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Testimony on Update on the U.N. HIV/AIDS Program by Anthony S. Fauci, M.D.
Director
National Institute of Allergy and Infectious Diseases
National Institutes of Health
U.S. Department of Health and Human Services

Before the House Committee on International Relations
September 16, 1998

Mr. Chairman and Members of the Committee, I am pleased to appear before you today to discuss the human immunodeficiency virus (HIV) epidemic, recent developments in HIV research, and the many challenges that remain in the fight against HIV and the acquired immunodeficiency syndrome (AIDS).

The scope of the epidemic

HIV continues to exact an enormous toll throughout the world, in human and economic terms. In the United States, the rate of new HIV infections -- approximately 40,000 per year -- continues at an unacceptably high level, despite an encouraging downturn in new AIDS cases and AIDS-related deaths.

In the developing world, the epidemic is accelerating, notably in sub-Saharan African, southeast Asia and on the Indian sub-continent. According to adetailed, country-by-country analysis of HIV prevalence released earlier this year by UNAIDS, approximately 5.8 million people worldwide were newly infected with HIV in 1997 alone. More than 90 percent of these new infections occurred in developing countries, where antiretroviral therapy is beyond the reach of all but the privileged few. Alarmingly, in 27 developing countries, HIV prevalence more than doubled between 1995 and 1997. The prevalence of HIV infection is highest in the African nations of Botswana and Zimbabwe, where more than 25 percent of adults are now HIV-infected.

Globally, one in every 100 adults 15 to 49 years of age is HIV-infected; at least 80 percent of these infections are due to heterosexual transmission. By the end of 1997, an estimated 30.6 million people worldwide were living with HIV/AIDS, including 1.1 million children younger than 15 years of age. Since the beginning of the HIV/AIDS epidemic, at least 8.2 million children younger than 15 have been orphaned because of the premature deaths of HIV-infected parents.

Clearly, HIV remains one of the greatest threats to global health, and requires a sustained commitment by the various partners in AIDS research and prevention: U.S. and foreign government agencies, UNAIDS, non-governmental and philanthropic organizations, academia, industry, and the activist community. Sadly, we recently lost two of the most valiant soldiers in the battle against AIDS: Dr. Jonathan Mann and his wife, Dr. Mary Lou Clements-Mann. Collectively, we must strive to accomplish the goals to which these outstanding individuals dedicated their lives.

Antiretroviral therapies

As noted above, new AIDS diagnoses and deaths have dropped significantly in the United States and other developed countries in the past two years. These trends are probably due to several factors, particularly the increased use of potent, albeit expensive, combinations of HIV drugs. Eleven antiretroviral drugs are now licensed in the United States, and several new agents are in the final stages of clinical testing and should become available soon. Consensus guidelines have been developed for the use of anti-HIV medications, and, when appropriately applied, have greatly improved the prognosis for HIV-infected individuals.

Unfortunately, many HIV-infected individuals have not responded adequately to the medications, cannot tolerate their toxicities, or have difficulty complying with complex dosing schedules and substantial pill burdens. In addition, the ability of HIV to mutate and become resistant to the current drugs is a persistent threat. Although there is some evidence of immune system reconstitution in certain patients who receive combination antiretroviral therapy, the goals of completely "rebuilding" the immune system or eradicating the virus from the body appear unlikely with current approaches to treatment.

For these reasons, the development of the next generation of therapies remains a priority. Currently, all licensed antiretroviral medications are directed at one of two viral enzymes, but many new strategies are being pursued, including drugs that prevent the virus from entering a cell, and approaches to boosting an infected person's immune response.

HIV prevention

In developing countries where per capita health care spending may be only a few dollars a year, discussion of antiretroviral drugs is largely academic, since combination therapy and attendant care may cost upwards of $15,000 per year. Therefore, a continued emphasis on effective, low-cost tools of HIV prevention is crucial to slowing the epidemic.

Researchers have shown that several approaches to HIV prevention can reduce the number of new infections when properly executed, including: education and behavior modification; the social marketing and provision of condoms; treatment of other sexually transmitted diseases; drug abuse treatment (for example, methadone maintenance for injection drug users); and the use of antiretroviral drugs to interrupt the transmission of virus from mother to infant. For example, a recent study supported by the Centers for Disease Control and Prevention (CDC) found that HIV transmission from mother to child could be reduced by 50 percent by giving the drug AZT to mothers during the last four weeks of pregnancy and during labor and delivery.

Other methods of preventing HIV transmission also may have an important impact on slowing the epidemic. For example, researchers are developing and testing topical microbicides, substances that a woman could use in her vagina before sex to prevent the transmission of HIV and other sexually transmitted diseases. UNAIDS and others also have facilitated the widespread use in Africa of the female condom. These interventions may help empower women to protect themselves in situations where they are unable to avoid sex with partners who are HIV-infected or to persuade their partners to use a condom.

HIV vaccine development

The development of a safe and effective vaccine for HIV infection remains the "holy grail" of AIDS research, and an important step toward bringing the HIV epidemic under control. To speed the pace of HIV vaccine discovery, many public and private agencies have dramatically increased the resources devoted to HIV vaccine research. For example, at the National Institutes of Health (NIH), HIV vaccine funding increased by nearly 80 percent between FY 1995 and the estimated NIH budget for FY 1999. As part of this expanded effort, NIH has awarded numerous grants to foster innovative research on HIV vaccines, and is invigorating and reorganizing its vaccine clinical trials effort. In addition, NIH has established a Vaccine Research Center within the NIH intramural research program to stimulate multidisciplinary vaccine research.

HIV vaccine developers face a number of formidable obstacles, such as the variability of the virus and an incomplete understanding of the specific immune responses that may protect individuals from infection. However, there are many reasons to be optimistic that a safe and effective HIV vaccine can be developed. Perhaps most compelling is the fact that the human immune system can control HIV under certain circumstances. Experimental vaccines have protected animals from an HIV-like virus known as the simian immunodeficiency virus, and candidate HIV vaccines have elicited immune responses and been proven to be safe in early stage trials in humans.

As part of a broad portfolio of research, recent studies supported by the NIH have assessed so-called "vectored vaccines": harmless viruses (e.g. canarypox) which are genetically altered to make HIV proteins. These vaccines have been administered to volunteers in combination with a separate vaccine made of a purified HIV protein. Results have been encouraging: in phase I and phase II studies, the combination approach has appeared safe and evoked several types of immune responses that may have a role in protection from HIV. NIH-funded researchers are now comparing three different vectors, as well as other HIV proteins to determine which combination produces the most robust immune response. These studies, as well as additional data that emerge from basic research, will provide the information to determine which products will advance into larger-scale testing.

Meanwhile, a large-scale study of a vaccine based on the surface proteins of two HIV strains was recently undertaken in the United States by a private company, with an additional phase III study to be conducted in collaboration with CDC in Thailand. NIH will collaborate with the company in evaluating the immunological responses to the vaccine.

Conclusion