Leaders of Merck's Canceled HIV Vaccine Study Notify Participants Whether They Received Vaccine, Placebo

Leaders of Merck's experimental HIV vaccine study on Monday decided to notify all of the trial's 3,000 participants whether they were given the vaccine or a placebo, the San Francisco Chronicle reports. Representatives of Merck, NIH and a group of physicians who enrolled the trial participants decided to unblind the study after several days of discussions at an HIV Vaccine Trials Network conference last week in Seattle (Russell, San Francisco Chronicle, 11/14).

Merck in September announced that it had ended the Phase II trial, which began in late 2004 and involved HIV-negative volunteers, after the experimental vaccine failed to prevent HIV infection in participants or prove effective in delaying the progression of the virus to AIDS. The trial was stopped by the Data and Safety Monitoring Board, an independent overseer. Data recently suggested that the vaccine was ineffective among some trial participants with a pre-existing immunity to a common cold virus and that the vaccine might have increased their susceptibility to HIV infection.

Researchers late last month asked trial participants to return to study sites for tests and additional follow-up regarding a possible increased risk of HIV. Researchers in South Africa who were testing the same vaccine have told the 801 participants in the separate trial if they received the vaccine (Kaiser Daily HIV/AIDS Report, 11/12).

According to the Chronicle, there was a "compelling ethical case" to unblind the study in light of the new data; however, unblinding could "limi[t] the scientific value" of any data gathered, as researchers continue to observe the participants. There was "lots of opportunity for discussion among the investigators and the community, and the vast majority were in favor of un-blinding" the study, Susan Buchbinder -- director of HIV Research for the San Francisco Department of Public Health and co-chair of the committee that established the protocols for the trial -- said (San Francisco Chronicle, 11/14).

"In our deliberations about this, the central point was: 'What's best for the participant?'" Ann Duerr, an associate director of the HIV Vaccine Trials Network at the Fred Hutchinson Cancer Research Center and one of the sponsors of the study -- said. Researchers ultimately realized that "this isn't the last trial we'll do," Duerr said, adding that it is "very important that we keep faith with the community."

Mitchell Warren, executive director of the AIDS Vaccine Advocacy Coalition, welcomed the decision, saying, "In many ways unblinding may be a great motivator to keep people coming back," he said (Ostrom, Seattle Times, 11/14).

NPR's "News & Notes" on Tuesday included a discussion with NPR science correspondent Brenda Wilson about the vaccine (Chideya [1], "News & Notes," NPR, 11/13). Audio of the segment is available online. Tuesday's program also included a discussion with Buchbinder about the trial (Chideya [2], "News & Notes," NPR, 11/13). Audio of the segment is available online.

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