Global AIDS Fight Continues Despite Challenges
Washington - Despite global economic challenges and 2.7 million new HIV/AIDS infections every year worldwide, U.S. officials at the front lines of the pandemic promise increased funding and modified strategies for preventing the spread of the disease.
The most powerful prevention tool would be a vaccine, and for the first time in 20 years of research, a vaccine candidate used in a 2009 Thailand clinical trial sponsored by the U.S. Army showed a modest ability to prevent HIV infection among those who were vaccinated. But more work is needed to produce an effective vaccine.
The United States, one of the world's largest contributors to the fight against HIV/AIDS in developing countries, funds its efforts through the Obama administration's Global Health Initiative ( http://www.america.gov/st/peacesec-english/2009/May/20090507095154dmslahrellek0.7992975.html ) (GHI). A cornerstone of the initiative is the President's Emergency Plan for AIDS Relief, called PEPFAR ( http://www.pepfar.gov/ ), and the Global Fund to Fight AIDS, Tuberculosis and Malaria ( http://www.america.gov/st/texttrans-english/2009/December/20091201154041eaifas0.2512934.html ).
During PEPFAR's initial phase (2004-2008), the United States invested nearly $19 billion in PEPFAR, bilateral HIV/AIDS and tuberculosis programs, and contributions to the Global Fund, according to a PEPFAR fact sheet. In fiscal 2009, the United States provided another $6.6 billion for PEPFAR, and the president's 2010 budget asked for $6.7 billion.
"There is no doubt that there is ongoing, unmet need for HIV prevention, treatment and care," U.S. Global AIDS Coordinator Dr. Eric Goosby wrote May 27 in a State Department blog post ( http://blogs.state.gov/index.php/site/by_author/egoosby/ ). "That's why, as part of the GHI, we are increasing funding for PEPFAR and doing so in a very tight fiscal environment."
President Obama's 2011 budget request for PEPFAR, Goosby said, "is the largest request to date in a president's budget, and the program is slated to increase in the years ahead."
PREVENTION IS KEY
Part of the challenge of fighting HIV/AIDS is that on the ground, in communities, there is no single intervention that can prevent HIV infection. The biggest barrier to prevention, Goosby told America.gov in a written statement, is the challenge of delivering combinations of mutually reinforcing, continually evaluated interventions that are tailored to the needs and risks of different populations.
Some of the most successful interventions include using anti-retroviral drugs to prevent mother-to-child HIV transmission, circumcision for male adults, and providing services for injecting drug users.
"At the country level, multiple epidemics exist within diverse populations and social networks, including concentrated epidemics within larger generalized epidemics," Goosby said.
"Identifying and targeting interventions to match these needs is difficult, especially when such epidemics involve groups that are often marginalized and discriminated against," he said. "Stigmatized populations are frequently hidden and hard to reach with services. PEPFAR will support efforts to address the prevention, care and treatment needs of most at-risk populations."
Treatment with anti-retroviral drugs also can be a form of prevention.
"If you get the virus level down in people who are infected, they are much less likely to infect other people," Dr. Anthony Fauci, director of the U.S. National Institute for Allergy and Infectious Diseases (NIAID ( http://www.niaid.nih.gov/Pages/default.aspx )), told America.gov.
"The best hope [for halting the HIV/AIDS pandemic]," he said, "is a combination prevention program that includes treatment of infected individuals as prevention against further spread."
MODEST EFFECT
In September 2009, a six-year clinical trial ( https://www01.hjf.org/apps/internet/hivnewscenter.nsf/phase3 ) involving more than 16,000 mostly heterosexual adults in Thailand showed a vaccine candidate to be safe and to have a modest 31 percent effective rate in preventing HIV infection.
Led by principal investigator Dr. Supachai Rerks-Ngarm of the Thai Ministry of Public Health's Department of Disease Control, the study was sponsored by the U.S. Army in collaboration with NIAID, Sanofi Pasteur and the South San Francisco company Global Solutions for Infectious Diseases. The vaccine was based on the subtype B and E HIV strains that commonly circulate in Thailand. The subtype B HIV strain is the one most commonly found in the United States.
Although it was the first time scientists received a positive signal in any HIV vaccine trial, Fauci said, 31 percent is not effective enough to distribute the vaccine widely.
"In my own opinion as a vaccinologist and as a researcher," he said, "I think we have to at least get to 60 percent. Optimum would be 85 percent or 90 percent, but I don't think that's going to be feasible."
The problem is the nature of the HIV virus.
"In most vaccines, the body's natural response to the virus in question usually gives you a big hint that the body is capable of mounting a protective response," Fauci said. "Even though we're dealing with high-morbidity and sometimes significant-mortality diseases like smallpox, polio, measles and hepatitis, at the end of the day, even without a vaccine, the body ultimately mounts a response that clears the virus and leaves you with long-lasting and sometimes lifelong protection. That just is not the case with HIV."
For reasons scientists still don't understand, he said, the body does not readily mount a good immune response against HIV. An effective vaccine will have to do a better job than the body does at producing a strong response to the virus.
Since the clinical trial in Thailand, Fauci said, scientists are working to understand the vaccine's effect so they can enhance it in the next vaccine candidate. They are also doing fundamental research to explore new types of vaccine candidates.
