there is no need for fentanyl vaccine. Junkies who chase high will just switch to something else and OD themselves.

The psychological dependency on drugs should be treated, but this is much harder problem tightly coupled with larger societal problems. I would love to read research on differences in drug problems in countries with less societal stress and more happiness vs more stress and less happiness.

In the end fentanyl is simply a painkiller, people choose to get high to run away from their life problems. In the mind of patient, the risk of getting OD and becoming drug addict is a better decision, rather than facing grim reality of their daily life and future prospects.