Volunteers in a failed worldwide AIDS-vaccine study headed by Seattle researchers will be told whether they were given the experimental...

Volunteers in a failed worldwide AIDS-vaccine study headed by Seattle researchers will be told whether they were given the experimental vaccine — and may face a higher risk of getting HIV than those who got a placebo.

“In our deliberations about this, the central point was: ‘What’s best for the participant?’ ” said Dr. Ann Duerr, an associate director of the HIV Vaccine Trials Network, based at Fred Hutchinson Cancer Research Center, and one of the sponsors of the so-called “STEP vaccine” study.

The study was halted in September because the vaccine wasn’t working; last week the researchers announced that a deeper analysis showed that certain volunteers who got the vaccine were more likely to contract HIV, though they are not yet sure why.

About 100 volunteers were from Seattle. Other sites include 15 other U.S. cities, as well as some in Canada, Peru, Brazil, Australia, Jamaica, Haiti, Puerto Rico and the Dominican Republic.

Save 75% on a Digital Subscription Today

In total, 3,000 volunteers — men and women between ages 18 and 45 considered to be at high risk of HIV infection — will now be encouraged to return to their study sites for “risk-reduction” counseling and study-related tests, said the study’s sponsors.

Skewed data?

The vaccine, being developed by Merck pharmaceutical company, used a disabled form of a common cold virus to deliver three synthetic HIV genes into the body in hope of stimulating an HIV-targeted immune response.

The decision to “unblind” the study also focused on whether it would be more beneficial for follow-up research to maintain the study’s “double-blind” design, in which neither researchers nor volunteers know who got the real vaccine.

And that decision was neither simple nor easy, said Duerr, who is also a professor at the University of Washington.

“There was a huge spectrum of opinions,” she said. “This issue isn’t really black and white.”

The fear is that volunteers, if they know whether they got the medication being studied or a placebo, might change their behavior enough that information collected afterward would be tainted.

“Unblinding the patient has the potential to bias the data in the future,” noted Garnet Anderson, an assistant professor of biostatistics at the University of Washington. Anderson was a co-investigator of a huge study of hormone-replacement therapy in women that was halted in 2002 when it found the hormones had adverse effects. The research was later unblinded.

In the end, researchers realized that “this isn’t the last trial we’ll do,” Duerr said, and that keeping the trust of potential volunteers was paramount.

“It’s very important that we keep faith with the community,” she said.

Mitchell Warren, executive director of the New York-based AIDS Vaccine Advocacy Coalition, applauded the decision. Not only will it increase the chances of getting volunteers for future studies, he said, but it may actually help with future data collection from the trial’s participants because it signals that the researchers are putting their safety first.

“In many ways unblinding may be a great motivator to keep people coming back,” he said.

Carol M. Ostrom: 206-464-2249 or costrom@seattletimes.com