Researchers are optimistic about a potential HIV/AIDS vaccine, even though none of the vaccines in development is likely to completely protect people from HIV transmission, participants at the XVI International AIDS Conference in Toronto said at a news conference Tuesday, Reuters reports.
It is difficult to develop an effective HIV/AIDS vaccine because the virus infects the immune system cells that usually would be stimulated by a vaccine, according to Reuters (Fox, Reuters, 8/15). In addition, Wayne Koff, chief of vaccine research at the International AIDS Vaccine Initiative, said that no vaccine candidate thus far has been able to address all forms of HIV (Bloomberg News, 8/15). Seth Berkley -- head of IAVI, which on Tuesday released its biennial report on HIV/AIDS vaccines -- said that Merck and Sanofi-Aventis each have a vaccine candidate in late-stage human trials. Berkeley said, "The next major milestone for the field is likely to be the Merck result, which is a test for cellular immunity" (Reuters, 8/15). Merck's vaccine, which of all the vaccines in development is in the most advanced testing stages, works by improving the ability of CD4+ T cells to "seek and destroy [HIV-]infected human cells" to "prevent HIV ... from causing disease," Bloomberg News reports. The company expects by 2008 or 2009 to have some data on the vaccine and plans to conduct a clinical trial of about 3,000 people in Australia, the Caribbean and North and South America (Bloomberg News, 8/15). Berkley said that if the Merck vaccine reduces the expected number of new HIV cases even slightly, researchers will be able to evaluate the trial participants and use their findings to guide future research. If the vaccine is not at all effective, researchers will have to look at different approaches, Reuters reports (Reuters, 8/15). "The proof of concept trial is incredibly important because if it works, it will be the first time we've done something that works," Robin Isaacs, executive director of infectious disease research at Merck, said, adding, "It will merely open the flood gates for wanting to do better." GlaxoSmithKline also is working on a vaccine that is in early stages of testing, according to Bloomberg (Bloomberg News, 8/15).
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Berkley said, "An AIDS vaccine is the only tool that can end the pandemic. All evidence suggests that a vaccine is possible. There is progress being made. It's slow, but it's steady" (Reuters, 8/15). Cate Hankins, chief HIV scientist at the United Nations, said, "A vaccine's going to be critical in the long run to containing the epidemic. Unless there's some striking breakthrough that we're not aware of, it's likely to be another 10 years before one is commercially available" (Bloomberg News, 8/15). U.N. Special Envoy for HIV/AIDS in Africa Stephen Lewis said, "Even a modestly effective vaccine could cut the number of new infections by one-third over a decade, saving tens of millions of lives" (Berman, VOA News, 8/16). Gerald Voss, head of AIDS vaccine programs at GSK, said, "There's optimism, but at the same time, people have been working on this for 20 years, and we're still nowhere near a vaccine" (Bloomberg News, 8/15). According to the IAVI report, AIDS vaccine development spending in the past five years had doubled to $759 million in 2005 (VOA News, 8/16).
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