According to the Post,
scientists are trying to "make sense" of the trial failures and "assess whether they should have seen it coming". 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. Also in September, the company announced that it was halting a similar trial in South Africa. Seven other trials of similar vaccine candidates have been "stopped or put off indefinitely," the Post
reports, adding that some might be "modified" or "canceled outright."
The vaccine candidate could not have caused HIV infection because it contains three HIV proteins and not the entire virus, the Post
reports. According to the Post
, the "working hypothesis for what went wrong" in the Merck trials is that the vaccine candidate "somehow primed the immune system to be more susceptible to HIV infection." However, people for years have been contracting immune-activating infections and receiving vaccines, and there has "never been evidence that those events increased a person's risk of acquiring HIV," the Post
reports, adding that the vaccine trials "would be odd places to first notice such a thing." In addition, participants in the Merck trials who received the vaccine did not have increasingly activated CD4+ T cells compared with people in the placebo group. According to Merck vaccine executive Mark Feinberg, this fact is "kind of an interesting and unexplained observation." Anthony Fauci, director of NIH's National Institute of Allergy and Infectious Diseases, said that "something very, very peculiar" is happening in the trials.
Many researchers and HIV/AIDS advocates are wondering what "effect this near-worst-case scenario" will have on future vaccine trials, according to the Post
. NIH next week is scheduled to meet to examine its HIV vaccine program. The agency's budget for HIV vaccine research is $497 million this fiscal year, the Post
reports. In addition, Merck has spent an undisclosed sum to develop vaccine candidates and manage trials.
Mark Harrington, head of the Treatment Action Group, said the HIV research community "can't afford to have any more trials" like the ones that were halted, adding that researchers "have to stop and reassess and recommit to basic science, or people will begin to lose faith." Ronald Desrosiers, a molecular geneticist at Harvard University, added that NIH has "lost its way in the vaccine arena" and said the agency should redirect HIV funding to basic research.
John Moore -- a virologist at Weill Cornell Medical College who has criticized the vaccine trials -- said he does not "think that what happened" in the Merck trial "is an example of scientists blindly rushing into dangerous things." He added that he does not know "anyone" in the HIV vaccine research community "who said this was going to happen." Although there are no "obvious villains," some experts are "questioning the wisdom" of the trials' strategy because asking "millions of people to take an AIDS vaccine that probably would not protect them from the virus ... would be a hard and confusing task, even in places where the epidemic still rages," according to the Post
Source: Kaiser Family Foundation