An Early End to the HIV/AIDS Pandemic?
A pioneering AIDS researcher contends that the tools to end the epidemic may already be at hand
Preliminary reports on Obama’s first budget, to be unveiled tomorrow, suggest that funding for international AIDS programs will be held flat, despite campaign-trail promises to ramp up U.S. commitment. Yet now more than ever, investment in the cause can make a difference.
Earlier this week, I met with three colleagues — Robert Gallo, Max Essex, and Robert Redfield—who have been at the forefront of AIDS research for the last 25 years. It was the four of us who in the early ’80s helped define the viral nature of the disease, developed the basis for the first diagnostic test, and established a fundamental understanding of the virus, which led directly to the development of effective treatments. We hadn’t been together in one place in about a decade, and as we got to talking at Bob Gallo’s Institute of Human Virology in Baltimore, we realized we shared a surprising conclusion: The tools to end the AIDS epidemic may well be at hand.
Paradoxically, this realization emerges at a low point in our hopes for an HIV/AIDS vaccine. The dramatic failure of the most-promising-seeming vaccine last year dashed such prospects, and sent the community of researchers back to the laboratory. Nevertheless, the epidemic could still be arrested or substantially slowed using diagnostic tests and anti-viral drugs already in existence—saving tens of millions of lives worldwide.
Epidemic control begins with knowing who is infected, so the first step is to detect all those who carry the virus. The means to monitor the progress of the disease are widely available. Reliable, inexpensive diagnostic tests exist and are being used in rich and poor countries alike. And thanks to anti-discrimination policies and the availability of effective, affordable treatments, barriers to testing are falling. In some regions, such as southern Africa, where infection rates exceed 25 percent of the adult population, testing of everyone between the ages of fifteen and fifty might be recommended. Elsewhere, as in the United States and Western Europe, testing could be more focused.
The second step is to treat all those infected with combinations of anti-HIV drugs. Advances in this area have been nothing short of spectacular. More than twenty-five new drugs are currently available, and still more are in the pipeline. When I began my work, HIV infections were almost always fatal. Today, most of those infected with HIV, if carefully treated, can expect to live many decades in relatively good health. Although it is too early to know for sure, it seems likely that the majority of those carrying the virus can expect a normal lifespan.
The effectiveness of the first therapies was limited by the rapid emergence of viruses within each patient that were resistant to a single drug. The solution was to develop sets of drugs, each acting on a different part of the virus. At present, drugs that inhibit six different steps required for virus growth are available. Using combinations of these drugs greatly slows the development of drug resistance. And when resistant viruses do emerge, different combinations of these drugs are often effective. Such progress is a triumph of modern medical science.
Initially, effective HIV/AIDS treatments were available only to those living in wealthy countries. The cost of drug therapy ranged from $10,000 to $15,000 dollars a year in rich and poor countries alike. Today, combination therapy is available in some countries for as little as $75 a year. And agencies such as the Global Fund and the U.S.-sponsored PEPFAR program provide drug treatment free of charge to many less developed countries. Thanks to this dramatic reduction in cost, more than 3 million people in poorer countries are currently receiving treatment through these and other programs. With continued support, that number will grow.
Despite such progress, however, the epidemic is outrunning treatment. The World Health Organization estimates that there are now about 35 million people infected with HIV, the great majority of them living in sub-Saharan Africa and South Asia. It is also estimated that 2 to 3 million new people are infected with HIV each year. Thus, an effective method for preventing new infections is badly needed, which is why the failure of the HIV/AIDS vaccine trials was so tragic.
In the near term, our hope for preventing new infections arises from recent observations regarding the effectiveness of diagnosis and treatment in limiting transmission: It has been found that anti-HIV/AIDS drugs reduce the spread of the virus in several circumstances. About one third of children born to infected mothers become infected with HIV. In some instances, this transmission occurs before birth, in other instances, during birth trauma. Still others are infected through breast feeding. But evidence suggests that treating the mother with anti-HIV/AIDS drugs can dramatically reduce all three types of transmission.
Preliminary studies by Max Essex, working with a team at Harvard and in Botswana, seem to show that infection of newborns falls to undetectable rates if mothers are treated with combination therapy for the six months before and after birth, providing that the child is weaned at six months. If transmission by such intimate contact as mother to child can be reduced to near zero, it seems likely that other forms of transmission can also be reduced. Several additional studies document the effectiveness of treatment in substantially reducing sexual transmission of the virus in both heterosexual and homosexual couples. Effective treatment may even reduce infections that occur via blood directly, either by transfusion or by sharing blood-contaminated needles.
How does anti-viral therapy work to reduce transmission? The ability of a person to transmit the HIV virus to another through sex or blood, or from mother to child is correlated with the amount of virus in the body—the higher the concentration of the virus, the more efficient the transmission. Effective anti-viral treatments reduce the amount of virus in the body, thereby diminishing the likelihood of transmission: the more complete the viral suppression, the lower the odds of transmission. To summarize, not only does treatment with anti-HIV drugs prolong life, it also reduces, or may in some cases eliminate, the spread of the virus from one person to another.
History has shown that epidemics can be controlled, even in the absence of a vaccine. Both syphilis and tuberculosis were pandemic at the end of the nineteenth century, and both epidemics were controlled by effective diagnosis and treatment. So, too, might the current HIV/AIDS pandemic be slowed until vaccines are someday available.
I recommend that WHO, PEPFAR and the Global Fund begin studies to assess the effectiveness of universal testing and early treatment for the prevention of HIV transmission. The joint collaboration between Harvard Medical School and the Government of Botswana, now in the advanced planning stages, is one such study. Others should follow soon.
Meanwhile, we should also continue our efforts to control the epidemic via other means: both the fundamental and practical studies needed to create an effective HIV/AIDS vaccine should be accelerated; countries and regions should increase their efforts to promote condoms and educate the public regarding the risks of infection; and programs to encourage male circumcision, shown to reduce the risk of HIV infection, should also be implemented where appropriate.
But the continued and rapid spread of HIV infection demonstrates that such measures are not sufficient to stop the epidemic. Something more is needed. I believe that our best hope now lies in universal detection and universal treatment of all those currently HIV positive. It is time to begin. We cannot afford to wait.