Confronting the HIV pandemic.

Abstract

I n 1998, approximately 30 million people worldwide were living with HIV/AIDS, of whom about 5 million became infected just that year. The epidemic continues to expand, with an estimated doubling time of 10 years, so that AIDS has now surpassed tuberculosis and malaria as the leading infectious cause of death. Even in the United States, where the death rate from AIDS is declining because of effective drug therapies, HIV infection rates continue to climb in a number of population groups, such as women and racial and ethnic minorities. To address this domestic and international public health crisis, the National Institutes of Health (NIH) is complementing its long-standing commitment to developing effective HIV therapies with an expanded program in HIV prevention research. This initiative has required a novel effort to cross traditional disciplinary boundaries that have impeded development and dissemination of effective prevention strategies. Thus, the NIH prevention science agenda encompasses three key components, integrated wherever appropriate: vaccines, behavioral and social interventions, and nonvaccine biomedical technologies. The intent is to develop interventions for immunizing uninfected people and for reducing the risk of transmission by sexual, parenteral, or perinatal routes. Because the NIH vaccine research effort has received substantial attention in Science and elsewhere, we concentrate here on other prevention strategies. HIV prevention strategies already have demonstrated their efficacy in the United States and internationally, including in developing countries. Behavioral- and social science-based interventions have significantly reduced the incidence of unprotected intercourse, reduced the number of sex partners, delayed sexual initiation, reduced the incidence of sexually transmitted diseases, diverted individuals from injection drug use into drug treatment programs, and reduced needle sharing and the frequency of drug injection. Safer sex practices have reduced the annual incidence of HIV infection from >15% to 30% in some settings. Even in resource-poor countries, such as Thailand, Uganda, and Senegal, national strategies based on behavioral interventions have reduced HIV prevalence by as much as 50% over a few years' time. Biomedical strategies also have demonstrated effectiveness in HIV prevention. Screening the blood supply has reduced the risk of transfusion-associated transmission of HIV by >99.9% in the United States. The use of antiretroviral therapy during pregnancy and birth has reduced transmission by about 90% under optimal conditions. The recently expanded HIV prevention science agenda at NIH looks simultaneously at the biomedical, behavioral, and social dimensions of HIV transmission and prevention. To advance a more cross-disciplinary and innovative program, the Office of AIDS Research has established a priority-setting process that involves advice from extramural scientists and community advocates and identifies areas that require concerted support because of trends in the epidemic, as well as developments in scientific knowledge. Current priorities include microbicides for women; culturally appropriate interventions for racial and ethnic minorities; validating biological and behavioral outcome measures; international prevention research; and legal and ethical issues in prevention research, programs, and policy. As we continue to develop the science of HIV prevention, the effective dissemination of proven interventions to more populations and settings remains a major challenge. To address this challenge globally, NIH is increasing its international collaborations to help develop prevention research capacity in other countries and to learn from their successes. The scientific community throughout the world must work to persuade public health decision-makers to institute community-based prevention programs based on research findings. Only then will we realize the full potential of prevention science to help stem the HIV/AIDS epidemic in the United States and around the world.