The synthetic opioid is a leading cause of overdose deaths in the United States. The experimental vaccine trains the body to make antibodies that bind fentanyl in the bloodstream, thereby blocking its euphoric and lethal effects.


Fentanyl is 50 times stronger than heroin and 100 times stronger than morphine. Laboratory tests in rats showed that up to 98% of fentanyl was blocked from entering the brain. Researchers are also exploring an oral vaccine formulation for future trials, and some scientists note that such vaccines won’t solve addiction but could become a new tool in overdose prevention.