New generation of HIV vaccines may reduce transmission of virus, and traditional prevention strategies needed for foreseeable future
Barcelona - The principal investigator of the U.S. NIAID global HIV trials network said that while there has been important progress on a new generation of T cell-based HIV vaccines that may prove to delay the onset of AIDS symptoms and reduce transmission of the virus, traditional AIDS prevention measures must not be abandoned.
"T cell-based vaccines are approaching the immunogenicity that we feel is needed for effectiveness," said Dr. Lawrence Corey, M.D., the principal investigator of the HIV Vaccine Trials Network, in the plenary address on vaccines at the biannual International AIDS Conference. "They have the potential to significantly impact the epidemic if they are shown to reduce the infectiousness of infected individuals for a prolonged period of time. However, in animal models they do not appear to completely block infection, so traditional prevention strategies are likely to be needed for the foreseeable future."
"We still lack approaches that give the breadth and magnitude of neutralizing antibodies we feel are needed for an effective vaccine that prevents acquisition of HIV worldwide," Corey continued. Scientists believe a combined antibody and T cell response will be needed to most effectively block transmission of the virus.
Corey said the new generation of T cell-based vaccines is likely to enter large-scale clinical trials within two years. He called upon scientists, members of AIDS-affected communities, and policy makers around the world to become more fully engaged in the research process of HIV vaccine development and trials.
"Countries must develop national HIV vaccine plans. Communities must be educated so they can make informed decisions when presented opportunities to participate in clinical trials," he said. "Countries interested in deploying HIV vaccines - especially countries with new epidemics - should seriously consider participating in clinical trials. Otherwise, the potential for these vaccines to slow the epidemic may go unrealized."
Corey stressed that especially because initial vaccines will reduce infectiousness, but not necessarily susceptibility to the virus, their deployment must take place within the context of a larger HIV prevention and treatment effort. "Community participation is critical not only to conduct trials, but to encourage people to continue safe sex and safe injection behaviors," he said.
Corey said it is encouraging that cross-clade T cell responses to HIV are being achieved at high frequency with many of the T cell vaccines currently in clinical trials. "Cross-clade responses to a potent vaccine may provide more efficacy than clade-specific responses to a weak vaccine," he said, “opening the door to economies of scale and global manufacture of a single vaccine.”
"The NIAID HIV Vaccine Trials Network is committed to utilizing its expanding global network to help accelerate the discovery of a safe and effective AIDS vaccine," Corey said. "However, the evaluation of current HIV vaccines requires international coordination among all developers and clinical trial sites unlike any previous vaccine effort."