U.S., British HIV/AIDS researchers pessimistic about prospects of vaccine, survey finds

Leading HIV/AIDS researchers in Britain and the U.S. are pessimistic about the prospects of developing an HIV vaccine following the recent failure of a Merck vaccine candidate, according to a survey conducted by London's Independent, the Independent reports (Connor/Green, Independent, 4/24).

Merck in September 2007 announced it had halted a large-scale clinical trial of its experimental HIV vaccine after the drug failed to prevent HIV infection in participants or prove effective in delaying the progression of the virus to AIDS. The vaccine candidate also might have put some trial participants at an increased risk of HIV (Kaiser Daily HIV/AIDS Report, 3/26).

To determine the sentiments of researchers, the Independent surveyed more than 35 leading HIV/AIDS scientists in the U.S. and Britain. The survey found that two researchers responded that they are now more optimistic about the prospects for an HIV vaccine than they were last year, and four said that they were more optimistic now than they were five years ago. About two-thirds said that a vaccine will not be developed within the next decade, and some respondents said it would take at least 20 years to develop a vaccine. The survey also found a "substantial minority" said that an HIV vaccine might never be developed, according to the Independent. In addition, those who said that a vaccine might be developed in the next 10 years said that such a vaccine would be unlikely to work as a "truly effective prophylactic" against HIV infection. More than 80% of the survey respondents said that because of the failure of the Merck trial, it is important to change the direction of HIV vaccine research.

According to the Independent, one of the "major conclusions" that came from the failed Merck trial was that an animal model used to test HIV vaccines on monkeys before they are tested on humans does not work. Anthony Fauci, director of NIH's National Institute of Allergy and Infectious Diseases, said the animal model, which combines HIV with the simian form of the virus, failed to predict what will occur when a prototype vaccine is moved from monkeys to people. "We learned a few important things" from the Merck trial, Fauci said, adding, "We've learned that ... the SHIV model really doesn't predict very well at all." According to Fauci, now is not the time to stop vaccine research. "I don't think you should say that this is the point where we're going to give up on developing a vaccine. I think you continue given that there are so many unanswered questions to answer," he said.

Jonathan Weber, a professor at Imperial College London, said, "There is no basis for confidently predicting we will have an effective vaccine any time soon," adding, "This isn't to say that a vaccine is impossible." William James, a professor at the University of Oxford, said, "The development of an AIDS vaccine is one of the greatest challenges facing medical research and is going to be a long-term effort" (Independent, 4/24).

Related Opinion Piece

The "failure" of the Merck trial is "widely seen as a major setback," but the "time to give up on an HIV vaccine has not yet come, and perhaps it never will," Steve Connor, science editor for the Independent, writes in an opinion piece. "Trying to develop an HIV vaccine is a bit like digging a hole in the ground," Connor writes, adding, "The question is whether at some point we should stop."

Only a "[f]ew" scientists who participated in the survey "believe that" the time to stop vaccine research "has come, and most would no doubt say that an HIV vaccine is too important ever to give up on," Connor writes. The "reality is that an HIV vaccine is one of the most difficult scientific problems of our age," he writes. "Scientists need our support and encouragement to redouble their efforts so that one day the scourge of AIDS will be history," he concludes (Connor, Independent, 4/24).