate and adhere to treatment, and it's getting us closer to ending the epidemic," said Bruce Richman, founder of the Prevention Access Campaign.
Expanding treatment cuts new infections
A growing body of evidence suggests that the expansion of antiretroviral treatment has begun to make a dent in new infections on a larger scale.
In advance of the conference, UNAIDS released a new report showing that 19.5 million of the estimated 36.7 million people living with HIV worldwide are now receiving antiretroviral therapy �" the first time more than half are on treatment.
"We met the 2015 target of 15 million people on treatment and we are on track to double that number to 30 million and meet the 2020 target," said UNAIDS Executive Director Michel Sidibé. "We will continue to scale up to reach everyone in need and honor our commitment of leaving no one behind."
Researchers at the conference presented data from Swaziland, which has one of the world's worst HIV epidemics, showing that new infections have been cut almost in half as the number of people on effective treatment has doubled.
"This is a great demonstration of the power of treatment and viral suppression at a population level," Dr. Susan Buchbinder, director of the San Francisco Department of Public Health's Bridge HIV program told the B.A.R. But, she added, "it's likely that we'll need more than just treatment to control the epidemic," including PrEP and a preventive vaccine.
Last week the Centers for Disease Control and Prevention released new findings showing that the United States is doing better at curbing HIV than previously thought.
Data from 2014 (the latest available) show that 85 percent of people living with HIV have been diagnosed, 75 percent of those diagnosed were linked to medical care within a month, and 58 percent of diagnosed individuals �" or 49 percent of all HIV-positive people �" are on treatment with an undetectable viral load. But these figures mask some notable disparities between groups, with young people less likely to be diagnosed or successfully treated.
Coinciding with the increase in diagnosis and treatment, the CDC reported earlier this year that new infections have finally started to decline after remaining at about the same level for two decades.
On the local level, San Francisco and London have both seen substantial declines in new infections, which experts have attributed to a combination of more HIV-positive people on effective treatment and more HIV-negative people using PrEP.
PrEP, too, was a major topic at the conference. The French Ipergay trial previously showed that taking Truvada (tenofovir/emtricitabine) "on demand" before and after sex reduced the risk of HIV infection among gay men by 86 percent. But many of the men in the study were having sex so often that they were essentially taking PrEP most of the time.
Follow-up data presented last week showed that intermittent PrEP also works for men who had sex less frequently. Taking PrEP less often would reduce the cost and could calm concerns about side effects, but currently only once-daily Truvada is FDA-approved for PrEP in the United States.
On the HIV vaccine front, early results from the APPROACH study, which included nearly 400 HIV-negative volunteers in the United States, Thailand, and countries in Africa, showed that an experimental vaccine regimen was well tolerated and generated immune responses against HIV. But larger and longer studies will be needed to determine its effectiveness.
All of this research requires a continuing influx of resources, research groups noted.
"We cannot achieve ambitious global goals, provide lifelong treatment to the 37 million people living with HIV, and reduce the epidemic without an unfaltering commitment to research," according to the Paris Statement, the latest IAS policy declaration released ahead of the conference. "Political commitment to sustained and predictable investment in a robust HIV science agenda must be strengthened ... to ensure that scientific progress against the epidemic is maximized and that gains are not lost."