Nov 02, 2007  |  By: DYANA BAGBY  | COMMENTS     

ATLANTA — Some U.S. participants in the recently halted HIV vaccine trial co-sponsored by Merck & Co. are being told by study coordinators they may be at higher risk for contracting HIV if they received the actual vaccine and not the placebo.

Globally, some 3,000 volunteers participated in the HIV vaccine trial, including dozens of gay men in Atlanta who joined the study through Emory University’s Hope Clinic. All volunteers were HIV negative when they began participation.

“We are talking to each and every participant and asking them to assume the worst and act as if they’ve been put at greater risk and to be extra vigilant in being safe,” said Sarah Alexander, spokesperson for the HIV Vaccine Trials Network.

Dr. Mark Mulligan, executive director of the Hope Clinic, said participants have been contacted about possible risks, but noted that the vaccine itself could not give anyone HIV.

“The vaccine itself cannot cause HIV — we must stress that,” he said.

So far,volunteers in the trial appear to be taking the warnings in stride.

“This doesn’t really bother me,” said Randy Reardon, 42, a gay man who volunteered for what is known as the STEP trial two years ago.

“But it may make some people more hesitant [to participate in future HIV vaccine trials] because they may not get all the correct information,” added Reardon, who is studying to be a nurse practitioner at Georgia State University. “Whether it’s the vaccine or behavior, I don’t know. But I’m not worried because my behavior hasn’t changed.”

The first detailed review of the STEP data will occur on Nov. 7 at a special open scientific session of the HIV Vaccine Trial Network in Seattle.

Merck officials did not respond to interview requests by press time.

Phase II of the STEP trial in the U.S., Australia, South America and the Caribbean was halted Sept. 21 after three years of research when it was determined by an independent Data & Safety Monitoring Board that the vaccine did not stave off HIV infection nor reduce the virus in those who became infected.

In an Oct. 23 press release, the National Institute of Allergy & Infectious stated a “sister” trial in South Africa, known as the Phambili study and using the same HIV vaccine, also halted enrollment and immunizations. The institute is part of the National Institutes of Health, which funded the Merck investigational vaccine trial. The South African trial, also in Phase II and begun in February, was stopped because an independent DSMB there also determined the vaccine was not working.

The DSMB in South Africa also recommended volunteers be told whether they received the vaccine or placebo, be strongly encouraged to return to their study sites for protocol-related tests, and be counseled about the possibility “that those who received the vaccine may have an increased susceptibility to acquiring HIV infections,” according to an NIH press release.

A difference in the STEP trial and the Phambili trial, while both used the same HIV vaccine, is that the volunteers for the STEP trial were overwhelmingly gay men while in South Africa most volunteers were heterosexual women.

When vaccinations were stopped in the STEP study in the U.S. and other countries last month, the study leadership for Phambili temporarily halted enrollment and injections there as well, said Alexander, the HIV Vaccine Trials Network spokesperson.

The Phambili DSMB then reviewed the available data from the STEP study, which showed 24 cases of HIV infection among the 741 volunteers who received at least one dose of the investigational vaccine, while 21 cases of HIV infection were seen in the 762 participants who received at least one dose of the placebo.

According to the NIAID, in the subgroup of STEP trial participants who had received at least two vaccinations and who were HIV-negative for at least the first 12 weeks of the trial, the DSMB found 19 cases of HIV infection among the 672 volunteers who received the investigational vaccine and 11 cases of HIV infection among the 691 participants who received the placebo.

At the Phambili DSMB meeting last month, members made the decision to change the temporary halt into a permanent one based on these numbers, Alexander said.

“There have not been any injections in any participants in either of the studies since the announcement Sept. 21,” Alexander explained.

While the STEP study numbers are not statistically significant, ...