Earlier tests on small groups of people have demonstrated the vaccine's safety. Now, the Phase III trial is being conducted to show whether it is effective. Brown doctors are part of the national team participating in this phase.
Brown doctors are part of a team of physicians across the country hoping to answer the question of whether AIDS can be prevented by a particular vaccine.
It is the largest anti-HIV vaccine trial to date, said Dr. Kenneth Mayer, professor of medicine and community health at the School of Medicine and chief of the Infectious Disease Division of Memorial Hospital of Rhode Island in Pawtucket.
"What's exciting about it is there have been enough preliminary trials so that we can say it's safe," Mayer says. Earlier tests on small groups of people have demonstrated the vaccine's safety. Now, the Phase III trial is being conducted to show whether it is effective.
The 5,000 volunteers in the United States can't become infected from the vaccine, called AIDSVAX.
About 50 of the volunteers will be from Rhode Island, recruited by Project ACHIEVE, a collaboration among Memorial Hospital, Miriam Hospital and Boston's Fenway Community Health Center for gay men. The project also includes Dr. Michelle Lally, assistant professor of medicine at Brown and principal investigator at Miriam Hospital, and Dr. Alvan Fisher, associate director of Brown's AIDS Program, which is headed by Mayer.
A similar study is being conducted on 2,500 people in Thailand.
The vaccine is controversial, Mayer says, because scientists disagree on the best way to prevent AIDS. Some critics of AIDSVAX say a better way to prevent AIDS would be to create a vaccine that would prime the body's cells to kill infected foreign cells. Instead, the AIDSVAX causes the immune system to make antibodies to fight free virus. The hepatitis B vaccine works this way.
The National Institutes of Health believe the antibody approach would not provide immunity. The NIH decided not to fund the testing but is allowing it to continue, Mayer says. Instead, the funding is coming from VaxGen Inc., a Brisbane, Calif., company that developed the vaccine.
The vaccine trial is also controversial from an ethical standpoint because it seeks volunteers at high risk for infection, including homosexual men, intravenous drug users, sex partners of an infected person, or women with multiple partners.
To resolve the ethical challenge, the volunteers are counseled on how to avoid AIDS. But during an earlier vaccine test on a small group of high-risk people, Mayer says, the testers wondered whether people who accepted a vaccine would increase risk-taking behavior. The study showed most didn't.
Investigators will know by fall 2001 whether AIDSVAX is effective, Mayer says.
If the vaccine does not work, scientists would learn that the antibody approach is not worth pursuing and could channel research elsewhere, Mayer says.
The results could show that the vaccine works part of the time, or only for some people. That would be valuable for people such as commercial sex workers who may not be able to protect themselves, Mayer says.
"If we have a vaccine protecting people 50 percent of the time," Mayer says, "even something that's 50 percent effective can have an enormous public health impact."