Does the idea of a vaccination for HIV sound far-fetched? You may want to think again.

The world's leading medical researchers in the fight to end HIV/AIDS are "optimistic" about the prospects of clinical trials for three different HIV vaccines, NBC News reports. The trio of separate trials—nicknamed HVTN 702, Imbokodo, and Mosaico—are still ongoing and could very well fail, but scientists are more hopeful than ever about the use of vaccinations to combat the spread of HIV moving forward.

Of the medical trials, HVTN 702 is the oldest and will complete enrollment this summer, with results expected as early as late next year.

Imbokodo and Mosaico are newer and almost identical, with both trials consisting of a regimen of six vaccinations per patient spread out over two doctor's visits. Scientists are exclusively testing Imbokodo on women at a high risk of contracting HIV in southern Africa, while researchers behind Mosaico will reportedly recruit 3,800 gay men and transgender people for trials in the United States, Latin America, and Europe.

Dr. Susan Buchbinder, director of the San Francisco Department of Public Health's Bridge HIV research program and a chair on the Imbokodo and Mosaico trials, told NBC News that the trio of trials marks "one of the most optimistic moments" in the history of HIV/AIDS research.

“We have three vaccines currently being tested in efficacy trials," she told the news site, "and it takes quite a bit to actually be promising enough in the earlier stages stages of trials to move you forward into an efficacy study."

Updates on the ongoing vaccine trials come on the heels of World AIDS Day, which occurs annually on December 1. It's also the latest news to break in a calendar year filled with landmark moments in the global fight to stop the spread of HIV/AIDS: Last month, researchers at American Gene Technologies (AGT), a Maryland-based gene therapy company, claimed to have discovered a potential cure for HIV.

As NewNowNext covered extensively this spring, the world's second- and third-ever HIV-positive patients were "cured" of the virus after undergoing bone marrow transplants for unrelated cancers. While the back-to-back milestones sparked hope and discussion among HIV/AIDS activists, doctors were quick to point out that the transplants were intended as last resort options to treat deadly cancer, not HIV—and that bone marrow transplants are serious procedures with potentially "life-threatening" side effects.

"I’m much more excited about the news that undetectable equals untransmittable," Josh Robbins, an outspoken HIV/AIDS advocate and writer for DatingPositives, told NewNowNext in March.

Talk of HIV "cures" aside, as public health officials noted to NBC News, tools like Pre-exposure prophylaxis (PrEP) and condoms already exist to stop the virus from spreading. It's up to people at a high risk of new infections to use them (and government agencies to make those tools accessible to vulnerable populations).