The ability to induce HIV-specific immune responses does not necessarily mean the vaccine will protect humans from HIV infection. It's one of just five vaccines to ever make it that far in testing, but those that have weren't effective enough to go further.
While there have been HIV vaccines that have been approved for human trials in the past, only one was shown to provide protection against the disease, and it's rate of protection was considered too low to be implemented more widely.
"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", said Barouch.
This study was supported by Janssen Vaccines & Prevention BV and the NIH, the Ragon Institute of MGH, MIT and Harvard, and a cooperative agreement between the Henry M Jackson Foundation for the Advancement of Military Medicine and the US Department of Defense.
But for this "mosaic" vaccine, scientists have developed a treatment made up of pieces of different HIV viruses. While the monkey test is encouraging, there need to be more tests to show that the drug could effectively fend off infections in humans.
The drug protected two-thirds of monkeys in a trial lab, but scientists warn the same result may not occur in humans.
A new study has given the researchers a ray of light in the battle to safeguard people from the most widespread virus, HIV-1. Currently, around 37 million people are living with HIV/Aids across the world: levels that amount to a pandemic.
But despite advances in treatment for HIV, a cure or vaccine against the virus has never been found.
Inventing a vaccine has proved an enormous challenge for scientists, in part because there are so many strains of the virus, but also because HIV is adept at mutating to elude attack from our immune systems.
The researchers also noted several limitations, including the fact that that the relevance of vaccine protection in rhesus monkeys to clinical efficacy in humans remains unclear. All of the vaccine combinations turned out safe and produced an anti-HIV immunity. The human trial, which involved 393 participants, produced an anti-HIV immune system response. The adults came from clinics across East Africa, South Africa, the USA and Thailand.
"These results represent an important milestone", Barouch said when speaking with BBC News.
The same vaccine was also tested on rhesus monkeys and proved to be partially effective, protecting 67 percent of the test subjects from simian-human immunodeficiency virus, a virus similar to HIV.
Buchbinder said that she hoped "to validate our non-human primate model to see if it works for humans and if we see the same correlates of protection".