An experimental AIDS vaccine that's worked better than anything else tried so far is going to be tested in South Africa, U.S. health officials said Wednesday.
They've tweaked the vaccine, which prevented infection by just about a third, and hope it will work better in this trial.
"For the first time in seven years, the scientific community is embarking on a large-scale clinical trial of an HIV vaccine, the product of years of study and experimentation," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID).
NIAID is part of the National Institutes of Health and a co-funder of the trial.
"A safe and effective HIV vaccine could help bring about a durable end to the HIV/AIDS pandemic and is particularly needed in southern Africa, where HIV is more pervasive than anywhere else in the world."
There's no cure for the human immunodeficiency virus (HIV) that causes AIDS, but cocktails of antiviral drugs can keep it under control — and if people take some of the same drugs they can protect themselves against infection.
That approach, called pre-exposure prophylaxis or PrEP can reduce the risk of catching HIV by 90 percent if people use it consistently. But it's not cheap, and studies suggest it could be difficult for people in developing countries to stick to, if they could even get the drugs.
Most experts agree the best way to fight the virus — which infects 35 million people globally and which kills 1.2 million a year — would be to have a good vaccine.
"While we are making encouraging progress — new HIV infections have fallen by 35 percent globally since 2000 — the development of a safe and effective HIV vaccine would be the ultimate game-changer," Fauci wrote in a blog post.
The experimental vaccine being tested in based on a U.S. military vaccine called RV144 that protected 31 percent of volunteers in Thailand in 2009.
"The design and schedule of the RV144 vaccine regimen have been adjusted to try to increase the magnitude and duration of vaccine-elicited immune responses," NIAID said. "The trial is slated to begin in November 2016, pending regulatory approval."
NIAID hopes to enroll 5,400 people who are not infected with HIV.
"Vaccine research also continues in the laboratory, where scientists are investigating the use of potent antibodies that block a high percentage of global HIV strains from infecting human cells," Fauci wrote.
"These so-called broadly neutralizing antibodies (bNAbs) can occur naturally; however, they occur in high titers in a relatively small proportion of infected individuals and they usually develop only after two or more years of infection, too late to be of significant benefit to the patient. However, if a vaccine could stimulate uninfected people's immune systems to make bNAbs, the antibodies might protect those people from HIV infection."