Scientists will have to take "enormous intellectual leaps" to develop an AIDS vaccine in the coming years, say researchers clearly frustrated by the failure of a once-promising shot.

The researchers, including a top National Institutes of Health official, want new people with new ideas to step up and join the search. They say the focus of their research should be on discovering a vaccine rather than on clinical trials for evaluating medicines that may or may not work.

"Design of a vaccine that blocks HIV infection will require enormous intellectual leaps beyond present day knowledge," concluded a broad team of researchers writing in Friday's edition of the journal Science.

More than 6,500 new HIV infections occur daily worldwide. A recent high-profile trial of a potential vaccine not only failed to prevent infection, but those who got the inoculation appeared at increased risk of infection compared with those who were given a placebo.

After the disappointing results, the National Institute of Allergy and Infectious Diseases held a summit in March on how to reinvigorate vaccine research.

The institute will still support studies in people — but it is raising the bar that candidate vaccines need to pass to get federal support. NIH is looking for fresh ideas on how to approach HIV vaccine discovery, and emphasizing basic laboratory research to fill in key gaps in knowledge. Among the priorities will be increased research in chimpanzees, the Science article says.

The recent failed vaccine study showed "we were maybe on the wrong track a bit," Dr. Anthony Fauci, the institute's director, told a Science podcast. "We will be turning the knob, as I like to say, more preferentially toward answering some of the fundamental questions that have gone unanswered," he said.

When contractors don't meet milestones, or when initiatives don't attract the highest quality of applications, money will be redirected to more promising research activities, Fauci's team wrote. Unfortunately, the need for more resources aimed at discovering a vaccine comes at a time when the National Institutes of Health's budget remains flat, the officials said.

"Should growth in the NIH budget be reinstated in future years, one of the highest priorities will be to target those additional resources to HIV vaccine programs, particularly vaccine discovery research," the health officials wrote.