One STEP forward, two steps back

The quest for an HIV vaccine goes on

The past year was a disappointing one in the search for a safe and effective HIV vaccine, said Anthony S. Fauci, MD, director, National Institute of Allergy and Infectious Diseases National Institutes of Health (NIAID).

"The scientific concept tested in the HIV vaccine study known as the STEP trial was considered to have great promise; however, the vaccine did not have the desired beneficial effect," he said. "Although the finding was disappointing, it was not unusual given the nature of science and vaccine development. Historically, it has taken decades to find effective vaccines to combat infectious diseases."

For example, it took 89 years to create an effective pertussis vaccine and 42 years to develop an effective measles vaccine, and then only after researchers experienced numerous setbacks and disappointments. "Yet they persevered," he said. "Finding a safe and effective HIV vaccine demands an equally intense resolve." The veteran AIDS fighter made the comments as the 25th anniversary of the discovery of virus was noted in May as part of HIV Vaccine Awareness Day.

"Since then, over 60 million people have been infected with HIV—an estimated 2.5 million in 2007 alone—numbers that remind us that the development of an HIV vaccine is an urgent humanitarian imperative," Fauci said.

Last year, 2.1 million people died as a result of AIDS, including 330,000 children under the age of 15. Today, 33.3 million people are living with HIV infection. Although the problem is most severe in sub-Saharan Africa, the United States also has been hard-hit: more than 565,000 people in this country have died of AIDS and an estimated 1.1 million are living with HIV infection. African-Americans and Hispanics shoulder the greatest burden, accounting for 59 % of U.S. AIDS cases in 2006.

"In some urban areas, the HIV infection rates rival those of Africa," he said. "Nowhere is this more shocking than in the nation's capital, where one in 20 Washingtonians have HIV and one in 50 has AIDS."

Though much has been gained in the form of life-saving treatments, the stark reality is that for every person with HIV who is placed on therapy, about three more individuals become newly infected with the virus, he noted. "The rate of new HIV infections far outpaces our ability to supply a lifetime regimen of HIV medication to everyone who needs it," he said. "Further scale-up of lifesaving HIV treatment programs is critical. However, treatment alone will not end the AIDS pandemic."

Thus developing HIV prevention strategies, including a vaccine, remains an extremely important goal. A number of proven strategies to prevent HIV transmission are already available, including education and behavior modification; condom usage; medically supervised adult male circumcision; harm-reduction approaches such as needle and syringe exchanges for injection drug users; and antiretroviral drug regimens for HIV-infected pregnant women to prevent mother-to-child HIV transmission of the virus. NIAID is testing other prevention strategies, such as microbicide gels or creams that can be applied prior to sexual intercourse and preventive regimens of antiretroviral drugs, that we hope will prove successful. Ideally, a vaccine that prevents HIV infection would be a core component of our prevention program.

Recently, NIAID convened a scientific summit to examine the state of HIV vaccine research and determine how best to move the field forward. Based on that discussion, it became clear that although it is important to maintain our approach to identifying promising HIV vaccine candidates and clinically testing those candidates when appropriate, it also is imperative that we place greater emphasis on the basic research necessary to address the many unanswered questions that remain about HIV, Fauci noted. "We must understand how to create a vaccine that induces a protective immune response in people that is more effective than the immune response that results when someone is naturally infected with HIV," he said.