A volunteer made AIDS symbols with red ribbons during a vaccination program organized by nongovernment organization on the outskirts of the northeastern Indian city of Siliguri Aug. 5, 2008. An estimated 39 million people worldwide have died from AIDS-related diseases since the virus was discovered 32 years ago. Reuters

In the race to end HIV/AIDS around the world, nothing says victory like headlines trumpeting progress toward a state-of-the-art preventative drug. A new treatment compound said to block HIV infection has raised new hopes of eviscerating the virus before it can take hold in the body. However, researchers caution that their work is far from over. The new treatment that functions by prompting muscle cells to release proteins that mimic the body’s natural defense mechanisms has shown promise in trials involving monkeys but would still have to prove itself in humans, and there’s no telling how long such trials could take or whether the results could be duplicated.

"We are closer than any other approach to universal protection, but we still have hurdles, primarily with safety for giving it to many, many people,” the study’s lead author Michael Farzan, an infectious disease specialist of the Scripps Research Institute in Florida, told the BBC. Human trials would take place in three stages, the first involving human test subjects being injected with the antibody-simulating protein. The final stage would include giving the new compound to people considered at higher risk of contracting HIV, such as men who have unprotected sex with other men.

Developing a vaccine against HIV is often seen as the holy grail of AIDS research. In the same way that vaccines have ended such dangerous global killers as smallpox and tuberculosis, developing an injection to prevent HIV infection could make ending the worldwide epidemic that kills an estimated 1.5 million people every year a reality.

The new treatment study, published Wednesday in the journal Nature, took a different approach to HIV vaccine development than has previously been attempted. Unlike other existing vaccines, which typically work by killing or weakening the entire virus, the latest treatment stimulates the body into producing a protein that binds to and blocks the HIV virus from latching onto cells. In monkeys, the drug blocked every strain of HIV-1,HIV-2 and simian immunodeficiency virus, or SIV. “It appears to be as good as, if not better than, anything else that’s being tried,” Philip R. Johnson, director of the Children’s Hospital of Philadelphia Research Institute, told the New York Times.

Health experts have been down that road plenty of times before with often disappointing results. In 2013, a major study involving testing of an encouraging HIV vaccine was abruptly scrapped after researchers found no evidence that the drug would prevent HIV. "It was a big traumatic event to put all this effort in and then have the vaccine trial stop,” the study’s lead researcher Scott Hammer of the Columbia University College of Physicians and Surgeons told NPR that year. The trial involved 2,500 participants, spanned 19 cities and came with a $77 million price tag.

Earlier, in 2003, researchers at the forefront of the HIV vaccine movement admitted they’d hit a wall. That year, the first-ever HIV trial to reach stage three, a major milestone by many accounts, ended in failure, according to AIDS Map. That kind of trial and error is simply part of the process of searching for the right vaccine.

The first flicker of hope for creating an effective HIV vaccine came in 2009 following a study in Thailand that showed a modest reduction in HIV infection rates among 16,000 test subjects. The 31 percent drop in infections wasn’t enough to signify a total breakthrough, but it did pave the way for further investigation.

The reasons an HIV vaccine has evaded scientists for so long are many. For one, vaccines must go through several stages of rigorous testing before they can be given to healthy, non-infected people. Scientists labored for over nine decades to develop a vaccine against pertussis, or whooping cough. Nearly 50 years passed between the discovery of polio and the release of a vaccine, and more than a century went by after typhoid was identified. The HIV virus was detected a little more than 30 years ago. To date, only one person in the entire world has been labeled “cured” of HIV.

In many ways, HIV drugs have come a long way and brought the world much closer to ending the HIV epidemic. Antiretroviral drugs aimed at purging the virus from the human body have become more effective than ever and can significantly decrease viral loads to negligible levels. However, stopping treatment often results in the virus rebounding. Pre-exposure prophylaxis, or PrEP, treatments – using antiretroviral drugs preemptively before infection has even occurred – have momentum in some parts of the world as a capable defense against the spread of HIV.

With infection rates globally having stabilized in recent years, AIDS-related deaths are on the decline, and more people than ever are on life-saving treatments. "It’s a really promising time in HIV research," said David Gerberry, assistant professor of mathematics at Xavier University who has modeled HIV interventions in sub-Saharan Africa. At the same time, "there’s a big disconnect between something that works biologically and something that works socially and in real practice."