> The anti-fentanyl antibodies were specific to fentanyl and a fentanyl derivative and did not cross-react with other opioids, such as morphine. That means a vaccinated person would still be able to be treated for pain relief with other opioids

The idea is to remove the fentanyl's effect while keeping the effect of other opioids that are harder to get. The issue with fentanyl isn't the drug use itself, it's the fact that it's too potent for the level of carelessness of your typical dealer/junkie. They can still get high on heroin with a lesser risk of dying.