The End of AIDS? Could Universal Testing and Treatment End the Epidemic?
Living in the Real World
At the 2010 Retrovirus conference, Moupali Das-Douglas from the San Francisco Department of Public Health reported that a 40% decrease in average community viral load between 2004 and 2008 -- from about 24,000 to 15,000 copies -- was associated with a 50% reduction in new HIV diagnoses (both recent infections and newly diagnosed existing infections).
By 2008, about 80% of newly diagnosed individuals were linked to care, about 90% of them started HIV treatment, and 75% achieved an undetectable viral load. The researchers concluded that these findings "support the hypothesis that wide-scale early [HIV therapy] can have a preventive effect at a population level." Community viral load can serve as a "virometer," or a way to "take the temperature" of a community, Das-Douglas explained. "This helps us see how well treatment is working, but also how well prevention is working, so we can target interventions to those at highest risk."
Julio Montaner's team has also seen evidence that their mathematical models reflect real-life outcomes in British Columbia, where the epidemic is largely driven by injection drug users in Vancouver's Downtown East-side district. In 2009 they reported changes in community viral load and new HIV infections in a group of 2,000 injection drug users. The median community viral load declined steadily, from about 55,000 copies in 1996 (when less than 10% were taking treatment) to about 8,000 copies in 1998, to below 1,000 copies in 2000. And community viral load was a stronger predictor of new HIV infections than homelessness, syringe sharing, or unprotected sex.
Montaner's team later found that between 2004 and 2009 -- a period that saw stepped-up efforts to expand HIV treatment for drug users -- community viral load decreased and the proportion of HIV-positive people with undetectable virus rose from about 40% to about 75%. During the same period, new HIV diagnoses among injection drug users declined steeply, from 150 in 2004 to 80 in 2009. They reported that between 1996 and 2009, the number of people taking HIV drugs in British Columbia increased by 547%, while new HIV diagnoses fell by 52%. For every 100 additional people who started treatment, they calculated that new diagnoses fell by 3%.
In the wake of these findings, British Columbia has invested nearly $50 million in a four-year pilot project called "Seek and Treat" that will try to expand access to HIV treatment for "hard-to-reach" populations including injection drug users, sex workers, and men who have sex with men.
"The more people you put on therapy, the less transmission there is," said Anthony Fauci, Director of the U.S. National Institute of Allergy and Infectious Diseases (NIAID), which helped fund the study. The decrease in new cases "likely could not be explained by anything else." He named test-and-treat as one component of a three-part strategy for controlling the HIV epidemic, along with pre-exposure prevention and finding a functional cure. The National HIV/AIDS Strategy, released this past July, prominently features a TLC approach.
A Little TLC
NIAID has launched a pilot study of TLC in Washington, D.C., and the Bronx, New York -- among the highest HIV prevalence cities in the country. Rachel Walensky and the Cost-Effectiveness of Preventing AIDS Complications (CEPAC) team recently reported findings from a mathematical model that estimated that universal testing in Washington, D.C., followed by immediate HIV treatment could increase life expectancy by one to two years and reduce transmission by 15% to 27%. "Test-and-treat will save lives, but it won't stop the HIV epidemic in its tracks all by itself," Walensky said. "It is only a single new and important page in the HIV-prevention playbook."
San Francisco has taken a different route with a new city-wide policy, announced this past spring, to offer treatment to everyone with HIV, regardless of CD4 cell count. "Based on accumulated data we believe all HIV-infected people should be treated with antiretroviral therapy unless there is a strong reason not to," said Department of Public Health Director Mitch Katz. But, he emphasized, "we don't dictate medical practice by policy," and the ultimate decision will remain with patients and their providers.
Public health officials acknowledge that widespread early treatment will likely drive down community viral load and prevent new infections, but the Positive Health Program doctors at San Francisco General Hospital who spearheaded the change said they were primarily motivated by benefits for individuals.
