May 14, 2012
There is a growing consensus that we can significantly curtail the HIV/AIDS pandemic by implementing scientifically proven HIV prevention strategies, such as voluntary medically supervised adult male circumcision, prevention of mother-to-child transmission and treatment as prevention. With 2.7 million new HIV infections in 2010 alone, however, it is likely that controlling and ultimately ending the HIV/AIDS pandemic will require an effective vaccine as well. This past year, there have been a number of encouraging findings on this front.
Last month, a detailed analysis of specimens from the first HIV vaccine clinical trial to show a modest protective effect yielded important clues about how the vaccine might have worked. These clues suggest directions for improving upon the original vaccine regimen to confer a broader, more potent and longer-lasting effect. The original vaccine regimen was tested among 16,000 adult volunteers in Thailand in a trial co-funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of NIH.
Meanwhile, several other NIAID-sponsored HIV vaccine clinical trials are under way. The largest of these is examining whether a prime-boost vaccine regimen can prevent HIV infection or reduce the amount of virus in the blood of those participants who become infected despite vaccination. These trials are possible because of the generous contributions of time and effort by thousands of study participants, community educators, health care workers and scientists. All those involved deserve our gratitude.
Preclinical animal model studies of HIV infection recently have uncovered valuable leads toward designing a preventive HIV vaccine. Scientists have demonstrated that a vaccine can prevent a virulent monkey version of HIV infection and have shown a correlation between this protection and the presence of specific antibodies to the virus.
In basic HIV vaccine research, scientists are discovering and studying HIV neutralizing antibodies that shield cells in the lab against infection with a wide array of HIV strains collected from infected people worldwide. Researchers are analyzing the structure and evolution of these antibodies and the manner in which they bind to HIV, and are using this information to design new molecules to elicit the antibodies through vaccination. In related experiments, injecting these antibodies directly into monkeys has been shown to prevent infection from a monkey version of HIV. Based on these findings, studies to test this concept in people are being planned.
All of these advances reinforce our confidence that one day we will succeed at creating a safe, highly effective vaccine to prevent HIV infection. To contain and ultimately halt the HIV/AIDS pandemic, even the most effective vaccine must be part of a combination of medical and behavioral HIV prevention tools. That is why NIAID continues to support research into promising HIV prevention strategies, such as vaginal and rectal microbicides, pre-exposure prophylaxis (PrEP) and expanded HIV testing with linkage to care. That is also why the public health community will continue to refine and implement scientifically proven HIV prevention measures, including condom use, harm-reduction strategies for injection drug users, and, notably, treatment as prevention: giving antiretroviral therapy to HIV-infected individuals to dramatically reduce their infectiousness while protecting their health.
Vaccines historically have been the single most important tool for controlling epidemics. With an ongoing commitment to HIV vaccine research, we have the potential to radically change the trajectory of the HIV/AIDS pandemic.
Anthony S. Fauci, M.D., is Director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health in Bethesda, Maryland.