An AIDS vaccine similar to one tied to higher infection rates in a recently failed Merck study may soon be tested in about 3,000 people by the NIH, Bloomberg News reports.

A panel of government advisers voted 23 to 3 late last week in favor of the new study, and Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, says he would review their comments and decide “reasonably soon” whether to proceed.

The the Merck vaccine was terminated last fall when 49 recipients became infected, compared with 33 people who received a placebo. But panel members who backed the government test said it may yield valuable data about vaccines that rely on the action of immune system cells, Bloomberg writes.

The study was reduced in size by about 50 percent after Merck’s test failed, and the International AIDS Vaccine Initiative, a research and advocacy group that has helped bring six vaccines to human testing, said it wouldn’t participate in the government product’s test.

“If this trial goes forward, it will be the most complicated AIDS vaccine trial that any of us will ever have to explain,” said Mitchell Warren, executive director of the AIDS Vaccine Advocacy Coalition, a non-profit advocacy group and a supporter of the trial. “We have a massive undertaking ahead of us.”

One panel member urged caution. “We’re redesigning the aims of human HIV vaccine research without redesigning the vaccine,” said Dennis Burton, an immunologist at Scripps Research Institute in La Jolla, California, who was added to the panel at the meeting. “Let’s not go into a human experiment without a clear idea of what we’re going to learn.”

The failure of Merck’s vaccine, called Ad5 because it contained an adenovirus, or a cold-causing germ, and is composed of genes from HIV combined with the adenovirus. All but one of the infections in the Merck trial struck men, and Merck has said that uncircumcised men and those with high levels of immunity to the adenovirus before getting Ad5 were at highest risk of catching HIV.

For safety reasons, trials of the US vaccine, called VRC after the government’s Vaccine Research Center where it was developed, will include only circumcised men with no immunity to the adenovirus, according to Scott Hammer, a Columbia University infectious disease specialist who heads a group designing the trial.

Juliana McElrath, a panel member from the University of Washington and a lab director for the HIV Vaccine Trials Network, presented a follow-up analysis of some Merck vaccinated subjects who, although infected, had relatively low levels of HIV in their blood. They responded strongly to one component of the Merck vaccine. “In my experience with developing vaccines, if you get a clue in humans, you focus everything on it,” Sadoff said in support of the test at the panel meeting.

However, Martin Delaney, founder of the San Francisco-based AIDS patient advocacy and education group Project Inform, saysthe evidence of potential benefit from Ad5 was too faint, and the risks too great, to go forward. “This is one particular trial that’s going to answer some rather obscure questions that aren’t going to give us an AIDS vaccine any time soon,” he told the panel. “We ought to consider the bigger picture.”