At a packed forum in April, Steven Deeks, whose team at the University of California San Francisco has pioneered research on HIV and inflammation, explained the rationale behind the policy shift. "We should perhaps think of AIDS as acquired inflammatory disease syndrome," he suggested. "Five years ago we said drugs are no fun and we should wait, but the consequence of waiting is that people develop irreversible harm to the immune system. The new paradigm is that while today's drugs are not totally benign, they are less toxic than the virus," he continued. "If I'm wrong, we'll start people [using treatment] a couple years earlier than we otherwise would. But if I'm right and we don't start early, there's no going back."
The policy has generated considerable controversy. San Francisco-based HIV advocacy group Project Inform issued a statement supporting the city's new policy. Other advocacy groups, including New York's Treatment Action Group, decided not to take a position on test-and-treat and earlier therapy until more information is available about long-term risks and benefits.
A recently opened international trial called START -- Strategic Timing of Antiretroviral Treatment -- is designed to provide such data. HIV-positive people with a CD4 count above 500 will be randomly assigned to either start combination therapy right away or delay treatment until their CD4 count falls to 350. The study will look at outcomes like death, progression to AIDS, and serious non-AIDS conditions. But START is not expected to produce results until around 2015, and some public health officials don't want to wait.
On the other side, test-and-treat skeptics express concerns about unknown long-term drug toxicities, drug resistance, and of course the added cost of providing treatment for people whose immune systems are still working well. Some have even implied that drug company profits were motivating the push for expanded testing and early treatment.
"The seeming simplicity of preventing new infections through the [test-and-treat] approach is appealing. But that simplicity hides deeply disturbing truths, including that many people coerced into unnecessary treatment will suffer side effects and treatment-induced diseases," POZ magazine founder Sean Strub wrote on his blog. "It is unethical and irresponsible to coerce or encourage people who are not recommended for treatment under the guidelines to start therapy without fully informing them of the risks."
"It is an experiment based on a mathematical model," he continued. "It is as though a decision has been made to redirect the country's public health response [to] AIDS from proven behavioral interventions, like condoms and prevention education, to the use of antiretroviral medications. Public health officials' focus on treatment as prevention and the pharmaceutical industry's incentive to expand markets are now in dangerously perfect alignment."
To address such concerns, Project Inform clarified its statement, emphasizing support for the more comprehensive approach dubbed Testing and Linkage to Care Plus (TLC+). The revised policy urges people to find out if they are HIV positive and if so, to get into care to address all the medical, psychological, and social issues they may face. Only then would they make a decision with their doctors about whether they are ready for and could benefit from HIV treatment.
"TLC+ is firmly rooted in principles of informed choice by HIV-positive people regarding all aspects of their care, particularly decisions about whether to be tested and when to start HIV treatment," the statement said. "Project Inform views it as ethical and empowering of people with HIV to describe treatment as a possible support for prevention. We believe that most HIV-positive people are altruistic and willing to factor the possible benefits for prevention into their treatment decisions."
The Beginning of the End?
While the debate continues, the idea of treatment as prevention has already been widely embraced by medical experts and public health officials. On a global level, WHO announced last year that scaling up access to HIV therapy is important for both individual clinical benefit and for prevention of new infections.
UNAIDS included treatment as prevention as part of its five-pronged "Treatment 2.0" strategy announced this summer in Vienna. The new approach could prevent up to a million new HIV infections per year if therapy were provided for all people who need it under the latest WHO guidelines, tripling coverage from the current 5 million people to 15 million.
Most experts are hesitant to predict that universal testing and treatment could completely halt the epidemic, but many think it would help bring it under control.
"Both syphilis and tuberculosis were pandemic at the end of the nineteenth century, and both epidemics were controlled by effective diagnosis and treatment," pioneer AIDS researcher William Haseltine wrote in a 2009 essay in The Atlantic. "So, too, might the current HIV/AIDS pandemic be slowed until vaccines are someday available."
Over the past 20 years HIV treatment has seen great advances, but much remains to be done, said Montaner. "I hope Vienna will go down in the history of the epidemic as where we concur that treatment is not just good for patients but also for public health, because treatment is prevention."
Liz Highleyman is a freelance medical writer and journalist based in San Francisco.
This article was provided by ACRIA and GMHC. It is a part of the publication Achieve. Visit ACRIA's website and GMHC's website to find out more about their activities, publications and services.
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