Scientists had argued whether it was justified to go ahead with a large trial of a vaccine that could not be expected to protect people against infection in the hope of finding something in their biological responses that could help design a better vaccine down the road.
AIDS has killed 25 million people since it was first identified in the 1980s and it infects 33 million people globally. There is no cure although a cocktail of drugs can keep the infection suppressed.
"An HIV vaccine continues to be our best hope for ending the HIV pandemic," the NIAID said.
"DIFFICULT PERIOD"
Fauci said he decided it would be better to do smaller, more focused tests and if and when one of those gets a result, to follow that lead.
"We are in an interesting and, some would say, difficult period," Fauci said. "The obvious empirical approaches have not worked."
But while about 30 vaccines are being tested, none has come even close to preventing infection in people.
"Because the PAVE vaccine candidate is different from the STEP candidate, we can still learn something from testing the PAVE candidate in humans. It's just not necessary to do so in a trial involving thousands, as called for in the PAVE 100 design," International AIDS Vaccine Initiative president Seth Berkley said in a statement.
"The decision by NIAID does not reflect paralysis in the AIDS vaccine field, or a lack of direction forward. In fact, it reflects the opposite. It reflects the dynamic learning that is the scientific process, that is pharmaceutical product development," Berkley added.
