First-of-its-kind fentanyl vaccine targets overdoses before they start

A vaccine to protect against fentanyl's deadly effects is headed for clinical trials in humans.

The vaccine, which showed positive results in studies of mice and rats, is designed to block fentanyl from entering the brain, blocking its effects and preventing overdoses.

"In a vaccinated individual, those anti-fentanyl antibodies are in the blood," Haile told Fox News Digital. "So if they consume fentanyl, the antibodies grab onto the drug and prevent it from getting into the brain. They would feel no effects if they ingest fentanyl - absolutely none. And they would not overdose."

Eventually, he said, the fentanyl would be eliminated from the body.

In the mice and rat studies, the animals still had antibodies against fentanyl six months after vaccination, added Haile, who is also a research associate professor of psychology at UH and a founding member of the UH Drug Discovery Institute.

The main benefit, according to Haile, is that the vaccine would reduce the potential health dangers of fentanyl.

Following successful testing in mice and rats, the first human clinical trial is slated to begin in early 2026 at the Center for Human Drug Research, which is associated with the University of Leiden in the Netherlands.

After the phase 1 trial for safety, a phase 2 trial will test whether the vaccine effectively blocks fentanyl's effects in humans.

The primary limitation is that data is so far only available for mouse models, and it's unknown how effective the vaccine would be in humans.

"Also, unlike other vaccines, we use extremely low doses of the components," he noted. "We have put the vaccine into a lot of animals and have not seen any adverse side effects at all."

Even in a toxicology study, during which the researchers administered 20 times the dose of the vaccine that would be given to humans, they still saw no overt signs of toxicity, according to Haile.

Military and national security personnel could also benefit from the vaccine, Haile said, as it could help protect against fentanyl and fentanyl-like compounds that have been used as chemical threats.

Looking ahead, Haile said this could pave the way for the approval of other anti-drug vaccines, such as cocaine and methamphetamine, which are already in the works.

"If we can tackle the primary ones - fentanyl, cocaine and methamphetamine - we will be saving hundreds of thousands of lives," he added.

Dr. Marc Siegel, senior medical analyst for Fox News, said the progress of the vaccine is a "very exciting advance with a huge upside."

The antidote for fentanyl (Narcan) is limited because fentanyl lasts for many hours, but the Narcan (an opioid antagonist) wears off after only a few hours and has to be readministered, Siegel pointed out.

The vaccine was developed with funding from the U.S. Department of Defense and licensed to biotech startup ARMR Sciences.