A series of HIV-prevention vaccine regimens have been evaluated in a study of uninfected human volunteers in five countries, and the results appear promising.
The study, published in The Lancet, was conducted by a team of researchers led by Beth Israel Deaconess Medical Center's Dr. Dan H. Barouch, director of the Center for Virology and Vaccine Research in collaboration with Janssen Vaccines & Prevention and other partners.
Barouch and his colleagues tested the same vaccine for its ability to protect rhesus monkeys challenged with an HIV-like virus from infection. The vaccines induced robust and comparable immune responses in humans and monkeys and protected monkeys against the acquisition of infection.
"This study demonstrates that the mosaic Ad26/Ad26 plus gp140 vaccine candidate induced robust and comparable immune responses in human and monkeys," said Barouch, who also is a professor of medicine at Harvard Medical School. "Moreover, the vaccine provided 67% protection against viral challenge in monkeys."
Intended to provide broad protection from the many strains of HIV that are prevalent worldwide, the "mosaic" vaccine contains a patchwork of genetic sequences found among various HIV strains. Known as APPROACH, the phase 1/2a trial tested seven different Ad26/Env HIV vaccine regimens for their safety, tolerability and the ability to elicit immune responses in 393 healthy adult volunteers in Rwanda, South Africa, Thailand, Uganda and the United States. All vaccine regimens were well-tolerated and induced robust immune responses in the participants.
"Based on these data, the mosaic Ad26/Env HIV-1 vaccine has been advanced into a phase 2b clinical efficacy study to determine whether this vaccine will prevent HIV infection in humans in southern Africa," Barouch said. "We expect results in 2021. This is only the 5th HIV vaccine concept that will be tested for efficacy in humans in the 35-plus year history of the global HIV epidemic."