They’ve developed a vaccine that could block the opioid high altogether, and eradicate the patient’s desire to seek it. The research was published yesterday in the journal Angewandte Chemie. In the study, the researchers worked with the drug fentanyl, an opioid sold in strong doses on the street and responsible for an uptick in overdoses. The researchers slightly modified the contents of a fentanyl molecule while keeping its structure intact so that the immune system would recognize it. Over the course of six weeks, mice were injected with these molecules three times, like vaccine booster shots to train the immune system. At the end of that period, the researchers found that it was impossible to get the mice high, no matter how much fentanyl the mice were given. When the researchers sampled some of the mice’s blood and combined it with fentanyl molecules in a petri dish, the antibodies killed the drug molecules, leading the researchers to believe that they would stop the drug in the bloodstream and before they could reach the brain. A month later, most of the vaccinated mice survived a lethal dose of the drug. Since the immune system is so precise, the fentanyl vaccine wouldn’t eliminate the high for other opioids like heroin or oxycodone. That’s a good thing if a patient needs painkillers for medical purposes, but it also means that an addict could still get high if fentanyl is mixed with another opioid, as it often is when bought illegally. In future studies the researchers hope to test a mixed vaccine for fentanyl and heroin. While these findings show that the fentanyl vaccine is promising, it’s not quite ready to be used in humans. But they might have come just at the right time, as President Obama just asked Congress for more than $1 billion to combat the opioid epidemic. An influx of new funding might mean that more scientists will work together to quickly develop a vaccine for opioids.